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Old 22-01-2012, 06:23 AM
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CapturingTheNight (Greg)
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Canon 60D Purple Star Colour

Hello All,
Been pulling my hair out on this one for a while now. I have two DSLR cameras that I use for astrophotography. A 1000D that I use prime focus on the telescope and a 60D that I use for terrestrial photography and I occasionally piggyback to the scope for widefields. The 60D is fine for 30 second fixed tripod astrophotos but whenever it gets a ride on the back of the scope for 2-10 minute exposures I always seem to get purple/blue stars and/or coma. My problem solving with this has been extensive. First tried just adjusting the white balance of the RAW shots in post. Can't tune it out. Then tried removing UV protection filters from lenses. No difference. Tried different lenses (I have 6- 3 Canon and 3 Third Party). Happens with all lenses. Tried different aperture settings. Still happens.
Yet, I put the 1000D on the same target with the same lens with exactly the same camera settings and the stars are perfect.
Is there something I am missing with the 60D? From my experiments I am convinced it has to be the camera itself and not an issue with any lens.
Or at the very least is there a way I can tune this out in Photoshop. I have tried everything I can think off in Photoshop but I don't pretend to be an image processing expert. Please
I have attached a sample image of what I am talking about.
I will inevitably ditch the 60D in the future and go full frame with something like the 5D Mark II but until that time when funds are slightly more plentyful I have to work with the 60D.
Thanks
Greg
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Old 22-01-2012, 09:25 AM
adman (Adam)
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How are you focusing?

even triplets will give you fringing just outside of proper focus.

Adam
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Old 22-01-2012, 11:16 AM
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CapturingTheNight (Greg)
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Quote:
Originally Posted by adman View Post
How are you focusing?

even triplets will give you fringing just outside of proper focus.

Adam
Hi Adam. Focusing using magnified live view, but I'm not really concerned about the fringing I am getting. It's the colour of that fringing that bothers me. I just don't get it with the 1000D. I don't think that my focus would be spot on whenever I use the 1000D and out whenever I use the 60D.
Cheers
Greg
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