Stars and a tiny Andromeda

freefall

freefall

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Went out last night and snapped a few of the sky. I used an 85mm and a tripod with the mirror locked up. The mirror lock up was great at the start of the shot when the timer ran out but I could hear it slapping the 5d's insides when the shot finished.

My main issue was focus. I manually focused on the brighest star using liveview as af could not pick it up. I did try a few with focus on the moon then switch it to manual (but leave it) then have a go at the stars.

Any advise greatly received (y)

023_365.jpg
 
Oh I forgot to say this is already a crop of about 1/3 of the total image. Basically it was a landscape photo turned into portrait. 21mp of canon 5dmkII.
 
You can either set your lens to infinity if it is marked up, or as you say zoom in on live view to the brightest star and try to gently adjust your focus ring. Don't forget a narrower F number would help a bit.

The more you crop on these types of shots the more you will see blur.
Good effort!

Kris
 
Mirror lock-up has negligible effect on the final image above shutter speeds of about 5 maybe 10 seconds, the vibrations of the mirror action only last briefly and are only really needed for shutter speeds of approximately 1 sec to 1/50th sec. The numbers may differ slightly between photography sites/photographers but are essentially the same ball park.
You're just as likely to have as much blur from the lightest of winds if you're using anything above 100mm focal length.
I pretty sure a lot of togs will disagree but the proof is in the pudding, at shutter speeds above 5 or 10 secs, you won't see any difference.
 
I used to use mirror lockup on astro shots, but with exposures over 2 to 3 minutes in length, I don't bother any more. I also don't think you'll get any motion caused by the dropping of the mirror back into place at the end of the shot, as I understand it, the shutter has already closed at that point.

Focus is critical, and do your best...I've heard of using a Y mask to achieve focus, and keep meaning to make one, but haven't got around to it yet. However, at 50mm I've not noticed any real issues... more problems at 200mm though. As for stopping down... unless you get major issues with the edges (50mm f/1.8 needs to be about f/4, the 50mm f/1.4 is ok at f/3.2), don't. You need to let in as much light as possible.

the stars look ok in that, and there's some nice width to Andromeda. You don't say, so I'm gonna guess this is a single shot, in which case, you have pretty good skies. If it is a single shot, then capture at least 10 or 20 and stack them with something like Deep Sky Stacker. (don't forget darks, cap the lens, and shoot another 5 to 10, and load into DSS as ... well darks ;)) Then comes the fun part of processing...

This might help

http://www.talkphotography.co.uk/forums/showthread.php?p=1184389#post1184389
 
jgs001 said:
I used to use mirror lockup on astro shots, but with exposures over 2 to 3 minutes in length, I don't bother any more. I also don't think you'll get any motion caused by the dropping of the mirror back into place at the end of the shot, as I understand it, the shutter has already closed at that point.

Focus is critical, and do your best...I've heard of using a Y mask to achieve focus, and keep meaning to make one, but haven't got around to it yet. However, at 50mm I've not noticed any real issues... more problems at 200mm though. As for stopping down... unless you get major issues with the edges (50mm f/1.8 needs to be about f/4, the 50mm f/1.4 is ok at f/3.2), don't. You need to let in as much light as possible.

the stars look ok in that, and there's some nice width to Andromeda. You don't say, so I'm gonna guess this is a single shot, in which case, you have pretty good skies. If it is a single shot, then capture at least 10 or 20 and stack them with something like Deep Sky Stacker. (don't forget darks, cap the lens, and shoot another 5 to 10, and load into DSS as ... well darks ;)) Then comes the fun part of processing...

This might help

http://www.talkphotography.co.uk/forums/showthread.php?p=1184389#post1184389
Click to expand...

thanks very much for all the replies and especially that "bookmarked" link! (y)

Yeah it was a single shot on 85mm. Think it was f4 and iso6400. I got about a 4 second exposure if I remember rightly and had to drop the blacks back to sort it out. It still looks colour noisy to me. I will read and re read that thread of yours. Thanks so much! :clap:
 
Your welcome. Stacking a large number of shots will increase the SNR, so the shot will appear to become less noisy. At 4 seconds, you can probably stack some 40 to 50 shots, possibly more, without getting field rotation effects smearing the stars at the edges. Watch out for LP (light pollution) though, it sounds like you may have been affected by it.
 
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