I took night time pictures of a church against a starlit sky with my 5D a few nights ago. This was the first time I used the 5D for night time sky images.

To my surprise what were bright white stars in reality appear as red, blue and white spots in the sky.

What caused this and how do I prevent it in the future.

Camera was 5D with 50/1.4 lens.

Sounds like red/cyan ca.

Edit: That applies only if each star is red-white-cyan (or the reverse). Otherwise it could be hot pixels.

What are you doing for white balance? You could experiment with custom settings, or you could put a gray or white card in the frame and balance using that if you shoot RAW.

If that doesn't help you could also evaluate your exposure, as the dark sky could cause you to overexpose the stars, which then could produce "fringing" at the high contrast edges. Look at the discolored stars at 100% or more magnification and see if the centers are blown out and the edges ringed by red, etc.

Some stars do burn in different colours which may not be visable to the naked eye but come through on long exposures (or when magnified greatly). Otherwise it's probably hot pixels, are they in the same place on each exposure?

There's no problem with your camera. Stars are suns, or rather our sun is a star, and there are red dwarfs, huge gas giants... many different types of stars. As was mentioned, to our eye they appear to be all 'white', but on film or in this case a digital sensor, their 'true colours come shining through'.

Mike.

Neato. I've never had any show up other than white. I'll have to play some more.

Here are two sample images. The first one was taken handheld (hence the jitters) showing Mars and several stars in a horizontal 'candy cane' shape. The second one is the Big Dipper. Both show white, blue, red, yellow...

Mike.

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