Night sky pics – tips wanted

[kashari]

I was up in Cottonwood AZ for a few days and the night skies are awesome up there. I was going to try my first star trails type of thing, but couldn’t get my D60 to fire. It’s probably something really stupid that I was missing, as I usually try to make things more difficult than they should be. I have a remote and was going to do the Time/Bulb exposure, but kept getting an error message saying it was too dark. IIRC, I was in manual mode. I looked up all sorts of tips about shooting the stars but didn’t see this addressed, so that’s why I think I was being a dork and missing the obvious. Any ideas?

[orionid]

Did you have it in manual focus, too?

[kashari]

Did you have it in manual focus, too?

Yeah, I’m pretty sure I tried that and I tried to focus on the brightest star.

[chupathingie]

Unrelated, but this reminded of Bahtinov Masks…
http://en.wikipedia.org/wiki/Bahtinov_mask
very useful for getting accurate focus. Focus on stars is a lot harder than some might think… and soft focus really kills astro images.

[ravnostic]

Unrelated, but this reminded of Bahtinov Masks…
http://en.wikipedia.org/wiki/Bahtinov_mask
very useful for getting accurate focus. Focus on stars is a lot harder than some might think… and soft focus really kills astro images.

…and you wouldn’t believe how hard it was to find this information when I needed it, without remembering ‘Bahtinov’.

//saved the PDF versions. Will be building this weekend, for an upcoming astrophotographic safari. Thanks, Chupa!

[Farktographer]

Got myself an ML-L3 yesterday so I could finally do bulb shots. I was hoping to get some streaking if I telescoped in a bit, since we can’t stack for the upcoming contest. I set up my tripod and left the exposure open for 30 minutes with f/13. What I got was the horrible mess below:

Any thoughts? I’m thinking that my aperture was too large, but even then, there’s not a discernible star in the sky. Too much light pollution? I’m thinking of making another attempt near the beach where there’s not so much city interference. I don’t even know if people can get streaking goodness without stacking images – just going out on a limb here, hoping I can.

[lokisbong]

Got myself an ML-L3 yesterday so I could finally do bulb shots. I was hoping to get some streaking if I telescoped in a bit, since we can’t stack for the upcoming contest. I set up my tripod and left the exposure open for 30 minutes with f/13. What I got was the horrible mess below:

Any thoughts? I’m thinking that my aperture was too large, but even then, there’s not a discernible star in the sky. Too much light pollution? I’m thinking of making another attempt near the beach where there’s not so much city interference. I don’t even know if people can get streaking goodness without stacking images – just going out on a limb here, hoping I can.

I get pretty good str trail pictures with no stacking as long as there is no moisture in the air. I think you have a bit of humidity going on with way to much light pollution.

1-10-2011 by lokisbong, on Flickr
this is 6 and a half minutes no stacking

[Farktographer]

I get pretty good str trail pictures with no stacking as long as there is no moisture in the air. I think you have a bit of humidity going on with way to much light pollution.

1-10-2011 by lokisbong, on Flickr
this is 6 and a half minutes no stacking

Thanks for the tip. I was able to get some tails on 10-minute exposures when I gave it a shot tonight. I went a bit further from light pollution and made sure to aim for places with no cloud cover whatsoever. Could be better, but I’m not going to be getting out of the city before this week’s submissions – this will be useful in the future though.

[chupathingie]

I managed some trails from within DFWs horrid light pollution by using shorter subs and stacking (short of an LP filter it’s the most viable weapon against LP). Shoot in RAW, blur the sub and subtract the blurred image from the original. This will drop most of the LP, and stretching the levels selectively will bring the stars out. This MUST be done in 16bit/channel, since in most cases you’ll be setting black point, stretching, and repeating (this kills an 8-bit image very quickly). This will work for a single image, but a long exposure under LP skies will usually saturate the red channel. I normally take a sample shot and try to keep the histogram from creeping up into the top third. Multiple exposures and stacking is almost a must, since the long exposures will generate a lot of thermal noise that becomes even more evident when you start to stretch levels.

If you’re using PS, there are a few noise-handling plugins available (Noise Ninja comes to mind) that I’ve seen used to great affect. PS and the plugins are something I miss from back before I went FOSS on the home PC. 🙁

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