Constellation Photography

eric-holmes

No longer a newbie, moving up!
Joined
Aug 8, 2009
Messages
1,858
Reaction score
49
Location
Arkansas
Can others edit my Photos
Photos OK to edit
I was hoping to get some tips on how to shoot a constellation. I do not want to capture star movement. Just the actual constellation itself.

My personal understanding of photography leads me to think this:

-wide open apeture to allow more light in
-not too long of a shutter speed to prevent trails (<10 sec?)
-I don't know about the ISO. I would guess low to prevent noise but higher would allow more light for a quicker shutter speed.

I have two lenses. A 50 1.8 and a 18-105 3.5-5. Which would you suggest using? Thanks for any help.
 
I'd also like to hear some information on this. Though my understanding is that you generally need a really high ISO, otherwise shutter speeds become too long and star trails result. I woudl also guess the same about a wide open aperture hence I'd say the 50mm would be your best bet if it is wide enough, though it may prove to be more valuable to sharpen the lesn up by stiopping down to f/2.5 or so.

I saw a shot my friend took on his 5dmk2 of a nightime landscape out in the country with a beautiful night sky, it was very cool. Not sure what ISO he used, but the 5d2 (or nikon equaivalent) would probably be the weapon of choice for many people.
 
A motor driven equitorial camera mount that can counter act the Earth's rotation is very handy for exposures of up to 45 seconds at low ISO's, as is very dark skies with little light pollution.

Many photographers just mount their camera piggyback on their motor driven telescope.
 
You have two things working against you. First off, Orion is setting very early these days and won't be visible again for around 3-4 months (very early in the morning). I know you didn't mention that here, but you did in your other thread.

The second thing is that you need a way to compensate for Earth's rotation. This is easiest done with a mount that tracks the sky (passively). These can be cheap to expensive and effective to very ineffective.

Alternatively, you would need software that will auto-align to fractional degree rotations. In other words, you would be taking many shorter exposures and using software to stack them together. Because Earth rotates, you would need to apply fractional rotations to each image. I'm sure there's software out there that'll do it automatically, but since I have access to proper mounts, I don't know of them off-hand.

If you're using a proper mount, then longer exposures at your sharpest f/stop (usually f/8ish) at low ISO is what you want. You would still want to do 3 or 5 shots or so and average them together to increase the signal-to-noise ratio (S/N).

If you're doing the regular tripod without a tracking mount, then you can get away (and are required) to do numerous shorter exposures at higher ISO. Check this post for why you can get away with a higher ISO. The length of your exposure in that case is a simple function (well, complicated function) of the focal length and sensor size of your camera and lens. You can do a simple test shot for 30 sec and see what the trails look like, halve it, see what happens, and narrow it from there.
 

Most reactions

Back
Top