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10-27-2017, 01:14 PM   #1
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Singh-Ray Gold 'N blue polarizer

I really like using this polarizer. Or at least I did. Just picked up a roll of Velvia from the lab, and for some reason this polarizer vignettes very significantly... I've used it with P645 without any problems in the past. This time I used it with a 10 stop ND filter and I suspect that the longer the exposure time, the darker the vignette. Mind you, that's just a hunch after looking at the slides. I haven't scanned them yet. The darkest vignette is just plain black. Looks like one of those 180 fish eye lenses that give you a circular photo in a black box...

Have you guys had such experience? Just want to figure it out so I can avoid it in the future...

10-27-2017, 01:36 PM   #2
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Just a thought - some ND filters are actually just stacked polarizers (especially variable ND filters). Could this interfere with the polarizing filter? Maybe you can tell what the brand and model of the filters are
The other possibility is that two filters are so thick that it darkens the edges. This is usually only a problem with very wide angle lenses. Some brands make special "thin" filters for those
10-27-2017, 02:18 PM   #3
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QuoteOriginally posted by Na Horuk Quote
Just a thought - some ND filters are actually just stacked polarizers (especially variable ND filters). Could this interfere with the polarizing filter? Maybe you can tell what the brand and model of the filters are
The other possibility is that two filters are so thick that it darkens the edges. This is usually only a problem with very wide angle lenses. Some brands make special "thin" filters for those
I used a B+W 10 stop ND filter. I can't remember which model it is, as B+W make a lot of differently priced filters. I've never noticed any vignetting with the ND filter only, and I've never had any vignetting on a crop sensor...
10-27-2017, 02:54 PM   #4
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Are you stacking threaded filters? Some are made to barely keep out of range of the widest focal length and stacking another will vignette where the filter ring is cutting off the image,.

10-27-2017, 03:30 PM   #5
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I think amoringello has the answer.
10-27-2017, 03:55 PM   #6
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QuoteOriginally posted by Canada_Rockies Quote
I think amoringello has the answer.
I hope it was that simple.
To be fair, I think Na Horuk said it first. Somehow I missed his comment when I wrote my suggestion. :-)
10-29-2017, 08:47 AM   #7
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QuoteOriginally posted by amoringello Quote
Are you stacking threaded filters? Some are made to barely keep out of range of the widest focal length and stacking another will vignette where the filter ring is cutting off the image,.
I had to think about this... I definitely had the gold and blue polarizer and a 10 stop ND filter. Both are threaded, but I never had a vignetting problem with them before. I used them both on K-5 and P645. But I think this time I might have had a Kenko ND filter as well... I think it might have been attached to the polarizer and I couldn't remove it without the filter tool (or whatever it's called). I never had vignetting problems with that Kenko and polarizer, and I didn't have a problem with the kenko, the B+W and the polarizer together last week either.

Looking at the scans, it seems that the severity of vignette is related to exposure time - is that possible? Maybe with shorter exposure times on a crop sensor vignette is just not visible? This one is very red, so you know exposure was very long, a couple of minutes for sure...

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10-29-2017, 09:04 AM   #8
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QuoteOriginally posted by IgorZ Quote
I had to think about this... I definitely had the gold and blue polarizer and a 10 stop ND filter. Both are threaded, but I never had a vignetting problem with them before. I used them both on K-5 and P645. But I think this time I might have had a Kenko ND filter as well... I think it might have been attached to the polarizer and I couldn't remove it without the filter tool (or whatever it's called). I never had vignetting problems with that Kenko and polarizer, and I didn't have a problem with the kenko, the B+W and the polarizer together last week either.

Looking at the scans, it seems that the severity of vignette is related to exposure time - is that possible? Maybe with shorter exposure times on a crop sensor vignette is just not visible? This one is very red, so you know exposure was very long, a couple of minutes for sure...
That is more than normal vignetting. It definitely looks like the filter ring.
It is easy to tell, unscrew the filter-set, and hold them up in front of the lens. Then move them around a bit. You'll see quickly if it is the rings, or something else.

You'll definitely see it more or less with different t focal lengths. Zoom in and you'll see less.
Bright exposures might make it less, but I don't believe I've ever seen an extreme difference. Smaller aperture might have some effect. (???)
I have a few that I used to stack regularly, and just dealt with the filter ring issue. (I did finally buy a 10-stop ND filter, and do not have the issue any more. :-) )
10-30-2017, 09:57 AM   #9
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QuoteOriginally posted by amoringello Quote
That is more than normal vignetting. It definitely looks like the filter ring.
It is easy to tell, unscrew the filter-set, and hold them up in front of the lens. Then move them around a bit. You'll see quickly if it is the rings, or something else.

You'll definitely see it more or less with different t focal lengths. Zoom in and you'll see less.
Bright exposures might make it less, but I don't believe I've ever seen an extreme difference. Smaller aperture might have some effect. (???)
I have a few that I used to stack regularly, and just dealt with the filter ring issue. (I did finally buy a 10-stop ND filter, and do not have the issue any more. :-) )
thing is, it's a 72mm filter, and I used it with K 28 f3.5, which has a 52mm filter diameter. So it is weird...
11-03-2017, 09:46 PM   #10
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So a step ring and two screw-in filters and super-long exposure...maybe this combo rules itself out?
Drop the filters one at a time and see what happens...may not get the image you want but should get answers.
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