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05-01-2012, 06:26 PM   #1
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Issue with Ultrawide lens with CPL filter

I am new to DA 12-24mm. And I also purchased HOYA HMC Pro-1 CPL filter. I took the picture at evening time. If the lens is pointing to 12 o'clock, then the sun is about 9. Is this a common issue?




05-01-2012, 06:46 PM   #2
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QuoteOriginally posted by ohce Quote
Is this a common issue?
Yep, that is a tornado forming, it happens all the time in the "Midwestern" part of the states but perhaps it is uncommon there??
05-01-2012, 07:03 PM   #3
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I don't get it. I am not talking about the weather. The sky is clear. But with the CPL filter, you can see the middle of the image is darker than other portion. Without CPL, everything is fine. So I am asking if any 12-24 users have the same issue.

I have kit lens DA 18-55mm with CPL, no such issue whatsoever.

QuoteOriginally posted by littledrawe Quote
Yep, that is a tornado forming, it happens all the time in the "Midwestern" part of the states but perhaps it is uncommon there??
05-01-2012, 07:12 PM   #4
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That is a particularly severe case, but yes CPL filters do not play nice with ultra-wide lenses. I am sure someone here smarter than me can give you the technical explanation. I notice it on my DA*16-50 if I get too close to the wide end. You should use a CPL at 90 degrees to the sun for best results, most effect. I think that is what you did if understand you but the wide angle lens is causing the issue. Try the same shot at 12mm, 18mm, and 24mm to see what happens as you change the focal length.

05-01-2012, 07:15 PM   #5
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QuoteOriginally posted by ohce Quote
I have kit lens DA 18-55mm with CPL, no such issue whatsoever.
You can begin to have the same issue with the 18-55 at the wide end of the lens, but its more noticeable on a wider lens, like the 12-24. Polarizer effect is not constant, but is more prominent at a right angle from the sun. With a wide angle lens, you can capture enough of the sky so that you can see where the effect lessens. If you're going to use the polarizer on the 12-24, you're going to have to keep the lens around 24mm when used in landscape orientation. The wider you go, the greater potential for issues, and you won't be able to use it at all much past 20mm, unless you want to shoot in portrait orientation.
05-01-2012, 07:17 PM   #6
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@littledrawe

That is the best reply to a thread/question I have seen thus far this week - too funny
05-01-2012, 07:25 PM   #7
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QuoteOriginally posted by ohce Quote
I don't get it. I am not talking about the weather. The sky is clear. But with the CPL filter, you can see the middle of the image is darker than other portion. Without CPL, everything is fine. So I am asking if any 12-24 users have the same issue.

I have kit lens DA 18-55mm with CPL, no such issue whatsoever.
Polarizer 101

It has nothing to do with the lens per se and everything to do with FOV and the angle of light coming from the various parts of the sky. This is a well-known behavior of ALL polarizer filters, not just the CPL. A stitched image taken with a 50mm lens and polarizer over the same range of sky would show the same variation in color and darkness. That is one reason why polarizers have limited usefulness with ultra-wide angle lenses.


Steve


P.S. The issue is usually not particularly evident in the viewfinder...

Last edited by stevebrot; 05-01-2012 at 07:31 PM.
05-01-2012, 07:28 PM   #8
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Thanks, I try to refrain but sometimes I just can't help myself!

05-01-2012, 08:51 PM   #9
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ive never seen such an extreme case, even when using it on my 10mm, but yes, that is a perfect example of the uneven polarization effect alright.
05-01-2012, 09:13 PM   #10
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Should be pointed out that that is actually what the sky looks like. It's just that the polarizer and wide angle lens combination makes it "obvious".
If you look carefully at the sky even without polarized glasses you will clearly see the darker band across the sky.
If you take the same shot without the polarizer, there will still be a dark band across the sky in the same place, but it will be less clear.
05-01-2012, 09:36 PM   #11
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Entertaining thread!
05-01-2012, 09:48 PM   #12
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The only time I'd use a CPL on my 12-24 would be on a grey wet day or forest to knock down glare. Else you are bound to get the variations like the OP. No CPL here, just a good lens with good coatings.
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05-02-2012, 12:16 AM   #13
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QuoteOriginally posted by ohce Quote
I am new to DA 12-24mm. And I also purchased HOYA HMC Pro-1 CPL filter. I took the picture at evening time. If the lens is pointing to 12 o'clock, then the sun is about 9. Is this a common issue?

Wow that's the most perfect example of how with a sky a polarising filter shows the most effect at 90 deg to the Sun.
05-02-2012, 06:19 AM   #14
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QuoteOriginally posted by littledrawe Quote
Yep, that is a tornado forming, it happens all the time in the "Midwestern" part of the states but perhaps it is uncommon there??
QuoteOriginally posted by ohce Quote
I don't get it. I am not talking about the weather. The sky is clear. But with the CPL filter, you can see the middle of the image is darker than other portion. Without CPL, everything is fine. So I am asking if any 12-24 users have the same issue.

I have kit lens DA 18-55mm with CPL, no such issue whatsoever.
I think littledrawe was trying to have a bit of humor here. The impact is the result of the difference in impact of polarization as you cover a huge amount of sky

I tend not to use a polarizer at all with ultra wide lenses because you cannot get uniform skys.
05-02-2012, 06:31 AM   #15
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QuoteOriginally posted by littledrawe Quote
Yep, that is a tornado forming, it happens all the time in the "Midwestern" part of the states but perhaps it is uncommon there??


Ultra wide angles will always have problem with cpl filters and blue sky - however you don't need to use a cpl filter on 12-24. The blue color can be selective adjusted in post processing after your own taste - light/dark blue or nearly black/blue if you like.
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