CA with UV filter

[rick55]

When I wondered about CA with an extension tube (this thread), one suggestion was to remove any filter(s). That made me think of the threads that pop up from time to time about "Should I keep a UV filter on my lens at all times?" So I figured I'd check any influence of my UV filter on CA.

I used a different target than in the other thread, wanting to get a sharper edge. I shot the test target for Imatest. The angled square in each of these shots is near the lower left corner of the image. It's 20% of the image height from the bottom, 10% of the width from the left. This is a crop of an 800x800 piece, no sharpening, no resize.

As you can see, there's a couple of pixels of CA on the left and right edges, as expected from the lens specs and previous testing, but there's no difference with and without the filter. This agrees with what I think is the consensus. But I figured that if I took the trouble to do the test shots, I might as well post them.

The filter is a Canon filter, but I can't really recall why I bought Canon.

No filter:


With filter:


Cheers,
Rick

[Dave Humphries]

~ But I figured that if I took the trouble to do the test shots, I might as well post them.

Thanks Rick, It's always nice to see it with one's own eyes.