Deep Sky Astrophotography (Gear Discussion)

[jrista]

Re: Deep Sky Astrophotography

So, I FINALLY got some clear sky for a period of several hours, and was finally able to create a nicer image of Horse Head and Flame Nebulas:


See at my blog

Integration of 1h 30m of subs. Not really enough to reduce noise to an acceptable level, I need about 5h total to really reduce noise. But I was able to stretch and enhance the nebula detail quite a bit!

Stack of 30x180s @ ISO 400. Canon 7D, EF 600mm f/4 L II as telescope. Calibrated with 30 flats and 100 bias.

See full size image at AstroBin:

Nice work. So there's no tracking device, correct? This is the full size image? So it's a crop of the image?

Oh yes! There is tracking. Very accurate tracking, actually. I used an Orion Atlas EQ-G equatorial tracking mount, along with the ADM D-type side-by-side tandem saddle, in which my 600/4 II lens was mounted with a custom dovetail plate, and the Orion SSAG (StarShoot Auto Guider) was mounted next to it. The SSAG does autoguiding...it finds a star, then sends special instructions to the mount to keep that star in the exact same place at all times.

There is a total of 1 hour and 30 minutes exposure time here (it's called integration time, as it is not a single exposure, it's a calibrated stack of images). That was achieved by stacking 30x 180 second individual exposures, each of which were calibrated with a master flat frame (to reduce vignetting) and a master bias frame (to eliminate fixed sensor noise). There is no way you could do that without tracking. Tracking, and guiding, is essential to keep the shutter open that long without stars trailing (at 600mm, stars trail by 1/3rd of a second exposure without tracking). Tonight, I was able to get my mount aligned and guided well enough to get 0.08 RMS R.A. axis tracking precision, and 0.10 RMS Dec. axis tracking. I had minimal guiding corrections, once every several seconds at the most frequent, which is really very good. When guiding is worse than that, stars end up getting larger, sometimes misshapen. The stars in this shot are pretty round.

The only real problem is the field isn't entirely flat. I tried to flatten it, but that ended up making the corners bright, so I need to figure out how to fix that.

Regarding crop, it isn't quite the same as with standard photography. Since this is a stack of multiple frames, the total image size after stacking is usually larger than a single frame. The image near the edges is usually pretty ugly with stacking artifacts, so you usually crop inwards to get rid of that junk. After cropping, this image was still actually slightly larger than a standard 7D frame (5184x3456). I downsampled that by 50% when uploading to AstroBin, so the full size image you see there roughly represents the full 7D frame, even though it's 1/4 the size now.

 

[philmoz]

Re: Deep Sky Astrophotography

So, I FINALLY got some clear sky for a period of several hours, and was finally able to create a nicer image of Horse Head and Flame Nebulas:


See at my blog

Integration of 1h 30m of subs. Not really enough to reduce noise to an acceptable level, I need about 5h total to really reduce noise. But I was able to stretch and enhance the nebula detail quite a bit!

Stack of 30x180s @ ISO 400. Canon 7D, EF 600mm f/4 L II as telescope. Calibrated with 30 flats and 100 bias.

See full size image at AstroBin:

Awesome 8)

(I can feel a bout of GAS in my future.)

Phil.

 

[CarlTN]

Re: Deep Sky Astrophotography

So, I FINALLY got some clear sky for a period of several hours, and was finally able to create a nicer image of Horse Head and Flame Nebulas:


See at my blog

Integration of 1h 30m of subs. Not really enough to reduce noise to an acceptable level, I need about 5h total to really reduce noise. But I was able to stretch and enhance the nebula detail quite a bit!

Stack of 30x180s @ ISO 400. Canon 7D, EF 600mm f/4 L II as telescope. Calibrated with 30 flats and 100 bias.

See full size image at AstroBin:

Nice work. So there's no tracking device, correct? This is the full size image? So it's a crop of the image?

Oh yes! There is tracking. Very accurate tracking, actually. I used an Orion Atlas EQ-G equatorial tracking mount, along with the ADM D-type side-by-side tandem saddle, in which my 600/4 II lens was mounted with a custom dovetail plate, and the Orion SSAG (StarShoot Auto Guider) was mounted next to it. The SSAG does autoguiding...it finds a star, then sends special instructions to the mount to keep that star in the exact same place at all times.

There is a total of 1 hour and 30 minutes exposure time here (it's called integration time, as it is not a single exposure, it's a calibrated stack of images). That was achieved by stacking 30x 180 second individual exposures, each of which were calibrated with a master flat frame (to reduce vignetting) and a master bias frame (to eliminate fixed sensor noise). There is no way you could do that without tracking. Tracking, and guiding, is essential to keep the shutter open that long without stars trailing (at 600mm, stars trail by 1/3rd of a second exposure without tracking). Tonight, I was able to get my mount aligned and guided well enough to get 0.08 RMS R.A. axis tracking precision, and 0.10 RMS Dec. axis tracking. I had minimal guiding corrections, once every several seconds at the most frequent, which is really very good. When guiding is worse than that, stars end up getting larger, sometimes misshapen. The stars in this shot are pretty round.

The only real problem is the field isn't entirely flat. I tried to flatten it, but that ended up making the corners bright, so I need to figure out how to fix that.

Regarding crop, it isn't quite the same as with standard photography. Since this is a stack of multiple frames, the total image size after stacking is usually larger than a single frame. The image near the edges is usually pretty ugly with stacking artifacts, so you usually crop inwards to get rid of that junk. After cropping, this image was still actually slightly larger than a standard 7D frame (5184x3456). I downsampled that by 50% when uploading to AstroBin, so the full size image you see there roughly represents the full 7D frame, even though it's 1/4 the size now.

That's quite interesting, and again, well done! A co-worker of my brother's, is trying a similar stacking technique, but he has no tracking device, and the image I saw was even smaller in pixel dimensions than this one. He's too stuck up to even talk to me about it, haha...

In any case, keep up the good work! I hate to feed your maniacal ego though, but as I told you before, I do love astro images! It's great you are so committed to it. How do the cold temps affect your 600 lens? Does it frost any? I assume you use the hood? I guess you allow for the time to cool it down, as well as let it warm up gradually when you bring it in (maybe in an unheated garage or similar)?

Btw I tried to see the ISS tonight, and never saw it. Kind of sucks because the sky was extremely clear, I had my Vanguard 8.5 x 45mm ED bino's out and all ready. I've seen it before, so it was odd I couldn't this time. I only saw about 15 high flying jet airliners and one turboprop that must have been at around 20,000 feet...and I could see it approaching from only 20 degrees above the horizon, so it was pretty far away at first. These bino's aren't quite Swarovski, they have loads more CA and astigmatism, but their "macro" contrast is actually superior...at least to the previous generation "Swarovision" that I compared them directly to for about 45 minutes...likely not the current generation though. But that's ok, I'd rather spend funds towards camera gear!

 

[jprusa]

Re: Deep Sky Astrophotography

So, I FINALLY got some clear sky for a period of several hours, and was finally able to create a nicer image of Horse Head and Flame Nebulas:


See at my blog

Integration of 1h 30m of subs. Not really enough to reduce noise to an acceptable level, I need about 5h total to really reduce noise. But I was able to stretch and enhance the nebula detail quite a bit!

Stack of 30x180s @ ISO 400. Canon 7D, EF 600mm f/4 L II as telescope. Calibrated with 30 flats and 100 bias.

See full size image at AstroBin:

Very nice Jon.

 

[jrista]

Re: Deep Sky Astrophotography

... I hate to feed your maniacal ego though...

You know, you've been taking little jabs at me like that for days. I'm not really sure what set you off, but so long as you continue to slip little insults into your responses, I really have no reason to spend time responding to your questions. This isn't a thin-skin thing, either. It's simply a matter of principal. If you have a bone to pick with me, pick it, in PMs. Otherwise, just be cordial out in the public forums...that really isn't asking much.

 

[scyrene]

Re: Deep Sky Astrophotography

I hope it's not inappropriate, but my last astro effort (and my only one recently) was the following. California Nebula, suburban/semi-rural site, UHC filter. I've been repeatedly astounded how bright this is in ultra widefield (~14mm) shots, so I decided to go closer. But no flats, which seem to disagree with this lens (pity), and no darks cos I forgot. Still...

Nice shot. It looks a little overprocessed...saturation is a bit harsh, and the stars have that funky halo around them. I'd pull back on the processing a bit, reduce saturation...and that would actually probably help bring out more subtlety in nebula detail.

Out of curiosity, how long was the exposure?

Ah, the haloes are due to using a very wide aperture with the UHC filter, which they're not meant for. I get big red haloes round the medium-brightness stars, so I use 'remove colour fringing' in Lightroom, but that does leave these grey haloes, which isn't what I'd prefer, but it's a limitation of my setup at present. I'd like to stop down to reduce this, but I can't afford the light loss, as my tracking won't go beyond 1-2m mins per subframe. Also using this lens wide open creates all sorts of weird colour casts across the image, so it needs a bit more processing than the 100L Macro, for instance. The upshot is you get a lot more faint stars.

I rather like the saturation, though I can understand why some would tone it down. It's always a tough balance. This is 113x1min exposures at f/1.2 (50D @ ISO 1600)

You should look into getting Astronomy Tools. It's a set of PS actions that might help you with your halo problems. It's pretty cheap, around $20.

I don't have Photoshop, I use Gimp. It's a lot of work, but the opportunities to shoot the night sky are so rare, it's not so bad - I can set aside a day or two every couple of months. Thanks though. I've found a better tracker, so I might well be able to use narrower apertures. Also, Astronomik have released full frame in-camera filters, so that should help too.

 

[jrista]

Re: Deep Sky Astrophotography

I hope it's not inappropriate, but my last astro effort (and my only one recently) was the following. California Nebula, suburban/semi-rural site, UHC filter. I've been repeatedly astounded how bright this is in ultra widefield (~14mm) shots, so I decided to go closer. But no flats, which seem to disagree with this lens (pity), and no darks cos I forgot. Still...

Nice shot. It looks a little overprocessed...saturation is a bit harsh, and the stars have that funky halo around them. I'd pull back on the processing a bit, reduce saturation...and that would actually probably help bring out more subtlety in nebula detail.

Out of curiosity, how long was the exposure?

Ah, the haloes are due to using a very wide aperture with the UHC filter, which they're not meant for. I get big red haloes round the medium-brightness stars, so I use 'remove colour fringing' in Lightroom, but that does leave these grey haloes, which isn't what I'd prefer, but it's a limitation of my setup at present. I'd like to stop down to reduce this, but I can't afford the light loss, as my tracking won't go beyond 1-2m mins per subframe. Also using this lens wide open creates all sorts of weird colour casts across the image, so it needs a bit more processing than the 100L Macro, for instance. The upshot is you get a lot more faint stars.

I rather like the saturation, though I can understand why some would tone it down. It's always a tough balance. This is 113x1min exposures at f/1.2 (50D @ ISO 1600)

You should look into getting Astronomy Tools. It's a set of PS actions that might help you with your halo problems. It's pretty cheap, around $20.

I don't have Photoshop, I use Gimp. It's a lot of work, but the opportunities to shoot the night sky are so rare, it's not so bad - I can set aside a day or two every couple of months. Thanks though. I've found a better tracker, so I might well be able to use narrower apertures. Also, Astronomik have released full frame in-camera filters, so that should help too.

Have you tried just stopping down a third or two thirds of a stop? Quite often, with fast aperture lenses, that's all that's really necessary to clean up the bulk of optical aberrations.

That said, I'd get a better tracker regardless. The longer you can expose, the better. Signal strength is really the key thing that matters. Every time you reduce ISO by a stop, you can expose for twice as long. Going from say ISO 1600 to ISO 400 means you quadruple your signal strength, while only doubling your noise.

 

[epsiloneri]

Re: Deep Sky Astrophotography

Nice image, and good to see that the 7D did not completely cut out the H-alpha. H-alpha regions must be some of the harder objects to image with a non-modified dSLR.

... I hate to feed your maniacal ego though...

You know, you've been taking little jabs at me like that for days.

Hehe... he actually gave you a compliment, although his German way of expressing it hides it pretty well ;D

 

[eml58]

Re: Deep Sky Astrophotography

So, I FINALLY got some clear sky for a period of several hours, and was finally able to create a nicer image of Horse Head and Flame Nebulas:

Superb, simply superb.

Really, this takes dedication few of us have, well done.

 

[CarlTN]

Re: Deep Sky Astrophotography

... I hate to feed your maniacal ego though...

You know, you've been taking little jabs at me like that for days. I'm not really sure what set you off, but so long as you continue to slip little insults into your responses, I really have no reason to spend time responding to your questions. This isn't a thin-skin thing, either. It's simply a matter of principal. If you have a bone to pick with me, pick it, in PMs. Otherwise, just be cordial out in the public forums...that really isn't asking much.

Sorry to hurt your feelings, I will try to do better next time.

 

[jrista]

Re: Deep Sky Astrophotography

Nice image, and good to see that the 7D did not completely cut out the H-alpha. H-alpha regions must be some of the harder objects to image with a non-modified dSLR.

The Astronomik CLS filter helps there. You have to expose for longer, but modern DSLR sensors don't completely cut off the deep reds. Less than 20% at H-a and even less at S-II get through, but over a long exposure duration, enough gets through that the red emissions get above the read noise floor.

... I hate to feed your maniacal ego though...

You know, you've been taking little jabs at me like that for days.

Hehe... he actually gave you a compliment, although his German way of expressing it hides it pretty well ;D

Being called a Maniacal ego maniac isn't a compliment where I come from...

... I hate to feed your maniacal ego though...

You know, you've been taking little jabs at me like that for days. I'm not really sure what set you off, but so long as you continue to slip little insults into your responses, I really have no reason to spend time responding to your questions. This isn't a thin-skin thing, either. It's simply a matter of principal. If you have a bone to pick with me, pick it, in PMs. Otherwise, just be cordial out in the public forums...that really isn't asking much.

Sorry to hurt your feelings, I will try to do better next time.

LOL. Again, my "feelings" aren't hurt. You have had a persistent issue with anyone who ever dares to contradict your opinions in any forceful manner. It isn't just me, Neuro has been on the other end of it just as much, if not more. You have a serious ego problem yourself...although yours has nothing to do with being to big, it really has to do with you being a weakling when it comes to confrontation or a conflict of opinions, especially when our presented with facts that you cannot counter because your own are FLAWED. You want to confront me, Carl? CONFRONT ME! I'm sick and tired of pussyfooting around with you. Buck up, be a man, and speak your friggin mind. Enough of this pathetic taunting from the corners. It's just plain sad.

And just to be exceptionally clear on this, because you seem to have misunderstood in the past, you and I are not friends. We never have been friends. We never will be friends. I deal with you because everyone deals with you. We all have to DEAL with you. Beyond that, your a persistent pain in the ass, always whining, always flinging sad little insults from the periphery, unable to cope when your proven wrong...at which point you resort to everything other than the cold, hard, painful facts...to mind games and button pushing and whatever else you think might somehow trip the other person up. It's very trollish, actually.

So, either lay it on me, or just shut up. Because otherwise I'm just done dealing with you. It's a waste of time.

 

[CarlTN]

Re: Deep Sky Astrophotography

So, either lay it on me, or just shut up. Because otherwise I'm just done dealing with you. It's a waste of time.

It's good to see you are not angry with me, glad to hear that! Yes Jrista, you are not a maniacal ego maniac whatsoever, and you are not out to get off on proving everyone wrong, and how smart you are. You are not an immature self absorbed child whatsoever, are you? Nor were your feelings hurt (obviously). Since you're done dealing with me, that's fine, because I wasn't offering any deals, so we can both win on that one.

I'm not sure what you'd like me to do, are you proposing marriage? I'm sorry, but I just can't relocate right now, and also, even though some say I wear pink tights...I actually don't swing that way (believe it or not).

I wasn't aware we were arguing about anything (photographic or otherwise), and as for me being wrong. I'll admit it when I am. And when I don't admit it, my posts just get deleted anyway. So you probably won't have to worry about this one for long.

I'm glad we could have this little chat, though. I feel so much better. Hope you've taken some more nice astro shots. This stacking method gets around the need to remove the IR filter, as you said, so that's good. However, the shooting and processing time is longer, isn't it? And the final output resolution is lower.

How much of a price difference would just buying a telescope with a cooled CCD imager cost? Couldn't you get like a 6 or 8 inch scope for like $2k to $3k, and a quite decent imager for less than $10k? Total cost would be similar to maybe, I don't know, a grand or two more, than your 7D and 600 ii combo.

Either way though, some of the results you're getting are nice to look at.

 

[jrista]

Re: Deep Sky Astrophotography

So, either lay it on me, or just shut up. Because otherwise I'm just done dealing with you. It's a waste of time.

It's good to see you are not angry with me, glad to hear that! Yes Jrista, you are not a maniacal ego maniac whatsoever, and you are not out to get off on proving everyone wrong, and how smart you are. You are not an immature self absorbed child whatsoever, are you? Nor were your feelings hurt (obviously). Since you're done dealing with me, that's fine, because I wasn't offering any deals, so we can both win on that one.

Well, there we go! At least I got an honest, unmitigated, clear and open opinion out of you. I'm not surprised about it, either. I suspect you would say the same thing about Neuro as well. I also suspect that most people would believe your wrong on all counts, about both of us, and anyone else you might have such a similar opinion of. But wow...good to have the air cleared! Maybe we can leave the underhanded sideline insults behind us now, and move on...? (Of course, you'll always be free to dish it all out in PMs if you just, you know, feel the hankering, and really, PMs, so everyone else doesn't have to "deal", you know?)

How much of a price difference would just buying a telescope with a cooled CCD imager cost? Couldn't you get like a 6 or 8 inch scope for like $2k to $3k, and a quite decent imager for less than $10k? Total cost would be similar to maybe, I don't know, a grand or two more, than your 7D and 600 ii combo.

Alright. First, I am spending my precious personal time here not because I'm some maniacal egomaniac troll who gets his LULS from proving people wrong. I spend my time writing things like this for the simple purpose of sharing my knowledge (with the honest intention of helping others expand their skills or improve their knowledge), and to correct misconceptions, debunk myths, and otherwise root out the twisted and convoluted "factoids" that many anti-fans may spew in order to trick unsuspecting readers into thinking something that is just plain and simply not true. I have said this in the past, but I'll say it again, because it's true...I really don't care what people think of me.

I care what people think, about information, the information they may be presented with and the context and other parties involved in an exchange of information, and when people misuse information to misinform and twist the facts, that bothers me. It happens a lot. We have quite a few members on this forum who just LOVE to twist and convolute the facts, either because they just despise the brand we all come here to talk about (i.e. Mikael) or because they have an agenda. THAT is why I persist in my extensively long, highly detailed posts. It isn't about me...it's really just about the facts. And that isn't for my own good...it's for the good of those who might actually take the time to read what I write. I want people to be well-informed about the facts, or educated enough to make a good judgment about subjective material when it arises (this is, after all, a rumors forum.) If you disagree, and truly think I'm wrong, and have the evidence to back up your opinion, prove it! I think I've proven myself that I'm quite capable of accepting when I'm wrong when proper evidence shows that I'm wrong. I have never claimed to be infallible (which is something an egomaniac WOULD do :).



This is for anyone reading this, not just Carl:

If you are interested in getting into astro, the kind of equipment you've mentioned is pretty costly. For one, once you get into the realm of cooled CCD imagers, your into the realm of buying each piece individually. You need a mount, a scope, an imager (and all the related accessories), as well as the appropriate guiding equipment (unless you REALLY go all-in on the mount). And you need the kind of quality equipment that will allow you to take full advantage of a cooled CCD imager.

(...bleh, I'm re-stacking my image, and it's sucking up all my cpu....letters are trickling onto my screen at a rate of about 1-2 every second...)

A really low end CCD imager might cost you a few hundred bucks. A single-stage cooled CCD is going to be around a grand, however single-stage doesn't always cut it...it can't always combat ambient temperature well enough to maintain a constant temperature, which is really what it boils down to. You don't just want cold, you want constant cold. For that, you need a two-stage TEC system, and that bumps the cost up to around $3000. Once you move into the realm of cooled CCDs though, most of those are monochrome. That means you need a filter wheel. Those can cost a couple grand themselves, especially the ones with pre-filter off-axis autoguiding capabilities. The autoguider itself is likely to cost another grant. So were talking about $5000 to $7000 for a midrange 2-stage peltier-cooled CCD camera with filter ring and off-axis guider.

If you really want to go balls-to-the-walls, you can pick up either a full-frame CCD sensor (same 36x24mm size as FF DSLRs) or a large 4096x4096 square imager. These tend to run somewhere between $10k and $45k. Some of the larger square sensors use three-stage cooling with an additional watercooled option for the third stage. The sensors of the highest end models are often medium format sized. Pixel sizes can be as large as 9µm!

As for the scope, there are a hell of a lot of options. You can pick up an Astro-Tech 6" Ritchey-Chretien Astrograph for about $400. That is the same aperture diameter as my 600mm lens, however the f-ratio is f/9, rather than f/4. That is more than two stops, meaning you need exposures at least four times as long. My image above was done with 180 second (3 minute) exposures. You would need to go full 10 minute (600 second) exposures with the AT6RC. Getting longer exposures like that requires not only good equipment, but you also have to align that equipment extremely, extremely well (and it's best to use an off-axis guider (OAG).

You can get a cheap OAG like Orion's and use it with an SSAG, and you might spend less than $1000, but since were talking cooled CCD imaging, your probably in the $5000-$7000 CCD range now anyway. You really want a better OTA than the AT6RC to take full advantage of that fancy imager. There are larger scopes that will do the job. The Celestron EdgeHD 11" is one of them. It clocks in at around $3300, just for the OTA. It needs a mount capable of handling at least 40lb capacity (80lb with weights.) The Astro-Tech 12" Ritchey-Chretien Truss, a newly released truss-type cassegrain, runs for about $4500. It's the cheapest truss astrograph on the market, and uses the Ritchey-Chretien design used in all the huge multi-meter cassegrain type scopes in professional and university observatories.

You can also move to the next step up, the AT16RC Truss, which runs about $7000. Now with a scope like this, your into the realm where you can really take FULL advantage of a cooled CCD imager. The Truss design handles issues like flexure very well. It reduces weight, since you don't have a closed tube consuming materials. The open design eliminates temperature issues...as the air cools, you don't have to deal with a temperature gradient between outside and inside air. This reduces extraneous sources of tracking imperfections that affect the stability of your stars and their position on the sensor for longer exposures.

Beyond the AT16RC Truss, you move into the realm of RCOS and PlaneWave scopes. They also use the truss design, RCOS uses Ritchey-Chretien (RC) type mirror design while PlaneWave uses the Corrected Dall-Kirkham (CDK) type mirror design. These are the top two mirror designs for high end scopes, and they both have their strengths and weaknesses, however PlaneWave's CDK design seems to produce some of the best on and off-axis spots in the market. For wide-field imaging (where you don't intend to crop, rather you intend to use every square pixel of every image that comes out of the scope), where corner performance is just as critical as center performance, RCOS and PlaneWave are the best choices, as they offer some of the best off-axis performance on the market. You pay for it, however...as these scopes tend to START at around $15,000, and can be as high as $200,000.

Finally, you need a mount that will support your equipment. Working backwards from the high end, you have ASA mounts, Astro-Physics mounts, Software Bisque's Paramount, and 10Micron mounts. These all cost about $10,000 for the low end, and as much as $50,000 for the high end. They can handle scope capacities of 100lb to several hundred pounds (which is often the case with the larger RCOS and PlaneWave scopes.) ASA makes some of the most precise and accurate mounts in the world. The lowest end mount from ASA that might handle a PlaneWave is about $20,000. Their mounts have an intrinsic error rate that is less than 1" (one arcsecond), lower than any mount from any manufacturer listed. Mounts from Astro-Physics, Paramount, and 10Micron cost about the same, and offer similar performance (although most require periodic error control or PEC to be programmed and enabled first, or the addition of absolute encoders, which greatly increases cost). 10Micron mounts are a nice middle-ground. They always come with built-in absolute encoders, so they offer not only high tracking accuracy and precision, but they can also compensate for issues like wind, or can pick up exactly where they left off if there is a power loss (most other mounts must first "sync to home"). If your using an RCOS or PlaneWave, you are going to be using one of these mounts.

The next step down would be the high end of the midrange mounts. This is the Celestron CGE Pro and the Meade LX850. These mounts are not as precise as the top end mounts listed above, but they will give you good tracking accuracy, and with PEC offer precision under 2". They both offer sync to home behavior, so if your using bigger equipment (i.e. scopes larger than 9-10") that need a more "permanent" installation, they are the cheapest options that meet the criteria. They can handle scopes and other equipment weighing up to 90lb. These mounts cost about $5000. Astro-Physics also offers a $7000 mount called the Mach 1 that offers most of their high end quality and precision, however it is only capable of handling 45lb of scope and accessory weight, so it is often not an option for larger scopes. It'll handle the Celestron EdgeHD 9.25 or AT8RC well enough.

The mainstream mounts that most amateur astrophotographers use are the Celestron CGEM, Orion Sirius and Atlas, SkyWatcher EQ-6, and iOptron iEQ45 and ZEQ25 (and probably the forthcoming CEM60). These mounts cost in the range of $1000 to $3000, and usually have capacities ranging from 20lb to 60lb. They can handle most of the entry-level and midrange scopes, including things like Celestron's EdgeHD 9.25" and even EdgeHD 11", AT6RC, AT8RC, maybe AT10RC, Meade's counterparts to Celestrons EdgeHD scopes, etc. They will also handle most of the refracting scopes on the market with the exception of a few, such as Officina Stellare's larger refractors (and probably most of their reflectors.)

So, you have three major brackets of equipment that would work for cooled CCD imaging...low end, midrange, and high end. You can probably split midrange and high end into two sub brackets:

Low End (for astrophotography):

$1000 Orion Sirius EQ-G Mount
$400 Astro-Tech 6" Ritchey-Chretien OTA
$1200 Atik 420C Color CCD (cooled, ~30°C Delta-T)
$425 Orion SSAG 50mm Mini Autoguider
-------
$3,025

Lower Midrange:

$1500 Celestron CGEM or Orion Atlas EQ-G Mount
OR
$3000 iOptron CEM60
$1300 Celestron EdgeHD 8" OTA
$4300 SBIG STF-8300 Mono + 5 slot Filter Wheel (remote controllable) + LRGB color filters + OAG (cooled ~50°C Delta-T)
--------
$7,100-$8,600

Higher Midrange:

$5000 Celestron CGE Pro or Meade LX850 Mount
$4500 Astro-Tech 12" RC Truss OTA
OR
$7000 Astro-Tech 16" RC Truss OTA
$5500 SBIG STT-8300 Mono + 7 slot Filter Wheel
$950 Astrodon LRGB Filters
$725 Astrodon OIII (Oxygen 3) 3nm Narrow Band Filter
$725 Astrodon SII (Sulfur 2) 3nm Narrow Band Filter
$725 Astrodon Ha (Hydrogen-Alpha) 5nm Narrow Band Filter
--------
$18,206 - $20,625

Lower High End:

$15000 10Micron 1000HPS or Paramount MX or Astro-Physics 1100GTO
$7000 Astro-Tech 16" RC Truss OTA
$5500 SBIG STT-8300 Mono + 7 slot Filter Wheel
$950 Astrodon LRGB Filters
$725 Astrodon OIII (Oxygen 3) 3nm Narrow Band Filter
$725 Astrodon SII (Sulfur 2) 3nm Narrow Band Filter
$725 Astrodon Ha (Hydrogen-Alpha) 5nm Narrow Band Filter
--------
$30,625

Ultra High End:

$33000 10Micron 4000HPS Mount w/ Absolute Encoders
OR
$37000 ASA DDM160 Mount
$50000 24" PlaneWave CDK OTA
$2000 Digital 10 filter Filter Wheel
$800 MoonLite CSL 2.5 inch Large Format Crayford SCT/RC Focuser w/ digital motor & accessories
$35000 Cooled Kodak KAF-16801 CCD, ~65°C Delta-T, 16mp 9µm 4096x4096 37x37mm sensor [Many manufacturers use this sensor, SBIG, FLI, etc.]
OR
$37000 FLI Cooled E2V CCD42-40 Back-Illuminated, ~65°C Delta-T, 4.2mp 13.5µm 2048x2048 28x28mm sensor
OR
$37000 FLI ProLine Kodak KAF-4301E Class 1 CCD, ~65°C Delta-T, 4.3mp 24µm 2048x2048 50x50mm sensor
$950 Astrodon LRGB Filters
$950 Astrodon OIII (Oxygen 3) 3nm Narrow Band Filter
$950 Astrodon SII (Sulfur 2) 3nm Narrow Band Filter
$950 Astrodon Ha (Hydrogen-Alpha) 5nm Narrow Band Filter
$950 Astrodon Ha 3nm Narrow Band Filter
----------
$125,550 - $131,550

 

[jrista]

Re: Deep Sky Astrophotography

With the low end rig, you are going to have a tough time getting the kind of image I did, not because I'm good (I'm not.) You need to very precisely align and calibrate your mount to be able to track accurately for a long time, because of the small aperture. You would need to be able to track stars for at least 10 minutes without "drift" (something you can correct for with drift alignment, a painstaking process). You really wouldn't be taking advantage of a cooled CCD there, so I really would just recommend using a DSLR. Save you some money (especially if you already have a DSLR). Use an Astronomik CLS filter with Canon DSLRs, and you can even shoot under the light polluted skies of the city.

Once you get more serious than a $400 OTA and a DSLR, you can move up the line to higher and higher grade setups. It starts getting more expensive once you get into monochrome CCD territory, because you have to use filtration. (Unless your just interested in pure monochrome imaging, some people do that.) Filters for astro are like filters for normal photography...you get what you pay for. Astrodon and Baader Planetarium make some of the best filters. At the very least, you would need LRGB filtration to use a mono CCD. If you live under light polluted skies, narrow band is the better option, as it cuts out ALL of the pollutant light, however narrow band imaging is much tougher...you still need very precisely aligned equipment, and you need to expose for at least 10 minutes, often as much as 20-30 minutes. Generally speaking, a CGE Pro or LS850 are BARELY going to get you more than 10 minutes unless you have exceptional skill at aligning. You need to move up to the high end mounts, especially those with absolute encoders, to really get the kind of tracking necessary for good narrow band imaging. Narrow band is a lot tougher to process in post as well...you have to do something called mapped color, where you map the SII, Ha, and OIII wavelengths to the red, green, and blue channels. But it isn't really just that simple, you have to make sure the images blend smoothly into each other...it's pretty advanced stuff, but the results are truly amazing.

If you move beyond 8-9.25" scopes or medium sized refractors (refractors are good, but these days generally don't have nearly the aperture of reflectors, or they do, it's just ultra costly, similar cost to the 600mm f/4 L II lens), then your really looking at a "permanent" setup. You are then either planning to build an observatory on your property, or build or rent one at a remote location like New Mexico Skies, where you can have remote computer control and high end robotic mounts (Paramount, ASA, 10Micron, Astro-Physics) under skies that are always dark, always away from light polluted cities. This is what a lot of serious amateur astrophotographers do, though...you would be surprised how many have about $20k to $30k in equipment and have built their own observatories on their land. All things considered, if your serious about normal photography, like wildlife or sports, you've probably spent about that much on your photography equipment (I know I've spent a little over $20k on my photography equipment.) So, while it sounds like a lot...it actually isn't all that much more than most people spend on their hobbies anyways (and, in many respects, a LOT cheaper than many hobbies...some people spend hundreds of grand on their "Fix up that old muscle car" hobby or their watersports hobby or whatever.) You can also kind of work your way up there as well. If you start with a really good mount, like the Astro-Physics Mach 1 or the iOptron CEM60, you have a very good mount that will last you for a very long time, and support most of the OTAs you might use (until you get up above the 10" cassegrain range...then you'll need something larger than a Mach 1).

There is another option for those who already own good normal photography equipment. The Canon L-series telephoto lenses make EXCELLENT telescopes. They rival high quality refractors like the Officina Stellare Hiper APO 152, which is a 6" (152mm) aperture just like the EF 600mm f/4 L II. The Hiper APO 152 costs about the same as well. Pretty much any Canon great white L-series telephoto can do the job, the old Mark I generation as well as the Mark II. You need to either get some custom parallax rings built to hold the lens into your mount, or get some ADM saddles and dovetail plates to bolt the tripod foot to your telescope. Along with some guiding equipment and a good midrange mount like the Orion Atlas EQ-G, and you have yourself a very high end setup capable of taking some amazing images.

The most popular lens to do this with, it seems, is the EF 400mm f/2.8 L Mark I. It's relatively cost effective, relatively long, has an ultra wide aperture so slapping on the 1.4x and 2x TCs gets you 640mm and 800mm focal lengths, which give you a good range with which to do moderately wide field astrophotography. (If you really want to use the 2x TC, it's best to go with the Mark II generation than the Mark I, but either will still do...the Mark I will just not be quite as pinpoint sharp, and will suffer from aberrations in the corners of the field.) The ADM saddle parts and necessary dovetail parts might cost around $350-$500. A basic guide scope, the Orion SSAG Magnificent Mini Autoguider, costs about $425. Along with the $1500 mount, and you have youself a pretty high grade astrograph setup. Obviously, this assumes you already have one of Canon's great white lenses...but with so many wildlife photographers around, that isn't all that unusual.

Even if you don't have a Great White lens, if all you have is a 70-200mm and a Canon 550D, you can still actually do quite a bit of astrophotography. You will need a good mount, the Orion Sirius EQ-G is a good place to start, however if you think you might eventually want to move up to a 6" or 8" scope, you should get the Orion Atlas EQ-G. You can mount the camera onto a V-type dovetail plate, which clamps into the saddle on the mount. Once you polar align the mount, you can then use the mount's hand controller and GOTO system to point your camera at anything in the night sky. You can then either just use a normal remote shutter release and bulb mode to take exposures...and they could be very long, up to a few minutes even (without guiding, much longer with guiding). You would be blown away at what a good old 85mm or 50mm or 24mm prime can do for you on a tracking mount. Those are your ultra wide field lenses, and they capture either the whole sky, or constellation-sized regions. The 70-200mm lenses and 135mm lens are also excellent for wide field work, although not quite full-constellation size. At 200mm you can zero in on just the Orion Belt and Sword region of the Orion constellation, for example. If you have a 400mm lens you can zero in on just the belt. If you have something like the Tamron 150-600, you can zero in on just the horse head and flame nebula region in the belt or just the Orion nebula region in the sword.

You can do a hell of a lot with just a lowly Canon DSLR, your existing lenses, and a $1000 tracking mount. At the very least, it's a place to start before you begin working your way up to that awesome $30,000 rig!

 

[CarlTN]

Re: Deep Sky Astrophotography

Having not even read all of that yet, and doubt I will tonight...let me just say that, I think you knew I was being sarcastic, because that actually is really what I think of you. And I know you think even worse of me, so I know you were also being sarcastic. But it's kind of fun to not let our personal mutual disgust get in the way of other important things such as photography.

I also wanted to say that, having not thought much about what I asked above (apparently), I can answer my own question with a simple answer (as in, why not get a scope instead, etc.).

(Besides the fact that you are a birder)...It's because you want a wider field of view than most telescopes provide, correct? I'm pretty sure most of the astro images I've seen, that needed a wider field of view, were not shot with telescopes, but rather SLR cameras and lenses.

Ok, I read some of the end of one of your posts. 9 micro meters for a pixel on a medium format imager...impressive. Would you happen to know what sort of imagers some of the well known observatories use? I'm sure it's probably customized, or "bespoke" componentry, but was just curious. I imagine the sensor is even larger than medium format. The one in the Hubble Space Telescope I assume, is quite large, but probably not the largest. Perhaps the "wide field" space scope uses an even larger imager (the one that hunts extra-solar planets, detects phase shifts from stars)...I think this is not even really called an imager, is it?

 

[jrista]

Re: Deep Sky Astrophotography

The Pleiades. The first few frames I managed to get on the first night I set up my telescope setup:

This was stacked from only a few frames, maybe 28. I had originally intended to take about 100 frames or so, but cloud cover and an accidental unplugging of my power cable ended up ending the night before it really got started.

 

[jrista]

Re: Deep Sky Astrophotography

Having not even read all of that yet, and doubt I will tonight...let me just say that, I think you knew I was being sarcastic, because that actually is really what I think of you. And I know you think even worse of me, so I know you were also being sarcastic. But it's kind of fun to not let our personal mutual disgust get in the way of other important things such as photography.

I also wanted to say that, having not thought much about what I asked above (apparently), I can answer my own question with a simple answer (as in, why not get a scope instead, etc.).

(Besides the fact that you are a birder)...It's because you want a wider field of view than most telescopes provide, correct? I'm pretty sure most of the astro images I've seen, that needed a wider field of view, were not shot with telescopes, but rather SLR cameras and lenses.

There are some very good short focal length refractors out there specifically designed for wide field work. There is also the HyperStar option for Celestron SCT scopes, which focal reduces them to f/2 instruments. If you have a 2800mm f/10 11" EdgeHD, and convert it with Hyperstar, you now have a 560mm f/2 imager...that is an even wider field than I get with my 600mm. Some refractors are as short as 400mm.

I think a lot of people DO use their camera lenses for very wide field work, for sure....although I think that is more a matter of convenience than anything. A good apochromatic 80mm f/4 scope (320mm focal length) can cost a pretty penny (several thousand), where as a 300mm f/4 camera lens might cost $1000 cheaper (although can still cost a thousand or two itself.) The actual apo 80mm f/4 refractor will be a much better device for imaging, and if y our serious about your astrophotography, it's the better route to go for wide field work (unless your talking Canon Great White telephotos, in which case until you get to the real high end range of apo scopes, the Canon lenses will be better.)

There are actually some professional scientific groups that use arrays of Canon lenses to do deep sky imaging. I know that EF 200mm f/1.8 L and f/2 L, EF 300mm f/2.8 L, EF 400mm f/2.8 L lenses have all been used in ultra fast (i.e. f/1!) telescopic arrays. Some have been used to find ultra dim deep field objects (super distant, dim galaxies), others have been used to find the dimmest nebula and galactic disc detail ever (the size of the average galaxy, according to some papers about an array that uses 12 EF 400mm f/2.8 L lenses in an f/1 setup, is significantly larger than is normally seen in your average visible light imaging...at f/1, you can gather so much light that you can see the dimmest structures in the universe with the exception of what Hubble itself sees.)

Ok, I read some of the end of one of your posts. 9 micro meters for a pixel on a medium format imager...impressive. Would you happen to know what sort of imagers some of the well known observatories use? I'm sure it's probably customized, or "bespoke" componentry, but was just curious. I imagine the sensor is even larger than medium format. The one in the Hubble Space Telescope I assume, is quite large, but probably not the largest. Perhaps the "wide field" space scope uses an even larger imager (the one that hunts extra-solar planets, detects phase shifts from stars)...I think this is not even really called an imager, is it?

Hubble has some large imagers, but its newer and more advanced ones are not all that large. Certainly not the largest.

A lot of professional observatories use PlaneWave scopes on Paramount ME II mounts with FLI imagers as the lowest end imagers they might use. There are some much larger imagers out there. Some have diagonals as large as 90mm, which is utterly massive, that's a 64mmx64mm sensor. These sensors also tend to have around 70dB of dynamic range. When you factor in a multi-stage watercooled TEC with a 70°C to 80°C Delta-T and read noise levels in the 0.001e- range, and they utterly blow the crap out of your average DSLR sensor or even a cooled $10,000 astro CCD imager. Imagers like that tend to cost a hundred grand a piece.

The larger PlaneWave scopes, including the $200,000 28", have become pretty standard these days for professional installations. They are usually set up as arrays and calibrated to point at the same locations in the sky synchronously. So, you might have an array of five PlaneWave 28" CDKs all with the high end 65mm or 90mm (diagonal) sensors. Your average multi-scope array setup for a university probably costs a couple million bucks, but in terms of combined relative aperture and sensitivity, such a setup can rival a mountain top observatory for total light gathering capacity, at a tenth the cost or less.

The largest telescopes on earth, like the Keck 10 meter, is an f/1.74 monstrosity. The Keck observatory houses multiple scopes, uses active optics, and dozens of imaging devices. I doubt any branded cameras were used...they probably use sensors from Teledyne, E2V, etc. and built them directly into the system.

 

[jrista]

Re: Deep Sky Astrophotography

Someone asked about the specifics of my exact setup, as they use a 500mm f/4 lens. Here they are, for those who are interested in getting started the same way I have:

HARDWARE

Mount:
Orion Atlas EQ-G | $1499

The mount is the most important part, hands down. Unless your going to dive head first into scopes larger than 11", you should be looking at the Celestron CGEM or the Orion Atlas EQ-G. I did a lot of research, spent almost a month on it. Celestron mounts are quite pretty, and they are actually manufactured by the same company that manufactures the Orion Atlas (which is the same as the Skywatcher EQ-6). Since it's introduction, however, the Celestron CGEM (and slightly larger sibling CGEM DX) has had some intrinsic gearbox problems, as well as a gear cogging problem. Celestron has done a couple things to fix these issues, however the gearbox is pretty fundamental to the design of the mount. There seem to be no real solution to the issue, which introduces a source of non-periodic error (or rather, periodic error, but at a different cyclic rate than the standard worm gear causes, and when the two converge & diverge, it creates a problem for autoguiding.)

The Orion Atlas is a very good mount. Feature wise, it's a bit better than the Celestron CGEM. It comes with a "dual" saddle built in. There are two main types of dovetails used with astronomy gear: The V-type or Vixen, and the D-type or Losmandy. D-type is much larger, much more stable, than V-type, and is essential for larger gear (like a 500mm f/4 lens.) The Orion always comes with a built-in polar finder scope (its situated in the right-ascension axis, and is used to align the mount itself with the exact celestial pole.) The polar finder scope is an add-on option for Celestron CGEM. The Orion polar finder scope comes with a built-in red LED to help you see the reticule diagram...the Celestron's add-on polar finder does not (although there are guides online that can help you solder in your own onto the mounts control board, if your up for it.)

The really nice thing about the Orion Atlas mount is that there is a good, high quality belt drive for it. Belt drives are what the higher end scopes use. Direct Belt Drive is what the ASA DDM (Direct Drive Mount) line of mounts use, and part of why they have exceptional accuracy and practically no problems with gear backlash. The existence of this upgrade (it costs a couple hundred) is one of the key reasons I purchased an Orion Atlas. I will be adding this upgrade in the future...from what I hear, it greatly smooths out the tracking and allows it to be more precise, with and without guiding. There are also other upgrades for the Orion Atlas, as well as a service called "HyperTuning" offered by DeepSpaceProducts (hypertuning is also available for the CGEM.)

My recommendation is to definitely get the Orion Atlas. When you get the atlas, also search for and buy an "EQDIR" adapter. EQDIR is a special TTL connecting cable that allows you to plug your computer directly into the mount, and control it with software called EQMOD. EQMOD is another bonus for the Orion Atlas that the CGEM does not have...very powerful, very capable software that can do everything the hand controller does, and much more. It also allows "plate solving"...more on that in a bit. (The EQDIR cable costs about $40.)

Saddle:
ADM D-series Side-by-side "Dual" | $249

ADM makes a number of accessories for astronomy equipment. I purchased the DSBS "Dual", or D-type side-by-side "dual saddle" model adapter so I could mount both my lens+camera as the "telescope", and also use an external automatic guiding setup with it's own lens. I'll get into that in a bit.

There are a number of saddle options, and a number of sbs saddle options. You can get V-type or D-type, or dual which takes both vixen and losmandy dovetails. I chose the dual, so that I would never have to spend more money adapting anything to my mount. It's $50 more expensive, but ultimately, it is going to be worth it, because it gives you more freedom to expand in the future. At longer focal length telescopes, you inevitably need larger guiding scopes.

Dovetail:
Astro-Tech Losmandy Style 7.9" | $50

I purchased this dovetail plate to attach my 600mm f/4 lens to the ADM DSBS saddle. There are a bunch of dovetail plates on the market. The nice thing about this one is that it has a slot down the middle, rather than a set of pre-spaced holes. The slot is essential to properly attaching your lens to the plate. With other dovetails, you are stuck either sinking your own hole for the second screw, or using a single screw...and THAT is bad news...one screw will not cut it, because as the mount moves the scope to track across the sky, its angle can change considerably...once it gets to a point where it is more parallel to the ground, a lens bolted to the plate with a single screw will easily slip...and that can potentially cause the whole entire setup, mount and all, crashing to the ground. On top of your lens. The overall weight of the entire setup is about 70 pounds...not even a Canon Great White lens would survive that.

Get this dovetail. Then, go to your hardware store, and buy some 1/4"-20 hex head screws with the small round heads that are about 1/2" long. The hex head ones with a small round head are important, because anything else is generally too large to fit into the slot on this dovetail, and will not hold the lens to the plate securely enough. Use those to bolt the dovetail to BOTH screw holes on your lens' foot.

Guider:
Orion SSAG w/ 50mm Mini Guidescope | $349

For a starter guiding package, you really can't go wrong with the Orion 50mm Mini Guidescope and the Orion SSAG (StarShoot AutoGuider). Don't get roped in by the "delux" version of this, which is about $70 more. All that ads is a helical focusing ring on the scope, however the scope can already be focused in two ways: Either by unlocking the front part that holds the objective and rotating it, then locking it again. Or by sliding the SSAG mini guider (which is really just a webcam sensor packaged with a logic chip that can control your mount through what is called an ST-4 port) in and out of the other end until your focused, then locking it down. Save yourself the $70, just get the Orion SSAG with 50mm Mini scope for $349.

There are other guiding options out there. The only other one I think is worth while is the SBIG ST-i guider. The SBIG is a higher quality guider, nice and compact, however it is a lot more expensive. Between a scope and the guider itself, you'll probably spend $800. The ST-i is really the option you want to go with if you eventually move to a full blown cooled CCD camera. The SBIG STF-8300M is a great midrange peltier-cooled mono astro cam, and in a package deal, you can get the cam, a filter wheel, as well as an OAG (off-axis guider) adapter that the ST-i plugs into. Off-axis guiding is generally more effective than external guiding, as it observes the sky through the same optical tube your imaging through. That allows it to correct for things like flexure. Flexure is one of the bigger problems with getting very precise guiding (essential at longer focal lengths, not really a problem at 200-1000mm). Flexure is the flexing...the bending and twisting...of an OTA (optical telescope assembly) as it is moved by the mount during tracking. It can result in elongation and wobble of stars that makes them look "unnatural" and "not round".

If you think your really going to get into astrophotography, and figure you'll eventually get a proper telescope (i.e. a Newtonian, SCT, or RC), then you might want to start with the ST-i. You can still attach it to an external guide scope (any smaller refracting telescope will work, or even the Orion 50mm mini guidescope).

Misc:
AC Power adapter for your DSLR (for use when your at home)
DC power adapter for your DSLR (for use with a deep cycle battery when your at a "dark sky" site)
DC power adapter for your laptop (for use with deep cycle battery ...)
2-3x DC cigarette plug with positive/negative clamps (for use with deep cycle battery...)
A 20-30 Ah deep cycle battery to power the mount at dark sky sites
A 100 Ah or larger deep cycle battery to power your camera and laptop

SOFTWARE

In order to effectively use the equipment above, you need the proper software. You need control software to actually control the camera and any other accessories (such as focusers and filter wheels, of your using them). You need stacking software. You need processing software. You will also need guiding software to make guiding actually work. Finally you will need planetarium software to tell the mount to point at various things in the sky.

Control Software:
BackyardEOS
Nebulosity
Sequence Generator Pro
MaxIm DL

Control software connects to the camera at the very least, possibly multiple accessories like a motorized focuser, robotic filter wheel, and even the mount. You use control software to frame, focus, and set up sequences for imaging. Imaging sequences can be light frames (i.e. 30x240s f/4 ISO 400 with lens cap off), dark frames and bias frames (with lens cap on), and flat & dark flat frames. Certain objects in the sky are exceptionally high dynamic range. Orion Nebula is the best example. Sometimes you need very long exposures, medium exposures, short exposures, and very short exposures, to fully capture the dynamic range. But in astro imaging, each "exposure" is ultimately an integration...a calibrated ((light frame - dark frame - bias frame) / (flat frame - dark frame)) image stack. So for each of those groups of integrations, you have multiple individual light frames, as well as the corresponding dark frames. You don't just take an image and then be done, like you would with normal photography. You can potentially take hundreds of individual frames of the same object, often over the course of several nights, just to make ONE image in the end.

Control software is essential. It takes a LOT of the tedium out of the process. Largely personal preference. I highly recommend looking into BackyardEOS and Sequence Generator Pro.

Guiding Software:
PHD2

In order to guide, you need guiding software. There is really only one option here, PHD2. MaxIm DL, the control software above, also supports guiding, but PHD2 is free and its the de-facto standard. It's highly capable, very easy (the acronym literally stands for "Push Here Dummy"!), and, free.

Stacking Software:
DeepSkyStacker
AstroStack
RegiStax
Images Plus
IRIS
[many others]

Stacking software is the first step in the post-processing stage. You bring in all your light, dark, bias, flat and dark flat frames. You configure the application for stacking. You register, then you stack. Sometimes the last two are part of the same step. Once stacked, you export an unmodified 32-bit TIFF, and your ready for the next step.

DSS, or DeepSkyStacker, is easy and free. Probably best to start there. There are a bunch of options here, with different capabilities for different purposes. Some are better for planetary stacking, some are better for galaxy and nebula stacking. Experiment.

Processing Software:
Adobe Photoshop
PixInsight

Processing software is what you use to "stretch" your integrations. Calibrating and stacking images into a single integration GREATLY reduces noise, and enhances dynamic range. If you understood the kind of noise levels and dynamic range levels that are fairly common in astrophotography, even the much vaunted 14-stops of DR that you get with a D800 would make you laugh at how pathetic that is! With a DSLR and a proper stack of dozens or even a hundred deeply exposed frames (several hundred seconds at least), along with dark, bias, and flat calibration, you can have well more than 14 stops of DR. If you were using a multi-stage cooled CCD imager, where dark current noise is in the 0.1e- or less range, after stacking your dynamic range from the darkest bits of dark nebula to the brightest pinpoint peaks of stars could be as much as 20 stops of DR, maybe even more (in which case, your most definitely using 32-bit float TIFF images, which are capable of storing what is effectively unlimited dynamic range, at least for the purposes of mankinds endeavors. )

Photoshop is pretty much a given. It's the staple of image processors, for everything. If you are a photographer and do not have PHOTOshop, then your a twit. Get it. You need it. There are thousands of tutorials, video and article, on the net that cover using Photoshop for processing astro images. There are bunches of PS actions for free and for sale that take care of common tasks that are just essential parts of stretching and enhancing astro images. You really can't do astrophotography without it.

PixInsight is the big 800 pound gorilla when it comes to editing astro images. It brings to the table a whole, broad range of mathematical tools that allow you to process your images in ways Photoshop could never even tough, using advanced algorithms that can deal with noise in ways you never even imagined, extract detail from the black background depths that are so deep you wouldn't have even imagined that you could imagine there being detail there at all. It even offers "pixel math", giving you the ability to apply any kind of algorithm you can imagine to your images, effectively allowing an infinite amount of ways to process, calibrate, color balance, stretch, extract, and otherwise enhance your images. Oh, and beware...it has a REALLY balls-to-the-walls on-crack brain-melding kind of wacked out UI design that will totally make you go BONKERS for the first few days...but that eventually passes.

Nothing beats PixInsight for astro editing. But you still need Photoshop, because there are still some things Photoshop just does better. You need both of these. (But start with Photoshop.)

 

[jrista]

Re: Deep Sky Astrophotography

Close-up crop of Flame, Horse Head, IC2023:

 

[CarlTN]

Re: Deep Sky Astrophotography

Thank you for all the details, very interesting and impressive! I must say, the most interesting part from the perspective of photography and photo lenses, is the arrays of them you are talking about. How does that work? Do they each feed their own imager that is then digitally summed somehow, or is it mechanical, using prisms or some kind of mirrors to reflect it all into one imager?