Tim Kuang Offline Upload & Sell: Off
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Hi folks,
After some further thoughts, I found I still have some questions. I noticed that with my Canon ef 17-40 f4L lens, I sometimes get uneven polarization, sometimes I don't. It is this lack of predictability with my wide angle lens that frastruates me from time to time . In my impression, the uneveness in the middle seems to be related to the elevation of the sun: all my photos having uneveness in the middle seem to have the sun in the low horizon and I was 90 degrees to the sun.
Since I really like Dave's polarizing band explanation, I am going to use that. Is it possible that the width of the band is changing depending on some conditions, say the elevation of the sun, or the atmosphere, or even the angle to the sun? When the width of the band is small compared to the AOV, it is easy to see unevenness either in the middle or on the side depending on your angle to the sun. Any ideas?
Thanks,
--Tim K.
ps Charles, I would love to see your images if you have time (probably together with a short description how you corrected them ). I have been using Gradients to correct the problem, but like to know more tricks. Thanks.
pps. Al, unfortunately with the small viewfinder on my Digital Rebel xt, it is not easy to tell the polarizing effects.
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