Polarizer vs. 29A Red

greenspun.com : LUSENET : Large format photography : One Thread

I am looking to add some additional depth to the sky area in my black and white landscapes. I have used a 29A red filter and this does give the results of a darker sky rather well. A few years back I tried to use a Polarizer to see if there was a noticable difference. While the sky area was much darker and had the effect that I wanted with the Polarizer, I did get a significant amount of vignetting around the edges of the negative. This was with a 14" Kodak Ektar lens mounted on an 8x10. I did not think that I should see any vignetting when using a standard lens in this situation. I wish to use a Polarizer again with a 10" lens mounted on a 5x7. Is there any problem with this or by using a Polarizer am I bound to get vignetting? Am I just missing something?

-- Bruce E. Rathbun (brath@iquest.net), December 30, 2000


Bruce: When using a wide angle lens, the amount of polarization of the sky will vary across the field of view, since the darkening is a function of the angle between the lens and sun. So the polarizer may produce a more variable darkening of the sky which can look like vingnetting, or like inverted vignetting depending on geometry of the shot.

-- Glenn Kroeger (gkroeger@trinity.edu), December 30, 2000.

Bruce, with a 10" lens on a 5x7 there shouldn't be any problem.

-- lsmft (Bmitch@home.com), December 30, 2000.

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