EOS Rebel T3: How to take night sky photos

[Styner]

Hi. I am beginner photographer and was wondering how do I take night sky photography with a EOS Rebel T3. Zoom lens of 300mm

[stevet1]

Styner,

I don't do night-sky photography myself, but this is what I have read:

1) Use as wide an Aperture as you can for light-gathering abilities. Some recommend an aperture of around f/2.8

2) Try to take long exposures, but don't go over 25 seconds, as the stars begin to blur because of the earth's rotation, and you begin to get star trails. There is a 500 rule. Divide 500 by your focal length. For a 20mm lens, 500÷20=25 seconds. Use as minimum focal length as you can to get big skies.

3) Use an ISO anywhere between 400 on up to 1600, or even 3200. If you are in an area of high light pollution, you'll use the lower ISO's.

At least that's what I've read.

Steve Thomas

[Waddizzle]

“500 Rule”

You need to compensate for the crop factor with an APS-C camera.  I usually advise people to multiply by 2, instead of 1.5 or 1.6, to keep the math simple and manufacturer independent.  Besides, multiplying by 2 works for MFT sensors, too.