Dear Glyn
Every time I read bad reports about the 17-40 L lens I start worrying. Recently, during a period of baroque worry, I did a few tests. My conclusions are that the CA is nothing like so bad in C1. Why this should be I don't know. I had been doing some conversions in Adobe PS CS and found the quality lacking and the settings needed much more work than in C1 but at the same time I was impressed with the slider to remove CA. I then looked at the results in C1 and decided the quality gain was worth the extra fringing.
I cannot think of a repro circumstance where this fringing would be noticeable and I wonder if we worry too much about faults which are only showing because of the increased detail we now expect.
The red highlights are surely another issue and not CA. These are virtually non-existent with C1 although I can see them clearly in the preview. After processing they are not there. Are they caused, in your case, by slight camera or subject movement?
Bob Croxford
On 10 Jun 2004, at 11:33, Glyn Davies wrote:
Dear Simon,
I don't wish to throw a spanner in the works here, but as a IDs user who shoots hundreds of landscapes there may be an issue! I have been getting horrendous CA from Canon's 17-40L lens, which from a landscape point of view is a critical lens. The Camera Raw (in my experience) counter this. It only works for edge CA but the big problem I'm getting is in or near the middle. For any general subjects there is NO problem but if you shoot into the sun at say the sea or sparkly rivers, you may find serious red highlights. It doesn't matter whether you shoot RAW or jpeg. I have had to spend much time creating HS adjustment layers to mask out the problem areas but it really pisses me off that I have to.
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