Problem with CA 20D

[dwdallam]

I took these pictures last experimenting with the exposure to get the effect I wanted. I have read about this sort of CA, but I forget the type it is. Is tehre anything I can do to prevent this from happening?

Camera: 20D
Type: RAW
Lens: 70-200mm f2.8L
Filter: UV Haze (L-39 Sharp Cut)
Using lens hood.
Focal length was approx. 80 and around 190mm (I have other shots with the same problem).
f2.8/13 seconds (average)

The problem seems exacerbated by more over exposure.

My friend was asking about the filter, and said it might be the filter depending on its coating. If the above filter is not what I need, or could be causing the problem, please advise. I've decided to change the Cannon UV filter tomorrow at B&H for the Hoya UV, but I need to know which to buy: Hoay Super MC at 52.00 or the regular MC at 40.00? If the Super is really better, the 12.00 is no biggie.

http://www.idlethoughtsandchaos.com/photo/

[jeffreyluce]

I've noticed that my filter causes the ghosting of lights.  I just unscrew it.

[dwdallam]

I've noticed that my filter causes the ghosting of lights.  I just unscrew it.

If that is true, and you have a non coated filter, then I'll bet a MC UV would do the trick.

[Jonathan Wienke]

I'd say forget about any filter, unless you are shooting motocross or something similar where abrasive substances are being spattered on the lens. The lens hood for the 70-200 will protect the front lens element from most impact/scratch damage better than a UV filter, and will reduce flare and ghosting rather than increase it. What you're seeing has nothing to do with CA, its a type of flare caused by a filter reflecting light from the front lens elements back into the lens. Chromatic aberration is a type of color fringing where the fringe colors on opposite sides of an object are complementary (green/magenta, blue/yellow, red/cyan, etc).

[abaazov]

jonathan i have had the same problem a few times, it can really ruin a beautiful picture. are you saying not to use a filter at all? this is the first tiem i have ever heard someone say that. this problem can happen with any kind of filter? is this problem actually the same as the lens flare function in photoshop?

thanks...
amnon

[Jonathan Wienke]

are you saying not to use a filter at all? this is the first tiem i have ever heard someone say that. this problem can happen with any kind of filter?

If that is indeed the case, you haven't been paying attention to any of the discussions of the pros & cons of filters. Some people prefer to use filters to protect the front lens element, but others (like me) prefer to use the lens hood instead. A filter always degrades optical performance to some degree, although the degree of degradation may not be noticeable in some cases. In this instance, it is quite noticeable. If you must use a filter buy the best multicoated one you can afford, like B&W.

[abaazov]

so not even polarizing filters?
amnon


n.b.: no i havent read any filter threads recently..i'll look them up.