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how far can you go using a photography kit for astrophotography?

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#1 ma_khan

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Posted 05 March 2021 - 11:37 AM

orion_nebula.jpg

 

I am a beginner and currently working on my next steps. Took the above image yesterday from bortle 9 skies using iOptron sky tracker, canon EOS 6D markii and canon 70-200 f/2.8.

 

111 frames, each with 20s f/4 ISO 1600. Stacked with DSS and processed in Photoshop. No Filters. 

 

I am trying to understand what the reach is with the equipment I am working with. I had disappointing results shooting farther\fainter objects and that's understandable. 

 

I am looking for feedback on the image and what you can observe both in terms of processing and acquisition. I am also looking for targets you think my equipment will be able to handle. I was thinking pleiades? Anything else that might work?



#2 randcpoll

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Posted 05 March 2021 - 12:06 PM

It depends on how good a polar alignment you can get with your star tracker. I use the Skywatcher Star Adventurer and can go 2 minutes with a 300mm lens. With your 6D ii those exposures will expand your capabilities to most of the brighter deep sky objects and to nearly all but the smallest/faintest of star clusters and galaxies.



#3 ma_khan

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Posted 05 March 2021 - 12:12 PM

Thanks! That gives me hope. I am able to go longer, but I haven't been doing so because of the amount of light pollution I have to deal with. Anything more than 30 secs and images are just whitewashed by light pollution. I haven't been able to find a clip in filter for Canon 6D Mark ii. Apparently, its difficult to make for this full frame sensor type or something like that. 



#4 Islander13

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Posted 05 March 2021 - 01:08 PM

When you say 'how far can you go...' I wonder how far that you have to go to get darker skies. The beauty of your setup (and mine) is that it is grab and go. I'm lucky to live in Bortle 4 skies, but I like the idea of being portable.

 

I'm moving up from Canon 5D2 with no tracker to just adding a Skyguider Pro, and waiting for delivery of a William Optics z61. I had sold my 70-200 f2.8 before I got into AP. So it was either re-buy an EF Telephoto or go to the short refractor. 

 

I think that your current set-up should take you a long ways - but darker skies would definitely help.



#5 Kendahl

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Posted 05 March 2021 - 05:52 PM

M42 is overexposed. I suspect this happened during processing because your subexposures were shorter than I would have used at the same ISO and focal ratio. (I have the advantage of darker skies.)

 

Your stars are round which means your guiding is adequate for your subexposure duration. If you haven't already done so, you might experiment with longer ones. Reduce ISO in proportion to keep exposure the same. Back off when you begin to see star trails.

 

If your camera tracker doesn't have a polar alignment scope, there are other ways to get a decent polar alignment. For a first approximation, use Google Maps of your observing site at highest resolution. Here is a good article that covers several methods for polar alignment: https://uncle-rods.b...alignment party. Drift  alignment is the most complicated and tedious but is the most accurate. If you always observe from the same site, try marking the positions of your tripod legs and put them back in the same place next time.

 

Your camera is excellent but your zoom lens isn't. If you look at stars in the corners of your images, I think you will see that they are far from round. The problem lies in the lens, not in your guiding. Jerry Lodriguss has this article about camera lenses for astrophotography: http://www.astropix....rop/lenses.html. It contains a list of good Canon lenses.

 

If practical, find a darker place for your astrophotography. Not having to subtract out light pollution makes a huge difference in the quality of your images and the time it takes to get enough data for a good image.



#6 DJL

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Posted 05 March 2021 - 06:16 PM

Rather than a light pollution filter, try Astro Pixel Processor and it's light pollution removal tool. 


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#7 ma_khan

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Posted 05 March 2021 - 09:27 PM

M42 is overexposed. I suspect this happened during processing because your subexposures were shorter than I would have used at the same ISO and focal ratio. (I have the advantage of darker skies.)

 

Your stars are round which means your guiding is adequate for your subexposure duration. If you haven't already done so, you might experiment with longer ones. Reduce ISO in proportion to keep exposure the same. Back off when you begin to see star trails.

 

If your camera tracker doesn't have a polar alignment scope, there are other ways to get a decent polar alignment. For a first approximation, use Google Maps of your observing site at highest resolution. Here is a good article that covers several methods for polar alignment: https://uncle-rods.b...alignment party. Drift  alignment is the most complicated and tedious but is the most accurate. If you always observe from the same site, try marking the positions of your tripod legs and put them back in the same place next time.

 

Your camera is excellent but your zoom lens isn't. If you look at stars in the corners of your images, I think you will see that they are far from round. The problem lies in the lens, not in your guiding. Jerry Lodriguss has this article about camera lenses for astrophotography: http://www.astropix....rop/lenses.html. It contains a list of good Canon lenses.

 

If practical, find a darker place for your astrophotography. Not having to subtract out light pollution makes a huge difference in the quality of your images and the time it takes to get enough data for a good image.

Thank You! This is very informative. Yes, the over exposure is in post. Here is another process I did today from the same stacked file.

 

orion_720.jpg

 

I live in Chicago which means access to any kind of dark site is at least 90 minutes away. I am going to try your suggestion of increasing the time by lowering ISO. Will report how that goes.  


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