07-26-2010, 12:24 PM
[quote name='genotypewriter' timestamp='1280131520' post='1311']
Thanks. I guess it depends on what people need. Personally, I prefer not to do any context sensitive digital fixing, if any fixing at all, because even the best of it can't bring back what was lost in the capture.
I think I'm with Wim on this one... but I got a chance to try out a CP.2 85 T2.1 on a 5D2... an extremely well behaved lens fully wide open. Shot a bright light in the corner of the frame and saw zero fringing... CA was very very little.
[/quote]
CA can be an exception, depending on which colour(s) are the offending one, and the method of CA "correction".
I am not totally sure, but to me (having looked at samples) it seems that for instance Nikon does not correct CA in-camera (shooting JPEG) "correctly". It seems to filter out coloured edges. Again, I can be wrong in my perception.
La CA is basically one colour of light (or more) bending more (or less) through the optical system than the other colours. This means that if for instance the red colour is bending less, the projected red image is smaller on the captured image than the projected green and blue images.
Two ways to correct LaCA:
Of course, lower CA in lenses is by far preferable.
Thanks. I guess it depends on what people need. Personally, I prefer not to do any context sensitive digital fixing, if any fixing at all, because even the best of it can't bring back what was lost in the capture.
I think I'm with Wim on this one... but I got a chance to try out a CP.2 85 T2.1 on a 5D2... an extremely well behaved lens fully wide open. Shot a bright light in the corner of the frame and saw zero fringing... CA was very very little.
[/quote]
CA can be an exception, depending on which colour(s) are the offending one, and the method of CA "correction".
I am not totally sure, but to me (having looked at samples) it seems that for instance Nikon does not correct CA in-camera (shooting JPEG) "correctly". It seems to filter out coloured edges. Again, I can be wrong in my perception.
La CA is basically one colour of light (or more) bending more (or less) through the optical system than the other colours. This means that if for instance the red colour is bending less, the projected red image is smaller on the captured image than the projected green and blue images.
Two ways to correct LaCA:
- Filtering colour edges. This indeed does not fix, nor bring back what was lost. The muddy fuzziness brought on by the CA remains.
- Shrinking or expanding the "offending" colour channel. This will bring the image of that channel in line with the rest. This will get rid of the coloured edges on contrasty areas, and it will get rid of the muddy fuzziness. This method does fix what was wrong, and you gain sharpness and contrast.
Of course, lower CA in lenses is by far preferable.