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Author Topic: Deep Sky Astrophotography (Gear Discussion)  (Read 27702 times)

Don Haines

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Re: Deep Sky Astrophotography
« Reply #15 on: January 03, 2014, 12:23:48 AM »
Reprocessed a few times with DeepSkyStacker. Tweaking the final result is a real PITA, but when you figure out how to do it right, the results are much better:



I dunno if my experience is relevant, but I held out for as long as I could before I got a tracking mount. You can do good stuff with short exposures if you go through the proper motions of dark and flat frames, and stacking a lot. Dark skies/astro filters probably make the most difference beyond that. I do all my aligning and stacking by hand in Gimp (I'm not sure any of the good free astro stack/align software is available for Macs, but anyhow that's what I'm used to now). Having said that, a tracking mount can push things further than anything.


You can extract a certain degree of quality from non-tracked stacking, but there is a limit. With short exposures, you have a very low signal strength. While you can improve SNR with stacking, you can't improve the actual image signal strength beyond a certain point, so you can never get the nice fine detail that a long exposure gets you. I've spent about two months now trying...and the shot above is about as good as I think I'll be able to do without tracking (or exceptionally dark skies, which are really rare and hard to find.)

I have done a fair amount of manual stacking in Photoshop, and the results can be quite good. Stacking software, especially the more complicated versions like DSS, Nebulosity, etc. are much more capable, but they have a high learning curve, and often their toolsets are difficult to use. I have avoided DSS up till now, but I just spent the bulk of the day working on the shot above, and I think I finally have it figured out. It's a bit noisy (it got much too cold last night, and I packed it in before I took dark frames and bias frames), but that can easily be delt with.

Exposure times of tens of seconds up to minutes can be transformative.


Indeed! I can't wait to get my hands on the Celestron EdgeHD 11" CGEM DX. I had my eyes on a 5D III for my next photography, but I think I'm going to move the telescope to the top of my list. I am curious to see how the 7D II turns out, and for astrophotography, no DSLR will really do what I want, so I'm planning on getting a monochrome CCD with the biggest pixels I can find (probably around 9µm to 9.5µm, or perhaps 5µm with the option to 2x2 bin) an dual-stage peltier cooling (which gets you up to around 77% Q.E.) I'll then be able to filter Ha, Hb, Luma, R, G, B, and any other bands independently, and blend them in post for very high detailed, full-color wide band images.

It's -33C here tonight.... I'm not terribly worried about peltier cooling :)

I have an 8" Celestron with a tracking mount.... I have tried the 60D on it, but there is WAY to much noise... My friend's 5D2 work's much better, but it is an hour's drive away and that rules it out most of the time...

I have been thinking of getting one of these.... http://focusscientific.com/osCommerce/catalog/product_info.php/cPath/94_47/products_id/649
or
http://focusscientific.com/osCommerce/catalog/product_info.php/cPath/94_47/products_id/650

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Re: Deep Sky Astrophotography
« Reply #15 on: January 03, 2014, 12:23:48 AM »

jrista

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Re: Deep Sky Astrophotography
« Reply #16 on: January 03, 2014, 03:27:51 PM »
Reprocessed a few times with DeepSkyStacker. Tweaking the final result is a real PITA, but when you figure out how to do it right, the results are much better:



I dunno if my experience is relevant, but I held out for as long as I could before I got a tracking mount. You can do good stuff with short exposures if you go through the proper motions of dark and flat frames, and stacking a lot. Dark skies/astro filters probably make the most difference beyond that. I do all my aligning and stacking by hand in Gimp (I'm not sure any of the good free astro stack/align software is available for Macs, but anyhow that's what I'm used to now). Having said that, a tracking mount can push things further than anything.


You can extract a certain degree of quality from non-tracked stacking, but there is a limit. With short exposures, you have a very low signal strength. While you can improve SNR with stacking, you can't improve the actual image signal strength beyond a certain point, so you can never get the nice fine detail that a long exposure gets you. I've spent about two months now trying...and the shot above is about as good as I think I'll be able to do without tracking (or exceptionally dark skies, which are really rare and hard to find.)

I have done a fair amount of manual stacking in Photoshop, and the results can be quite good. Stacking software, especially the more complicated versions like DSS, Nebulosity, etc. are much more capable, but they have a high learning curve, and often their toolsets are difficult to use. I have avoided DSS up till now, but I just spent the bulk of the day working on the shot above, and I think I finally have it figured out. It's a bit noisy (it got much too cold last night, and I packed it in before I took dark frames and bias frames), but that can easily be delt with.

Exposure times of tens of seconds up to minutes can be transformative.


Indeed! I can't wait to get my hands on the Celestron EdgeHD 11" CGEM DX. I had my eyes on a 5D III for my next photography, but I think I'm going to move the telescope to the top of my list. I am curious to see how the 7D II turns out, and for astrophotography, no DSLR will really do what I want, so I'm planning on getting a monochrome CCD with the biggest pixels I can find (probably around 9µm to 9.5µm, or perhaps 5µm with the option to 2x2 bin) an dual-stage peltier cooling (which gets you up to around 77% Q.E.) I'll then be able to filter Ha, Hb, Luma, R, G, B, and any other bands independently, and blend them in post for very high detailed, full-color wide band images.

It's -33C here tonight.... I'm not terribly worried about peltier cooling :)

I have an 8" Celestron with a tracking mount.... I have tried the 60D on it, but there is WAY to much noise... My friend's 5D2 work's much better, but it is an hour's drive away and that rules it out most of the time...


If you have a tracking mount, you should be able to do worlds better than I can with the 60D. You could expose for minutes, which would create a very strong signal. You could then stack, and median averaging or something like Kappa-Sigma clipping in DSS would clean up the noise right away. I think your selling your 60D a bit short. My shots are about as good as I can do with a 7D right now because I lack a tracking mount...if I had one, I guarantee you I'd be making MUCH better shots.

There is no question that a FF sensor would do better, but the problem with the 7D (or any Canon 18mp APS-C body) with non-tracked shots is the fact that they have pitifully low signal and crappy read noise. If you can make the signal strength 100 - 1000 times more powerful, then even Canon's 18mp APS-C bodies will do very well (I've seen a lot of exceptional astrophotography from the lowly rebel series when they are used on tracking mounts.) You should give your 60D another try, and do something like 30x10 minute exposures (five full hours of tracked exposure)...I would bet the results would blow anything I've posted here WAY out of the water.


I have been thinking of getting one of these.... http://focusscientific.com/osCommerce/catalog/product_info.php/cPath/94_47/products_id/649
or
http://focusscientific.com/osCommerce/catalog/product_info.php/cPath/94_47/products_id/650


For a first astrophotography camera, I suspect I'll get the Celestron Nightscape CCD. I've seen some truly amazing images made from it, and it isn't too terribly pricey (around $1500 most of the time.)

The cameras I really want in the long run, though, are these beauties:

QHY11 FF Monochrome

Full frame, 11mp, huge 9µm pixels, monochrome, FWC ~= 6D or 5D III (around 60ke-) with Kodak CCD, read noise ~13e-.

QHY23 Monochrome

APS-C, 9mp, small 3.69µm pixels, supports 2x2 and 4x4 binning (7.38µm and 14.76µm effective pixel sizes), highest Q.E. on the market for an astro CCD @ 77% (visible green, 60% Ha & 70% Violet/Ultraviolet), FWC ~= 7D/60D/Canon 18mp APS-C (around 20ke-) with Sony CCD, read noise ~5e-.

I figure I would want both, depending on the thing I am imaging and how finely I want to delineate detail. Probably years away from getting either...the FF one is $4000, and the cropped one is $3000. :P I am sure the Celestron Nightscape will do in the interim. The one thing that seems strange to me is the readout rate of most CCD astro cameras. The often list the readout rate at Xmegapixels per second, and usually that X is significantly lower than the total megapixels on the sensor. So, for an 11mp sensor with a 1mp/s readout rate, it would take a full 11 seconds to read out the whole sensor. For the 9mp sensor, it would take over 7 seconds to read out the whole sensor. I suspect that has to do with maintaining low read noise...but it was still surprising.
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scyrene

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Re: Deep Sky Astrophotography
« Reply #17 on: January 04, 2014, 08:29:03 AM »
No doubt non-tracked stacks can't compete, but it depends what your hoping for. I was coming from non-tracked single shots, and every step forward was enough to encourage me further.

I've gone down a different route. I got a telescope, but found it unwieldy and counterintuitive. So now I have a small tracking mount designed for cameras, and the telescope is gathering dust. The downsides are inability to dial in locations in the sky (so I basically have to use trial and error for objects fainter than I can see), and an upper limit to exposure time (it's not as stable or accurate as a good tracking telescope mount, but it's enough for now and a lot cheaper).

I found, aside from tracking, the biggest improvements were made by adding an astronomical filter (I currently use a UHC filter that clips into the camera body - Astronomik do a range, APS-C only), and using wider aperture lenses. Although shooting wide open adds some optical problems, the extra light gathering at f/1.2 versus f/2.8 is stunning for the night sky.

The biggest problem is still the weather! Cloud-free, low wind nights below the dew point are rare indeed in these parts.
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weixing

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Re: Deep Sky Astrophotography
« Reply #18 on: January 04, 2014, 09:58:13 AM »
Hi,
    It's a long time since I last do some Astrophotography due to the unpredictable weather...  :(

I found, aside from tracking, the biggest improvements were made by adding an astronomical filter (I currently use a UHC filter that clips into the camera body - Astronomik do a range, APS-C only), and using wider aperture lenses. Although shooting wide open adds some optical problems, the extra light gathering at f/1.2 versus f/2.8 is stunning for the night sky.
    Any problem when you use those fast lens with the Astronomik filters?? I thought they are design for f3.8 to f15...

    By the way, now they have clip on filters for Canon 5D and 6D full frame camera, but I think you had to lock the mirror in up position to install the filters, so might not be that useful if you need the viewfinder to aim.

    Have a nice day.

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Re: Deep Sky Astrophotography
« Reply #19 on: January 04, 2014, 12:46:33 PM »
    Any problem when you use those fast lens with the Astronomik filters?? I thought they are design for f3.8 to f15...

    By the way, now they have clip on filters for Canon 5D and 6D full frame camera, but I think you had to lock the mirror in up position to install the filters, so might not be that useful if you need the viewfinder to aim.

Is that right? I'll have to see - using the 5DIII would improve things a lot. One thing that's relevant in any case is the Astronomik EOS clip filters (for 1.6 crop bodies) actually fit into the super telephoto lens rear filter holder (on my 500 II at least). Sadly my tracking mount can't handle the weight of that lens and body combination, so I've never made much use of it - but it's worth knowing.

As for aperture, I suspect it's the reason I get a lot of halos around stars. They are, as you say, rated for medium to narrow apertures (by lens standards). With the UHC filter, many stars get bright magenta halos, which can be a pain to remove if your main subject is a red/pink nebula. Nonetheless, other than that, I've found no problems, and a tradeoff worth making in my experience.
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Re: Deep Sky Astrophotography
« Reply #20 on: January 04, 2014, 12:58:33 PM »
I had a chat with Astronomik in the past about their narrowband filters and fast lenses. I think the e-mails are on my work account so I can't find it right now. Although their website rates them as usable from f/2.8, they said f/2.0 was ok. Any benefit from going even faster will reduce.

I did a lot of my early attempts with the 135L wide open. Note the lens is rather horrible for wideband imaging as the red focus is some way off that of green/blue. It is fine for narrowband.

If you go for only light pollution filters like the CLS, that should be less affected by extreme speed but I haven't tried it.

And finally, I didn't realised they did full frame clip filters now! Shall have to have a look. Requiring mirror lock up isn't a big deal. People like using USB connection to help with focusing so you see what the sensor sees. My biggest problem now is, do I really want to modify my 5D2?... probaby not, I've not gathered a single night sky photon this winter. Must stop being lazy! Not a great hobby if you don't like the cold.

Edit: here's one of my early attempts at Andromeda galaxy with the 135L at f/2, CLS filter on 600D (unmodified). 100% crop, processed. I have got a bit better since then... :)

« Last Edit: January 04, 2014, 01:06:54 PM by lol »
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Quasimodo

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Re: Deep Sky Astrophotography
« Reply #21 on: January 04, 2014, 02:11:48 PM »
This is imho the most inspirational thread I have read in this forum for quite a while!

I have never tried astrophoto myself (except when I was lucky to borrow the 800/5.6 with a 2xIII TC to take picture of the moon, but that would hardly count as the moon is very bright so the exposure time is very short).

I have been reading this whole thread on my ipad retina, and it has quite good resolution. However, due to the restrictions on image size here in CR, I would have loved to see full resolution images of your beautiful pictures if you guys have posted them somewhere else? :)
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Re: Deep Sky Astrophotography
« Reply #21 on: January 04, 2014, 02:11:48 PM »

scyrene

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Re: Deep Sky Astrophotography
« Reply #22 on: January 04, 2014, 03:33:56 PM »
Edit: here's one of my early attempts at Andromeda galaxy with the 135L at f/2, CLS filter on 600D (unmodified). 100% crop, processed. I have got a bit better since then... :)




I'd have been very happy with that! Andromeda is a target I've struggled with. Partly because it's hard to locate (no very bright nearby stars) and partly my filter seems to bring out hydrogen emission nebulae much better than galaxies or reflection nebulae (e.g. the Pleiades).

Incidentally, the 135L is a lens I've considered as my next step for this work. Would you recommend it? The 100L macro has done pretty good service so far, but I'd love more reach (and as I say, the 500L II is too heavy for my tracking mount).
5D mark III, 50D, 300D, EOS-M; Samyang 14mm f/2.8, 24-105L, MP-E, 85L II, 100L macro, 500L IS II, EF-M 18-55; 1.4xIII, 2x III + 2xII extenders; 600EX-RT; EF-M--EF adaptor.
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lion rock

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Re: Deep Sky Astrophotography
« Reply #23 on: January 04, 2014, 06:00:20 PM »
LOL,
What a fantastic image, I would think it came out of KECK in Hawaii!
Hats off to you.  Please show more, with a bit of instructions to the rest of us!
Thanks.
-r

jrista

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Re: Deep Sky Astrophotography
« Reply #24 on: January 04, 2014, 07:27:35 PM »
    Any problem when you use those fast lens with the Astronomik filters?? I thought they are design for f3.8 to f15...

    By the way, now they have clip on filters for Canon 5D and 6D full frame camera, but I think you had to lock the mirror in up position to install the filters, so might not be that useful if you need the viewfinder to aim.


Is that right? I'll have to see - using the 5DIII would improve things a lot. One thing that's relevant in any case is the Astronomik EOS clip filters (for 1.6 crop bodies) actually fit into the super telephoto lens rear filter holder (on my 500 II at least). Sadly my tracking mount can't handle the weight of that lens and body combination, so I've never made much use of it - but it's worth knowing.

As for aperture, I suspect it's the reason I get a lot of halos around stars. They are, as you say, rated for medium to narrow apertures (by lens standards). With the UHC filter, many stars get bright magenta halos, which can be a pain to remove if your main subject is a red/pink nebula. Nonetheless, other than that, I've found no problems, and a tradeoff worth making in my experience.


Hmm! I'll have to check out Astronomik's filters for the supertelephoto lenses. I have the 600/4 L II, which is basically like a good Apochromatic refractor. I have my eye on the Celestron CGEM DX mount, which is about $1200 alone, and it should be able to hold my lens and camera quite easily. Having a light pollution filter would make it a lot easier for me to do some deep sky astrophotography without having to find time to drive an hour or so out of town to find clean dark skies. Thanks for the tip!

Edit: here's one of my early attempts at Andromeda galaxy with the 135L at f/2, CLS filter on 600D (unmodified). 100% crop, processed. I have got a bit better since then... :)




I'd have been very happy with that! Andromeda is a target I've struggled with. Partly because it's hard to locate (no very bright nearby stars) and partly my filter seems to bring out hydrogen emission nebulae much better than galaxies or reflection nebulae (e.g. the Pleiades).

Incidentally, the 135L is a lens I've considered as my next step for this work. Would you recommend it? The 100L macro has done pretty good service so far, but I'd love more reach (and as I say, the 500L II is too heavy for my tracking mount).


Ditto! I'd have been happy with that, too! That is really quite good for just the 135L. I guess I would have gone with a different white balance, but that is a pretty darn nice photo! Out of curiosity...did you use a tracking mount? Signal strength looks pretty good in that shot...a hell of a lot better than I've ever been able to get with my 100mm f/2.8. Stars are nice and round, too...something I've never been able to get without tracking.
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jrista

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Re: Deep Sky Astrophotography
« Reply #25 on: January 04, 2014, 07:30:36 PM »
This is imho the most inspirational thread I have read in this forum for quite a while!

I have never tried astrophoto myself (except when I was lucky to borrow the 800/5.6 with a 2xIII TC to take picture of the moon, but that would hardly count as the moon is very bright so the exposure time is very short).

I have been reading this whole thread on my ipad retina, and it has quite good resolution. However, due to the restrictions on image size here in CR, I would have loved to see full resolution images of your beautiful pictures if you guys have posted them somewhere else? :)


Glad your finding it inspirational! :) I find the sky to be quite inspiring in and of itself. :D

Regarding larger resolution images, personally, I don't have anything really high resolution. You can find all my work at jonrista.com, and the images there will be a little higher resolution. I downsample them all right now to reduce noise (at full size, they really don't look all that good.) Once I am able to get a tracking mount, I hope to produce MUCH larger and more detailed images, and I'll happily share them. Not sure when that will be, though...few months away at least, if not the end of the year.
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jrista

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Re: Deep Sky Astrophotography
« Reply #26 on: January 04, 2014, 07:33:18 PM »
While out at my dark skies site the other day, I also managed to get some wider field milky way shots. I think you can even see some airglow in these photos (the green and red haze in the bottom half):





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scyrene

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Re: Deep Sky Astrophotography
« Reply #27 on: January 04, 2014, 10:37:57 PM »
Hmm! I'll have to check out Astronomik's filters for the supertelephoto lenses. I have the 600/4 L II, which is basically like a good Apochromatic refractor. I have my eye on the Celestron CGEM DX mount, which is about $1200 alone, and it should be able to hold my lens and camera quite easily. Having a light pollution filter would make it a lot easier for me to do some deep sky astrophotography without having to find time to drive an hour or so out of town to find clean dark skies. Thanks for the tip!

Ditto! I'd have been happy with that, too! That is really quite good for just the 135L. I guess I would have gone with a different white balance, but that is a pretty darn nice photo! Out of curiosity...did you use a tracking mount? Signal strength looks pretty good in that shot...a hell of a lot better than I've ever been able to get with my 100mm f/2.8. Stars are nice and round, too...something I've never been able to get without tracking.

I've posted a couple of pics here to show how it works. The filters are almost exactly the same size as the glass window in the filter holder, so you just balance/wedge it in there. It can fall out (into the lens!) so you have to be careful, although it can be retrieved with difficulty.

I've also included my best shot so far, since others are including photos. It's the North America Nebula with the 50D, UHC clip filter, and 100L macro + Kenko 2x teleconverter. Magic Lantern for bulb time lapse, which automates the capture process once it's aligned. Hand stacked and processed in Gimp, finished in Lightroom. 136x1mins at ISO 6400.

On the subject of star shape, the clip filter deforms bright stars to the shape of its opening - roughly a circle with the top and bottom cut off - at least shooting at wider apertures. And the coloured haloes only appear around medium-brightness stars, not the faintest, nor the very brightest. Not quite sure why.
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Re: Deep Sky Astrophotography
« Reply #27 on: January 04, 2014, 10:37:57 PM »

Don Haines

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Re: Deep Sky Astrophotography
« Reply #28 on: January 04, 2014, 10:58:48 PM »
Still playing and learning......
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Re: Deep Sky Astrophotography
« Reply #29 on: January 04, 2014, 11:17:34 PM »
I've used various astro software over the years, but I think only once or twice did I manually stack images.  I do all my stacking with DeepSkyStacker - free and quick to learn.  The resulting 16 bit tiff is opened in Adobe Camera Raw, tweaked and sent to Photoshop for final work.  I typically take 90 second exposures but sometimes shorter exposures for brighter objects like globulars and planetary nebulae.  I've been off work for two weeks and had ONE night suitable for any kind of astro work, and not very well suited at that, upper atmosphere turbulence was horrible and I was doing some imaging of Jupiter.  Comparing the use of a modified webcam to the crop video with a 60D for a Registax presentation with my local astronomy club next week.  I use a 60D, an astro modified 40D and once the weather clears I'll be using a 6D.  I have assorted clip filters for the 40D, they allow me to image from my light-polluted back yard.  The 40D is somewhat noisy and prone to banding, but the trade off is Ha sensitivity.  I gotta believe a modified 6D would be exquisite for astro.

I would love to have a cooled CCD imager, but it's difficult to justify to myself, let alone SWMBO.  Our observing season in the FL Panhandle is just too short, and the CCD would be suitable for ONLY astronomy, unlike a DSLR.

Without tracking, I only shoot wide field or time lapse.  I've got two CG5 GOTO mounts, one carries a C8 and the other a small refractor with a piggybacked camera/telephoto combo.  I've a non-GOTO fork-mounted C9.25 that tracks phenomenally well....but that scope seems to get 5lbs heavier every year.  (I realize this isn't a 'for sale' site, but if anyone with a younger/stronger back is visiting NW Florida and interested yer welcome to come take a look.)

Here's an assortment of images, the Trapezium with un-modified 40D (C9.25 with 2XTC), M51 with un-modified 60D (C8 with f/6.3 focal reducer) and the rest with a modified 40D (300mm/4L or 4 inch f/5 refractor).

Other such stuff is at    pbase(dot)com/emagowan/astrophotography

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Re: Deep Sky Astrophotography
« Reply #29 on: January 04, 2014, 11:17:34 PM »