October 23, 2014, 01:28:31 PM

Author Topic: jrista et al, Why Astrophotography?  (Read 4034 times)

Larry

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jrista et al, Why Astrophotography?
« on: March 22, 2014, 01:03:41 PM »
Nothing I say here is meant to be critical or disapproving, it is an honest inquiry in an attempt to understand the appeal of this type of photography.  :)

I seem to be motivated primarily by a desire to capture scenes that are in some way unique or especially attractive, at least to me, and prefer that they be something real, as nearly as possible representing what was seen. By this I mean as a "standard human being" might happily experience some personal discovery of natural beauty. The image hopefully allowing an after-the-event reasonable facsimile sharing with others who were not present to hear "Wow, look at that!".

Here is my (very)limited understanding of astrophotography;

One sets up an unusually specialized and expensive amount of gear (scope, camera, filters, cooled sensor, tracker,etc.) …then goes through a usually quite complicated post-process (stacking, etc), and, if successful, ends up with an image which is practically identical with thousands of other photos of the same subject, taken from the same distance, with the same perspective, and in "enhanced"colors which vary according to the processor's taste, and may be nothing at all like the view of the subject which a space ship passenger might see with his own eyes, if close enough.

If this is a roughly correct description of what is going on,  it seems that only the basic form/density(ies) of the subject is actually captured, with the rest of the visual impression being more or less filter-effect digital artwork.

Add to these thoughts the fact that most all of the popular targets have "been done" in a practically un-matchable manner by Hubble, and I, personally, am left with a sort of "What's the point?" feeling.

I can understand the satisfaction of meeting the technical challenge of doing it oneself, …but beyond this, I am puzzled by the appeal vs. effort vs result factors.

More power to those who enjoy this type of photography (I agree that the results can be quite beautiful, taken at face value), but If comments are possible without ruffled feathers, i would appreciate some educating, …as i seem to be missing a gene re something that for many seems to be quite a passion.

Happy to have my vision broadened, and any errors above corrected.  ???

Thanks! 
« Last Edit: March 22, 2014, 11:28:24 PM by Larry »

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jrista et al, Why Astrophotography?
« on: March 22, 2014, 01:03:41 PM »

Don Haines

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Re: jrista et al, Why Astrophotography?
« Reply #1 on: March 22, 2014, 01:07:18 PM »
I have always been fascinated with the night sky. When I go on canoe trips I try to find campsite where I can lie out and stare upwards...  I built a floating platform where I can lie down in the evenings at home and stare upwards.... For me, astrophotography is a natural extension of that fascination.
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SoullessPolack

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Re: jrista et al, Why Astrophotography?
« Reply #2 on: March 22, 2014, 07:09:08 PM »
I'll offer my opinion.  Just for the record, I'm not the most knowledgeable of people on this topic, and I do prefer wide angle astrophotography to deep sky astrophotography, however, I enjoy both.

One of the reasons I do it is to make an image "my own".  I understand that there are many images made of the same nebula, obviously with the same composition since we are all on Earth.  However, is the same not true for scenes such as Tunnel View in Yosemite?  The weather conditions do change, but not taking that into account, every year there are thousands of photographers who end up with essentially the same image.  All are in search of making that iconic shot "their own".  It's also part of the learning process, much the same way that everyone writes a "Hello World" program as their first foray into computer programming.  Even though there are countless versions available online for download, there's a certain satisfaction being able to say "that's my creation".

Secondly, I enjoy the technical challenge of it all.  My gear is not as advanced, but I still do things like image stacking and dark frames.  It's not as simple as just clicking the shutter and having your result.  The whole process of stacking and whatnot can lead to different outcomes, and it's always a challenge trying to create the optimal final product.  Similarly, I enjoy taking 100+ shot multirow panoramas.  To this date, I have yet to create one that is compositionally better than most of my regular one-shot landscape work, and part of this is from the reality that even in landscape not everything stays still for as long as it takes to make such a shot.  Even though 1000 pixel versions of my huge panoramas never look as great as my one-shot photographs, I enjoy processing them just as much, maybe even more.  There is a lot of work to do when working with that many images.  So to summarize, part of the enjoyment is the the challenge of putting it all together, almost like a puzzle.

Thirdly, there is a certain peace and serenity that comes from being out alone, under the stillness of the night and millions of stars, that you can't get anywhere else.  When imaging, I like to walk away from the camera and the sound of the shutter and just lay on the ground and stare up at the sky.  You can easily get lost in it.  Just last night, I was doing this, staring up at the bright speck in the sky called Jupiter.  Just a small point of light, but an immense planet that would swallow Earth so many times over.  Just thinking about the vastness of space, and how many years it took for the light from those stars to finally reach us.  I enjoy how mind boggling thinking about the size of space can be.  It makes me realize how insignificant we really are in the grand scheme of things.  To the universe, we are no different than an ant on the ground to us (and even more, really).  This itself makes me cherish everything about how wonderful life is.

I recommend you give it a try one day.  Find some place truly dark, and just spend a night underneath the stars.  You may not like it, or it may change your life, as it did for me  :)

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Re: jrista et al, Why Astrophotography?
« Reply #3 on: April 02, 2014, 11:33:38 PM »
Sorry for the late reply...I did not see this thread till now.

Don pretty much summed up the core of it: I've ALWAYS been fascinated by the night sky, by the cosmos in general, ever since I was a very young kid (I think I got my first telescope for Christmas when I was 6.) Astrophotography lets you, personally, "see" deeper than is usually possible, and in more vibrance and brilliance, than you can visually. That's definitely a big part of the draw...and extension of that childhood fascination with the sky that needed an active outlet.

Visual observation, even with some fairly hefty equipment (i.e. say a 12-14" cassegrain type OTA) is usually largely "gray"...color is very hard to discern until you get into the really gargantuan apertures. A lot of visual-only amateur astronomers build their own "Dobs", or Dobsonian-type truss-design telescopes, with apertures up to several feet. They are usually pretty basic in construction, have wood mounts and secondary mirror supports, use basic metal piping for the truss structure, and they grid their own mirrors (there are actually several mirror grinding parties combined with star parties that occur a couple times a year in the US, on where a guy will actually teach you how to grind your own mirrors). I've heard of some personal project dobsonians being up to 60" of aperture, there are even a couple here in Colorado that are around 40" of aperture. At those sizes, you can visually observe the universe in colorful glory, although it still isn't as detailed as what you can get with astrophotography.

When it comes to the repetition and "it's been done before" aspect, I think Soulless nailed it. This is nothing new in photography. Were all part of a VERY saturated population of people, and repetition is common with any kind of fixed subject photography. Particularly landscapes, I've seen the same scenes, image pretty much identically, from dozens if not hundreds of photographers. Monument Park? Horseshoe Bend? Zion National Park? Etc. etc. Being "unique" in the realm of landscape photography is extremely difficult...you have to set yourself apart with technique and vision, rather than subject, because every subject has already been photographed countless times over the last century.

I've noticed that architectural photography, and increasingly "stairwell" photography, are also beginning to suffer from this problem. (I love photos of stairwells and the like...especially some of the subway escalators of some of those really cool new European....but I'm beginning to see the same escalators photographed pretty much the same way over and over now...) So, I don't think that is a "detractor" to be assigned only to astrophotograph. Other forms of photography have the same issue. Were just part of a very saturated community...you have to move into the realm of action and maybe macro photography to get more unique images, however even then...once you've seen a couple dozen "Fly Eye" macro photos, you've effectively seen them all. Repetition, there isn't much getting away from it, and the only way to truly set yourself apart is with your technique and vision...don't just photograph a fly eye...photograph it with flare, do something unique with it, make it stand out and do it with the utmost precision and exquisite aesthetic....and you have yourself a wonderfully unique, interesting, likable photo that people will gravitate to. Despite the fact that it really ISN'T unique. ;)

Soulless covered the other reason I gravitate towards astrophotography: It's a great technical challenge! It's a challenge, period. Astrophotography is probably the most difficult form of photography, and certainly one of the most expensive if you really want to do it right. It's not just about pointing a camera, composing, and pressing the shutter. There is an extensive base of knowledge, about imagers, optics, telescopes, mounts, electronics, and a slough of software packages, that is necessary to start creating truly beautiful, detailed night sky images. This holds true for pretty much anything that requires an equatorial tracking mount.

Creating the base sub frames that are ultimately integrated into a final image is meticulous, detailed, and very interactive work. When you really get into astrophotography, it isn't just about pointing at some DSO, telling your camera to take X number of frames at Y exposure time and Z ISO setting. For the best detail, color, contrast, and depth, you use a monochrome sensor with individual color filters. You image "clear" luminance, red, green, blue for broad-band color channels. You can also image in narrow-band color, filtering out all but one emission line at a time for nebula, such as Hydrogen-Alpha, Sulfur-II, and Oxygen-III. If you really want to go all out, you also image in infrared, as IR produces more "translucent" images that allow distant background objects, such as galaxies, that are normally obscured by nebula or foreground milky way dust lanes, to be seen. For EACH of these individual color channels, you have to create multiple "sub frames", so you might expose 20x1200s Lum, 15x600s Red, 15x600s Green, 15x600s Blue, 20x1200s Ha, 12x1200s SII, 12x1200s OIII, and 20x1200s IR. That's a total of over 35 SOLID hours of exposure time. That does not include any of the additional time before you start imaging to set up, polar align, drift align, inter-exposure dithering and cooldown times, etc. Some subjects might require fewer exposures, some require considerably more...depends on exactly how dim they are. Some of the worlds top astrophotographers have put 60-80 hours of exposure time into ONE single region of the sky. And that is just getting the initial light-frames themselves! There is still more work to integrate them into a full-color image.

Astrophotography is a highly technical, very meticulous, and very detailed form of art. You aren't just pointing a camera, framing, focusing, and opening the shutter. Astrophotography is more like painting than photography...you have to have your final goal entirely planned out in your head ahead of time, you have to prep, you have to be meticulous about each and every color.

You mention that astrophotography is just "visual impression being more or less filter-effect digital artwork." That is the farthest thing from the truth. Good astrophotography does not apply a bunch of filter-effects in post to create some hyper-saturated image full of colors. That's cheap, it's a cop-out, and it isn't astrophotography. A properly done astronomical photograph won't have any effect filters applied at all. Everything you see is real. Most astro images are done in visible light, so most of it is what these deep space objects would look like to the naked eye. In many cases, saturation is a choice left up to the one doing the processing, and a lot of astro images are generally oversaturated, but very rarely is it "effect-filter fakery". Many astro images these days are what we call "narrow band mapped color", where imaging was done only in Ha, SII, and OIII. Those three narrow bands of light are then mapped to red, green, and blue to produce the kind of images you normally think of as Hubble images, or "false color" images (as while these narrow bands of color do exist in the overall spectrum coming from deep sky objects, they are too narrow to be represented accurately with just R,G, and B channels in an image). There is even a form of NB mapping called "Hubble Mapped Color", but one need not use the exact blending method as Hubble. Some imagers use Ha for red and SII for green, some use SII for red and Ha for Green. Some will perform a more complex blend that uses various mixes of Ha, SII, and OII for the red, green, and blue channels to create more unique results. In general, narrow-band images produce much higher contrast, especially between dark dusty nebula and brighter emission and reflection nebula, where as visible light images are less contrasty, but often a bit more vibrant. Finally, the most advanced imagers will often blend all seven of these different color layers together to produce some rather wild results. Some, as I noted before, will even bring in an IR layer to add a whole new measure of depth and transparency to visible and/or narrow band base image.

The incredible colors you see in astro images is rarely ever from effect filters. It's all detail and color that's there in the objects themselves, and different techniques to blend various color layers together bring out different colors and aspects of detail. None of that detail is fabricated...it is EXTRACTED. You might be surprised to find out that most astro images, after calibration and stacking, usually appear as almost pitch black. For all the dozens of hours you may spend exposing, all that exposure time does is produce images where all the color is packed DEEPLY into the utter depths of the lowest levels of your image. A properly calibrated and integrated stack has at least 20 stops of dynamic range, and when you stack enough, you can end up with more than that. It is becoming pretty common these days with the more advanced tools at our disposal to save our integrations as 64-bit IEEE floating point FITS images. A 32-bit IEEE floating point TIFF can store well more than 24 stops of dynamic range...a 64-bit floating point image is, for all intents and purposes, capable of storing an infinite amount of dynamic range (more than capable of storing enough DR that, if one figured out how, they could represent a dim, distant galaxy about to be occluded near the edge of the sun, while concurrently storing enough information to resolve details on the surface of the sun itself). The very vast bulk of astrophotography post processing is geared towards "stretching" those really deep shadows to lift all the detail up into a level range that is visible to the human eye. The rest of astrophotography processing is geared towards reducing noise (because when you lift an image by 20 stops, even if you stack dozens of frames to reduce noise and improve SNR, you STILL have lots of noise), and towards enhancing the detail that exists within the stretched image. You would be surprised at how often very fine structure that you actually capture in your images appears to be flat detail...it takes some careful, meticulous, and often highly mathematical processing to separate the various levels of that detail to make it visible...but not separate them so much that the results look over-processed in the end.

So, is there a massive imbalanced trade-off in "effort vs. results" when it comes to astrophotography? It depends on how you look at it. Is there a massive imbalanced trade-off in "effort vs. results" when it comes to oil painting? Sculpting? How about architecture? All of these endeavors, which are undoubtedly great forms of art, require a far more considerable investment up front, and throughout the entire process, in order to produce one single artistic creation in the end. Astrophotography is also, without question, a form of art. As much as it is called photography, I think it may be more appropriate to compare it to painting than photography, as when you get down to the foresight and vision, the preparation, and the very manual process of stretching and detail extraction, astrophotography feels more like painting to me than photography. Just like painting, you often have to spend hours focusing one one small area of your image, figuring out the various algorithms that will enhance that detail in just the right way. And, similarly, the kind of satisfaction you get in the end, after putting in all that effort, all that dedicated, meticulous care and attention into your artistic creation...it's wonderfully satisfying.



The only real drawback with astrophotography is the cost. People balk at the $6800 price tag of a 1D X, or teh $12,000 price tag of an EF 600mm f/4 L II lens. When you get right down to it, to do astrophotography well, $6800 is down right cheap! For me, my ultimate goal is to be able to produce images that approach the kind of quality you might see from Robert Gendler or Russel Croman. To achieve that level of imagery, you not only need skill, but you need the right equipment. Were talking $20,000-$40,000 mounts, $40,000 telescopes, $30,000 thermoelectrically cooled scientific grade CCD monochromatic image sensors, and robotic equipment like filter wheels, image rotators, and focusers (each of which can cost thousands of dollars each.) Were talking about $115,000 in equipment, and were still not done. This kind of equipment isn't portable, the mount weighs a few hundred pounds, the telescope (such as a 20" RCOS or PlaneWave) weighs a good hundred pounds or so, and all the other accessories pile on another couple dozen pounds. You need a permanent observatory, complete with remote operation capabilities, power, internet, etc., built under permanently dark skies, in order to use this kind of equipment. That's probably another $35,000 to $50,000. Throw in another grand or so in software, for good measure.

Without this kind of equipment, then in large part, some of what you've said, Larry, about astrophotography just being repetition, is kind of true. With the kind of equipment and setup above, you have the ability to image narrow regions of the sky very deeply, very precisely, and so long as it's all set up out under consistently, persistently dark skies away from light pollution, you can use it every time the sky is clear, from the comfort of your own home. The ability to image very narrow regions of the sky very deeply means you can, if you wish, find regions of the sky that are often only a few pixels of "most" astrophotography, and image them in extreme detail. A 20" RCOS or PlaneWave telescope is usually going to be around 3500-4000mm in focal length, and you can throw on a 2x barlow to make that 7000-8000mm. You can also use focal reducers to get a wider field (say 2700mm), image at a lesser magnification, and even do mosaic imaging to expose gigantic regions of the sky in exceptional detail.

Most of the astrophotography you'll see on the internet is usually what we call "wide field", where large multi-arc minute or even arc-hour swaths of sky are imaged all at once with a short focal length...200mm, 350mm, 400mm, 600mm. At these levels, the large scale structures are easily recognizable, their locations in the sky are well known, and you don't need as much total integration time to get decent results. And the brighter the structures are, such as Orion Nebula or Andromeda Galaxy, the more frequently they will be imaged by novice and moderately skilled amateur astrophotographers.

So there is a certain amount of "repetition" when it comes to astrophotography, more so due to a barrier to entry due to the excessive high cost of getting high quality, precise equipment that allows astrophotographers to pursue more unique targets. I doubt I'll ever be spending a hundred grand on astrophotography equipment, at least not all at once, however over the next few years, I don't think it's out of the realm of possibility to spend $35,000 to $50,000 on better equipment. I doubt I'll ever be able to afford a 20" RC Optical Systems (RCOS) Ritchey-Chretine ion-milled telescope. I also doubt I'd ever be able to afford a 20" PlaneWave CDK, which are a bit cheaper, different design, just as high quality...as even that still costs over twenty grand just for the OTA. To get serious at all, though, you have to purchase a mount that is capable of high precision, absolutely encoded, precision modeled, and permanent tracking. Such mounts are expensive, around $20,000. Once you have a mount like that, however, then your pretty much free to put any kind of OTA you want on it, and you can slowly upgrade to better and better OTAs over the years. By the time I retire, I might finally have a 20" PlaneWave CDK with a nice FLI ProLine 37x37mm 4096x4096 cooled CCD imager sitting on a nice 10Micron 2000HPS mount, and be capable of creating some of those unique images of narrow regions of the sky that most people just think of as "That little group of 50 pixels over there" in their images.

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Re: jrista et al, Why Astrophotography?
« Reply #4 on: April 09, 2014, 06:32:31 PM »

Larry

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Re: jrista et al, Why Astrophotography?
« Reply #5 on: April 10, 2014, 11:12:08 AM »
Does this question also apply to landscape shooters? 

http://www.coloradoplateauphototours.com/blog/wp-content/uploads/2012/10/Mesa-Arch-Scene.jpg

Yes, LOL,… I would not be a part of that crowd, any more than I would want to be elbow to elbow with other steelhead fishermen on opening day at a "hot" fishing hole. (…or part of the "New iPhone" madness outside the Apple store  ;-) I guess it depends upon what you are looking for in your experiences.

Larry

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Re: jrista et al, Why Astrophotography?
« Reply #6 on: April 10, 2014, 12:11:33 PM »
Sorry for the late reply...I did not see this thread till now.
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Wow! First let me say that I am delighted by the serious, thoughtful responses, with no raised feathers in evidence ;-)

Don and Soulless; I can relate, to a degree, to the flat on the back, staring-at and contemplating the night sky experience. The "degree" being such that I bought a nice small telescope (Tele-Vue 76 and a bunch of eyepieces, Wimberly head, etc.), and spent more than one "meteor shower" night on top of a nearby hill-top with eyes/tele/and binoculars, learning a basic few of the constellations and pondering the imponderables of "What's out there?"

I am amazed and awestruck by photos such as the "dime sized portion of the sky" content shown us by Hubble, …
and some of the recent TV programs about space are fascinating .

My willingness/ability to spend the time/money/study needed to get to the more satisfying capability-levels, vs. devoting the same to my other interests seem have dictated that this will be the limit of my personal astronomical exploration.

To each his own however, and I wish much pleasurable enjoyment to those who choose to delve deeper. ( I suppose there is such a thing as "dis-pleasurable" enjoyment, … but that is for the kinkier types ;-)

jrista,

I am stunned by the thoroughness of your reply!  :P  You have provoked a lot of thought indeed, …and enlightened me far beyond my previous limited understanding of "astrophotography".

I have some idea of the time and effort required to put so much meat into a response, and want you to know it is very much acknowledged and appreciated.

I relate most to your description of the involved processes as "art", satisfying in its challenges and the achievable results. I have all I can find motivation, time, and money for in my other interests -- guitar, art (hands-on, not computer) and most captivatingly, small boat design(also sans computer, …only old-fashioned calculator, eye, ducks and splines) which somehow relate to one another through the commonality of pleasing curves (there is something about the lines of a figure, a guitar, and a beautiful hull, that I find inspiring).

I especially note your comments that many of the astrophotographs closely approximate what the human eye might see, if properly placed in space. The belief that this was not so has been one of the factors in my feeling that these photographs were more fantasy than reality. Since I am more interested in what beauty actually exists to be seen, rather than in what fantasies someone might "imagine" for me, I was pleased by your statements.

I think that the series of images entitled (something like) "Powers of Ten", makes clear that a person could spend a lifetime observing and learning at any of the levels, and still remain ignorant of the universes contained within each of the others.

So, I guess it is appropriate that we each be guided by our own inner compass, in traveling our individual paths.

I would be interested to see the products of your efforts, or those of others of a like mind-set, which are achieved after both the $100,000+ investment in equipment you describe, and the years of study and experiment that would enable its competent use.

To all;

Thank you, again, for taking the time to give attention to my inquiry :)

Best wishes,

Larry


« Last Edit: April 10, 2014, 12:19:33 PM by Larry »

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Re: jrista et al, Why Astrophotography?
« Reply #6 on: April 10, 2014, 12:11:33 PM »

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Re: jrista et al, Why Astrophotography?
« Reply #7 on: May 10, 2014, 01:16:27 PM »

The only real drawback with astrophotography is the cost. People balk at the $6800 price tag of a 1D X, or teh $12,000 price tag of an EF 600mm f/4 L II lens. When you get right down to it, to do astrophotography well, $6800 is down right cheap! For me, my ultimate goal is to be able to produce images that approach the kind of quality you might see from Robert Gendler or Russel Croman. To achieve that level of imagery, you not only need skill, but you need the right equipment. Were talking $20,000-$40,000 mounts, $40,000 telescopes, $30,000 thermoelectrically cooled scientific grade CCD monochromatic image sensors, and robotic equipment like filter wheels, image rotators, and focusers (each of which can cost thousands of dollars each.) Were talking about $115,000 in equipment, and were still not done. This kind of equipment isn't portable, the mount weighs a few hundred pounds, the telescope (such as a 20" RCOS or PlaneWave) weighs a good hundred pounds or so, and all the other accessories pile on another couple dozen pounds. You need a permanent observatory, complete with remote operation capabilities, power, internet, etc., built under permanently dark skies, in order to use this kind of equipment. That's probably another $35,000 to $50,000. Throw in another grand or so in software, for good measure.


You don't necessarily need a 20,000-40,000$ mount when you have PHD and an autoguider.  ;)
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Re: jrista et al, Why Astrophotography?
« Reply #8 on: May 10, 2014, 01:32:34 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P

The point of a high end mount isn't really just about tracking performance, though. It's fundamentally about weight capacity. You can get up to around 8" scopes with lower end/midrange mounts that can handle 40-60lb. But to really be able to track properly, guided or otherwise, with larger scopes (12"+), you need a mount that can handle much larger capacities. Such as 90-110lb for 12-14" scopes, and around 130-200lb for 16-20" scopes. Larger scopes (larger physical apertures) are necessary to resolve more detail and resolve dimmer details.
« Last Edit: May 10, 2014, 01:34:36 PM by jrista »

traingineer

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Re: jrista et al, Why Astrophotography?
« Reply #9 on: May 10, 2014, 01:37:08 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P

What autoguider do you own?  :D

Weight is also an important factor, especially when you add up the counterweights/all other stuff. But I think most new astro-photographers aren't going to get telescopes that large/heavy.  :o
« Last Edit: May 10, 2014, 01:40:08 PM by traingineer »
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Re: jrista et al, Why Astrophotography?
« Reply #10 on: May 10, 2014, 02:31:21 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P

What autoguider do you own?  :D

See my previous reply. :P

Weight is also an important factor, especially when you add up the counterweights/all other stuff. But I think most new astro-photographers aren't going to get telescopes that large/heavy.  :o

Not new astrophotographers, no. But if your serious about getting good images, the sweet spot seems to be between 16-20" apertures, to maximize quality and detail. Things just get expensive because getting a mount that can handle that kind of capacity is just expensive. If your going to spend $10k-$20k on a mount, you might as well get a high end scope as well.

traingineer

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Re: jrista et al, Why Astrophotography?
« Reply #11 on: May 10, 2014, 03:41:06 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P

What autoguider do you own?  :D

See my previous reply. :P

Weight is also an important factor, especially when you add up the counterweights/all other stuff. But I think most new astro-photographers aren't going to get telescopes that large/heavy.  :o

Not new astrophotographers, no. But if your serious about getting good images, the sweet spot seems to be between 16-20" apertures, to maximize quality and detail. Things just get expensive because getting a mount that can handle that kind of capacity is just expensive. If your going to spend $10k-$20k on a mount, you might as well get a high end scope as well.

So a telescope like this Astro-Tech 406mm f/8 OTA?
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jrista

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Re: jrista et al, Why Astrophotography?
« Reply #12 on: May 10, 2014, 06:31:03 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P

What autoguider do you own?  :D

See my previous reply. :P

Weight is also an important factor, especially when you add up the counterweights/all other stuff. But I think most new astro-photographers aren't going to get telescopes that large/heavy.  :o

Not new astrophotographers, no. But if your serious about getting good images, the sweet spot seems to be between 16-20" apertures, to maximize quality and detail. Things just get expensive because getting a mount that can handle that kind of capacity is just expensive. If your going to spend $10k-$20k on a mount, you might as well get a high end scope as well.

So a telescope like this Astro-Tech 406mm f/8 OTA?

The AT16RC Truss is a good place to start. That sucker still costs $7000, but I'm thinking more of something like this PlaneWave 20" CDK (which is on an Astro-Physics 3600 GTO, which is designed to handle scopes up to 24" or so....I think an AP1600GTO or a 10Micron GM2000HPS are both sufficient to handle the 16/20" RCs and 17/20" PlaneWaves, though):



These 20" scopes (RCOS and PlaneWave ones) seem to hit the sweet spot for deep sky imaging quality, star spot size, field flatness, imaging circle size which are up to 70mm. (When you spend $20k on a mount and $35k on a scope, you then can't spend $2000 on a 22mm diagonal imager, now, can you! :P) The nice 37x37mm 4096x4096 9µm pixel imagers have a 52mm diagonal, and need larger image circles. Astro-Tech scopes, when fitted with a proper field flattener and focal reducer (they do not have a flat field intrinsically like an RCOS or PlaneWave), you get about a 40mm image circle. That isn't even large enough for a FF DSLR sensor, let alone a nice larger format square imager. The new generation of astro imagers coming out to the market have 65mm diagonals, and apparently even larger ones with 70mm diagonals are on the horizon.

A 16" Astro-Tech Truss on a Losmandy Titan (the mount in your picture, which is still $7000 in and of itself) is kind of like the low end of the higher quality scopes. It would certainly suffice for a lot of people, but your still talking about at least $14,000 of investment for just the mount and the scope in your picture. The Losmandy mounts must still be guided as well, and to actually maximize the image quality potential of a longer, 16" scope like that, you need really good guiding that isn't prone to differential flexure problems. So, now were talking about OAG (off-axis guiding), which means adding a quality OAG device with adjustable pick-off mirror to your imager (that's about another $800-$1000), a high sensitivity guide camera (so that it can find dimmer stars in the very narrow circular band of the field of view that a pickoff mirror can pull stars out of), and there is really only one: The Lodestar X2, which is another $700. You don't just twiddle your thumbs with an OSC imager when you get up to even AT16RC level scopes...so you want a mono imager with a filter wheel and some appropriately high quality filters. The mono imager is another $2000 at least, the filter wheel is another $1500-$2000, a set of LRGB filters is about $800-$1000 and a set of narrow band filters is another $1000. You probably want to upgrade the Losmandy mount with the higher quality worm gear and do some hypertuning, so another $500.

So, assuming we go with the low end 16" scope setup with an Astro-Tech 16" RC Truss and a Losmandy Titan, your grand total cost is still over $20,000. :\ Losmandy mounts are nice, but they are a pretty old design that hasn't been updated in quite some time. They are pretty pricey for $7000 (or so, depends on what accessories and counterweights you end up choosing at the time of purchase). The Losmandy mounts don't use any kind of high resolution absolute encoding, either...but absolute encoding is becoming a core feature of most of the higher end mounts. That makes their $7000 price even more difficult to swallow.

You can pick up the Astro-Physics Mach 1 GTO with high resolution encoding and PPEC (not quite as good as absolute encoding, but a hell of a lot better than what the Losmandy Titan offers), which is capable of doing unguided imaging up to 15-20 minutes, for $6000. The 10Micron GM1000HPS is about $9000, and it not only uses high res absolute encouders mounted directly on the axis (extremely precise for both tracking and pointing accuracy), it also embeds full blown sky modeling functionality right in the mount. Combining high res encoding with built in sky modeling via plate solving, and you have a mount that quite literally CAN NOT lose it's place.

The inability to lose it's "place", or to lose what it's pointing at in the sky, is a feature that becomes increasingly important the more you move into LRGB and narrow band imaging with a mono imager...you usually have to expose for long enough that at the very least, you run into a meridian flip each night (you image on both the eastern and western sides of the meridian), but you also usually need to image over multiple nights to get all the various channels. Without absolute encoding and plate solving, recentering your subject exactly as it was centered previously can be a very difficult process. It's not impossible to image over multiple nights without absolute encoding/plate solving, but once you integrate everything, you end up having to crop a fairly significant amount of sky around the center of your image because the alignment of each set of frame is offset relative to prior sets.

So, back to my original estimate. If your going to spend tens of thousands of dollars on equipment, it's best to spend the tens of thousands of dollars properly. Instead of a Losmandy Titan, get a 10Micron or maybe an ASA mount. It's more expensive, but the expense is WELL worth it, as those mounts are so good they effectively eliminate all hassles related to mount performance. They can also easily be used right up to their capacity limits, where as a Titan or CGE or other lower end mounts usually need to be used at half capacity for imaging work.

You could still start with an Astro-Tech 16" RC Truss. Personally, that's my plan, but over the long term, I think I'd ultimately move up to a PlaneWave 17" or 20" and a larger format CCD imager. Even assuming you stuck with the Astro-Tech scope, your cost is still up around $25,000-$27,000. The mount is really the centerpiece, the most important thing. Once you have the mount, you can slap on any number of scopes with a variety of different focal lengths, apertures, and fields of view to do all sorts of imaging. But even the $7000 Losmandy Titan, or for that matter the $500-$6000 Celestron CGE Pro or Meade LX200 mounts, you are spending a TON of money on a mount that MIGHT get an arcsecond better tracking once you PEC and guide vs. a "low end" mount like the highly popular Orion Atlas. Personally, my guiding performance with the Atlas is already within the limits of seeing:



This is an image of my PHD guiding graph around the last time I did some imaging (we've had clouds here for nearly a month, haven't done any imaging since). My total RMS is 0.81", and my P2P performance is around 2" (my seeing, or atmospheric turbulence here in Colorado, tends to produce stars around 3" - 3.5".) My mount, unguided, has a 15" P2P periodic error...I've been able to guide that out almost entirely. The $5000 Celestron CGE Pro has a 5" P2P periodic error, however even THAT expensive mount can only do about 2" P2P with it's PPEC and guiding. If you happen to get an excellent copy, you might get 1.5" P2P. The Losmandy Titan doesn't get much below about 2" either. Guiding is a little easier with the $5000-7000 mounts, because of their lower periodic error, but they all still suffer from high frequency PE, which is why you can't really get any better than 2" regardless of whether you spend $1400 or $7000. All of them have to be guided...and once you throw guiding into the mix, it isn't worth it to spend thousands of dollars on a mount just for more capacity.

A 10Micron or ASA mount gets 0.1" P2P tracking or better with PEC, and they can usually track unguided for at least 20 minutes, and many higher end imagers get them to track up to 30 minutes without guiding (20-30 minute exposures are pretty common for narrow band imaging). Even guided, you couldn't get 20-30 minute exposures with a Titan, CGE Pro, or Atlas.

No, you don't have to spend $20k or more. A lot of people get some pretty good results with only a couple thousand invested. But you can see a VERY clear difference in results between people who image with the lower end equipment, and people who, at the very least, invested in a true high end mount. You can take a Tak FSQ-106 (very popular APO refractor) and put it on an Orion Atlas and a 10Micron. Let the same guy do some imaging with both setups, and given his consistent skill, the images produced with the 10Micron will be superior. The effects of the poorer tracking (2" P2P or so vs. 0.1" P2P, a factor of 200x!) with the Atlas shows up quite readily in the quality of the stars and sharpness of detail. An arcsecond is only a fraction of the diameter of your average medium-sized star...but it's still enough to really kill off your star roundness, sharpness, and eat away at detail in nebula and galaxies. Swap out the $5000 Tak 106 with a $20,000 PlaneWave 17" CDK, and suddenly all the optical aberrations (for as good as the Tak is, it's still a refractor, and all refractors suffer from some abberations that show up in star fringes and flares and such...even my $13,000 600mm lens, which is as good as $10,000 to $20,000 APO refracting telescopes, still suffers from poor star shapes even when I stop down a bit) are gone and your star spots are simply sublime.

If quality is your goal, it's pretty tough to achieve it without spending at least $20,000.

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Re: jrista et al, Why Astrophotography?
« Reply #12 on: May 10, 2014, 06:31:03 PM »

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Re: jrista et al, Why Astrophotography?
« Reply #13 on: May 10, 2014, 06:40:08 PM »
I do have PHD and an autoguider. That only gets you so far. Especially with the Orion SSAG cam you shared. I have that, and it just isn't very sensitive. Better guidecams with enough sensitivity to really do better cost about $500-700. :P






If quality is your goal, it's pretty tough to achieve it without spending at least $20,000.


So my Astro Tech 72mm ED F6 Refractor scope and Ioptron ZEQ25GT CEQ mount wouldn't be "good enough" for quality astro photography?  :|
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Re: jrista et al, Why Astrophotography?
« Reply #14 on: May 10, 2014, 07:18:25 PM »
Let me try it this way. Have you seen images produces with PlaneWaves on Paramounts, AP mounts, and 10Micron mounts? Have you ever compared them with the images your AT72ED produce?

I don't mean to offend, honestly...but no, I do not believe an AT72ED and a ZEQ25 are going to produce IQ that even remotely compares to a PlaneWave or RCOS scope on a high precision mount. I spend a lot of time looking at peoples images on AstroBin. A LOT of people use the Astro-Tech refractors (well, a LOT of people use Astro-Tech scopes period, including me shortly here as I'm about to order either the 8" or 10" RC) because they are an extremely good deal for the quality you ARE getting. Even those who are quite skilled and know how to get round stars still can't get the kind of CLEAN stars that a PlaneWave gets you.

If you look around and compare what $3000 worth of equipment can produce in the majority of cases, vs. what $20k-$40k can do in every case...you'll understand where I'm coming from.

My $13,000 lens could probably serve me a hell of a lot better if I put it on a higher quality mount. I'd also probably get at least twice as much sky time out of it if I had it on a mount I did not have to constantly fiddle with to keep tracking smoothly, or to get pointed at the right place in the sky, etc. There are just things you have to deal with when using lower-end equipment that consumes a very considerable amount of time. I have a four hour window to image from my backyard, given how the trees and houses around me affect my line of sight. On any given night, I usually get about 2 hours of actual time imaging. The rest is spent fiddling with getting my polar alignment down to 1' or less, getting my guiding set up and running (If you have ever used the Orion SSAG with PHD, you would know how you have to first find an acceptable guide scar (which, with the really low sensitivity of the SSAG, is often a real PITA), then let it calibrate which, assuming you use the recommended ~20 steps, can take at least five minutes, then let it "settle" once it actually starts guiding), then get your focus dialed in, frame and center your subject, get your imaging sequence set up and finally get it started. If the temperature is changing throughout the night, you gotta keep an eye on your focus, so you usually produce about five subs, then refocus, produce five more, then refocus, etc. If ANYTHING happens to your guide star...a light high altitude cloud of just the right density moves over it, you can lose it, then you lose your guiding, and your tracking goes to hell (from 2" to 15" or worse!) You can automate a lot of this, but all these little things take time. Using SGP, you can automate your pointing, centering, dithering, guide recalibration, focusing, filter selection, etc. All of those things consume about 40% of that 4-hour window.

Now, throw in a high end tracking mount that doesn't need guiding at all. Suddenly, the only things you have to do every few subs now are check focus, and maybe choose a new filter. All the other cruft to make sure your still pointed at the right thing, still properly centered on it, all the guiding crap, etc. is just no longer necessary. Focusing can still take away some time, but not nearly as much, so you have the ability to produce a lot more subs during your window of opportunity each night. Having enough subs to stack and average out all the noise is one of the most important things that I see high end imagers doing differently. You might see people using lower end equipment getting 30 4-8 minute subs with a DSLR, when they need at least 100 to reduce noise to manageable levels. The guys with RCOS and PlaneWave scopes are getting 15-20 10 minute Luminance subs, along with 9-15 10 minute subs each for R, G, and B. That's anywhere from 42 to 65 frames, each of which are higher quality with more signal and better SNR, than the 30 low SNR subs the guys using modded 350Ds on Orion or Astro-Tech refractors. It's a total integration time of at least 650 minutes, vs. a total integration time of maybe 240 minutes or so.

I understand why imagers with AT72EDs and ZEQ25's or AT6RCs and Atlases using modded DSLRs or $700 Atik OSC CCDs don't get more than 2-3 hours worth of subs. There are very good reasons for it, not saying there aren't. It's a far greater effort, requiring a far more active investment to keep your setup producing subs that don't need to be culled and will contribute nicely to the final integration, when using lower end equipment. I think that just speaks volumes about why someone would invest some serious money into high end equipment if they want to take their imaging to the next level, where their stars aren't just round, but perfect, where their color saturation isn't just good, it's sublime, and where their detail is just mind blowing. ;)

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Re: jrista et al, Why Astrophotography?
« Reply #14 on: May 10, 2014, 07:18:25 PM »