Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: nortonc on February 24, 2006, 12:22:59 pm

Title: Canon 20D Chromatic Aberration/Shadows
Post by: nortonc on February 24, 2006, 12:22:59 pm
Hi,
I've been shooting with a 20D for the last year or so and have begun printing imagery via large format inkjet. I just realized that I am seeing a consistant purple tweak in images that are shot with extended exposures in lower light conditions and in other instances where the subject matter is fairly cointrasty. The purple appears as shading that follows the transition from moderate to deep shadow into midtone.  
This issues shows up consistantly and once you see it it's pretty annoying.
Wanted to see if anyone else is experiencing this issue.
Title: Canon 20D Chromatic Aberration/Shadows
Post by: DarkPenguin on February 24, 2006, 12:36:26 pm
Post an example.

Does this occur with a specific lens?  (Or lenses?)
Title: Canon 20D Chromatic Aberration/Shadows
Post by: benInMA on February 25, 2006, 11:14:33 am
It's a lens issue... not likely to be the camera.
Title: Canon 20D Chromatic Aberration/Shadows
Post by: nortonc on February 25, 2006, 05:46:17 pm
Same problem happens with multiple lenses.
All so far...Canon Ef and EFS
18-55
10-22
Seems to be a weird color break that shows up as purple in transition areas.....samples attached.
Shows up in color and in images converted to RGB B&W.

Check these out.
Title: Canon 20D Chromatic Aberration/Shadows
Post by: dwdallam on February 26, 2006, 04:40:15 am
I had purple fringe problems when I first used my 20D at night with a 70-200 L lens, and man was I pissed. It was pretty bad. Well, I found out waht it was. I accidentally bought glass, no couting UV filters--that I use on all my lenses. after I replaced them with Multicoated filters, the fringe went away. BTW, using the Multicoated Pro Hoya UV filters seems to cut down even more fringe than using the bare lens. However, make sure you get MULTICOATED, not "coated" etc.

Quote
Same problem happens with multiple lenses.
All so far...Canon Ef and EFS
18-55
10-22
Seems to be a weird color break that shows up as purple in transition areas.....samples attached.
Shows up in color and in images converted to RGB B&W.

Check these out.
[a href=\"index.php?act=findpost&pid=59061\"][{POST_SNAPBACK}][/a]
Title: Canon 20D Chromatic Aberration/Shadows
Post by: nortonc on February 26, 2006, 10:13:34 am
Quote
I had purple fringe problems when I first used my 20D at night with a 70-200 L lens, and man was I pissed. It was pretty bad. Well, I found out waht it was. I accidentally bought glass, no couting UV filters--that I use on all my lenses. after I replaced them with Multicoated filters, the fringe went away. BTW, using the Multicoated Pro Hoya UV filters seems to cut down even more fringe than using the bare lens. However, make sure you get MULTICOATED, not "coated" etc.
[a href=\"index.php?act=findpost&pid=59087\"][{POST_SNAPBACK}][/a]

Thanks for the feedback....I am using UV filters on all of my lenses......Guess they might make good coasters eh.
Much appreciated.
Title: Canon 20D Chromatic Aberration/Shadows
Post by: dwdallam on March 04, 2006, 06:26:05 am
Quote
Thanks for the feedback....I am using UV filters on all of my lenses......Guess they might make good coasters eh.
Much appreciated.
[a href=\"index.php?act=findpost&pid=59102\"][{POST_SNAPBACK}][/a]


Unless they are multicoated, they are as good as glass frisbees.