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Old 30th of September 2013 (Mon)   #1
tkbslc
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Default Can I do star shots with any of my lenses?

I live in a city with bad air and too much light pollution so I've never really tried to do any night landscapes with star shots. But I'm visiting family in Southern Utah soon and wanted to try some. Ive got my gear list in my signature, can I do these kinds of shots with what I have? 15mm f3.5 bright enough? Should I use my 22mm f2 on the EOS M instead?

I'm assuming wide aperture and medium ISO?
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Old 1st of October 2013 (Tue)   #2
spotz04
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Default Re: Can I do star shots with any of my lenses?

Faster lenses are ALWAYS better for night sky pics so try some with your 22mm and your 30mm.

However, while playing around I tried using my 17-40 for the milky way near the Moab desert (pic below). Dark sky area far enough away from any towns. 5DII, 17mm, f/4, 39 sec, ISO 6400, so it is doable with a slower lens. Just be prepared for lots of noise clean up when using higher ISOs.

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Old 1st of October 2013 (Tue)   #3
the jimmy
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Default Re: Can I do star shots with any of my lenses?

One thing to remember is with any lens shooting stars, you can only expose for so long before the rotation of the earth becomes apparent. When that happens you'll get star trails, IOW in your photo the stars start to elongate. The only way to avoid this is to have a tracking mount, which I'll assume you don't have. However you can still get very good results with just your camera and a sturdy tripod. For examples you may want to look thru this thread. Good luck and post back in the Astronomy and Celestial photo sharing section

There is a way to find out how long you can expose with a given focal length before you'll see star trails form, this formula will cover full frame and 1.6 crop bodies.
divide 600 by the focal length of the lens = maximum number of seconds before star trails form, for a full frame camera body.
For a crop body first convert the lens to the full frame equivalent; ex. 14mm lens x 1.6 = 22.4mm
600 / 22.4 = 26 seconds
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Old 1st of October 2013 (Tue)   #4
tkbslc
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Default Re: Can I do star shots with any of my lenses?

Thanks for the math above. I'll give it a try.

Suppose I wanted to try one with star trails, how long do you need to expose for a noticeable rotation
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Old 2nd of October 2013 (Wed)   #5
spotz04
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Default Re: Can I do star shots with any of my lenses?

Most do star trails in multiple short exposures, as opposed to one long exposure, and then stack the pics. Use startrails.exe.

http://startrails.de/

Also, take some dark frames, same shots but with your lens cap on -- helps to eliminate all the hot pixels that will be created from your long exposures. Use these in the stacking process, shot right after you do your light (star pics) frames.

Last edited by spotz04 : 2nd of October 2013 (Wed) at 06:55.
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Old 4th of October 2013 (Fri)   #6
topdslrs
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Default Re: Can I do star shots with any of my lenses?

Quote:
Originally Posted by the jimmy View Post
One thing to remember is with any lens shooting stars, you can only expose for so long before the rotation of the earth becomes apparent. When that happens you'll get star trails, IOW in your photo the stars start to elongate. The only way to avoid this is to have a tracking mount, which I'll assume you don't have. However you can still get very good results with just your camera and a sturdy tripod. For examples you may want to look thru this thread. Good luck and post back in the Astronomy and Celestial photo sharing section

There is a way to find out how long you can expose with a given focal length before you'll see star trails form, this formula will cover full frame and 1.6 crop bodies.
divide 600 by the focal length of the lens = maximum number of seconds before star trails form, for a full frame camera body.
For a crop body first convert the lens to the full frame equivalent; ex. 14mm lens x 1.6 = 22.4mm
600 / 22.4 = 26 seconds
I'd like to add that the earth's rotation is more pronounced and apparent in photos at lower latitudes.
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