Advice Needed on Appropriate Use of Polarizers with Wide Angle Lensesgreenspun.com : LUSENET : Large format photography : One Thread
Is anyone out there succesfully using polarizer filters with their wide angle lenses in landscape scenes with near-cloudless skies?
Boy, I just "experimented" with shooting 4x5 tranparencies with a 90mm lens using a polarizer for the first time. Despite efforts to insure an evenly polarized sky in the ground glass, the sky came out uneven in all of the processed shots. (and yes, as a double whammy, the old mechnical vignetting from stacking the polarizer and a warm - up filter, and the on top of that, using shift - I was really asking for it!). Anyway, in some cases, the shift in tonality seemed unnaturally abrupt across the sky.
In general then, what are the techniques and conditions under which one can use polarizers on 90mm or 72mm large format lenses for example? Is it even possible to get an evenly polarzed sky across the large 4x5 sheet? Thanks for your input. Andre
-- Andre Noble (email@example.com), September 25, 2001
Hi Andre -
Unfortunately, you're butting heads with physics. Polarization in the sky varies with the angle from the sun, being strongest at 90 degrees. So, if the sun is near the horizon, the sky near the zenith will be most darkened with a polarizer.
Any wide-angle lens will cover enough sky such that polarization will vary across the frame.
To quote Cmdr Montgomery Scott, "You canna change the laws of physics!"
Peace and good light.
-- Kevin Bourque (firstname.lastname@example.org), September 25, 2001.
Well, I don't really have an answer here, just more questions really. I too have had this problem with a Schneider Super Angulon XL 47mm lens on my 6x12 rollfilm back. With the lens stopped down to f/16-22 using a polarizer, I don't see any vignetting. The entire frame looks very acceptable. Yet when I get the Fujichrome or Ektachromes back, there is some major vignetting! I wasn't so much trying to avoid uneven skies. I don't mind some uneven polarization, but I absolutely dislike uneven exposure.
After speaking to one of Schneider Optics' techs about this problem, he described several things that have contributed to the vignetting. 1)The cos4 (?) problem of the light bending too much in wide angles. He recommended a $400 center filter to tackle that. 2)The film is flat. Can't do much about that. 3)Chromes are really bad for these kinds of "contrasty" situations. He recommended shooting negatives because they have a greater exposure latitude.
But I still wasn't satisfied...
I looked at Schneider's website (http://www.schneideroptics.com/filters/filters_for_still_photography/ slime-line) on slim-line filters and this is what I found:
"Have you ever photographed a beautiful landscape with your wide- angle lens, rotating your polarizer just right, only to be surprised to find four black corners in all of your photos?
The B+W Slim-Line Filter is specifically made to work with wide-angle lenses. The unique "slim" design prevents vignetting with lenses as wide as 20mm. Available in a broad range of filter types in sizes 49mm through 105mm, Slim-Line filters are the perfect choice for your wide-angle photography."
This sounds like Schneider is saying that the GLASS thickness could have something to do with the vignetting as does the filter rings. The reason I'm thinking this is because Schneider is saying when you look through the filter during composition, there isn't any noticeable vignetting, but when the film comes back, there is. If there were mechanical vignetting from the rings, we should be able to see it with the lens stopped down, shouldn't we?
So my question is... Has anyone used these slim-line polarizers on wide-angle lenses? If so, did they reduce the vignetting problem?
Please cc your response to my email address, as I do not visit here often. Thanks.
-- Eric Nishibayashi (email@example.com), November 20, 2001.