Polarisation Filter

[Drew Wiley]

I have some nice polarizing filters, but other than for cross-polarization of high gloss prints in copy-stand mode, don't use them whatsoever. I live for reflections, even when shooting cars. But I suppose every studio at least needs that option laying around somewhere, just in case.

[Pieter]

I use polarizing filters on lights in combination with a polarizer on the camera for copying paintings. Just need to watch out for color shifts due to the polarizer.

[LabRat]

I tend to just treat a polarizer filter as a 1 stop ND filter, as the extra cut is usually used for suppressing highlights, and usually just partially polarize outdoor stuff, then maybe allow an extra 1/3 stop depending if shadow areas even darken at all...

Used to use cross-polarization in the studio sometimes, which could cut reflections on tough stuff like shooting a plastic bag full of vegetables, but at the cost of subject looking green, maybe covered with spectra, and "dead" looking...

Avoided it for art repo as paintings tended to look "dead" and color shifted... Usually there was a lighting set-up for excessively textured works that could be used instead (like using 2 soft boxes for cross lighting etc)...

Could be useful for copying foto prints with excessive old surfaces, like the surface with concentric rings often on wedding prints...

Polarization could be the disease, not the cure... :-0

Steve K

[Bob Salomon]

Doremus,

The only thing I can attribute the difference to in exposure with the 90 f8 is lower transmission. The lens if I recall is an 8 element biogon design vs the almost symmetrical 6 element plasmats of my other 3 lenses. 1/2 stop add exposure required no matter the shutter speed vs my other lenses.

Used the 90 f8 for maybe 75% of my shots with the 300mm next eventually.

I don’t tend to analyze the whys, just find a solution and stick with it, of course unless someone provides something better.

“Convoluted”, well ok, will edit posts more carefully.

Have you had the shutter speeds on that lens professionally checked?

[Drew Wiley]

It's hard to reproduce paintings well due to the variables of gloss & reflection, impasto, and inevitable hue shifts under polarization; likewise, high gloss prints like Cibachrome, especially when large. When I was involved with paintings at the copy stand, it was mainly forensic anyway, sleuthing this or that art-fakery. Now there are far fancier ways of doing that. With antique photo restoration via re-printing, a polarizer could help by removing the sheen of "bronzing" due to under-fixing or even fire stain.

[LabRat]

Other filters were useful for B/W also... A studio exec from Capitol Records had a stack of badly fading/stained publicity 8X10's all signed by their recording artists to her, but prints were nearly history... I copied them 35mm Pan-X with a stack of 29 red + polarizer, then printed higher contrast to even densities out... She was shocked, said they looked like new!!! ;-)

Steve K

[Drew Wiley]

Yeah, I always had a 29 red filter around the copystand. But my favorite forensic film was TechPan, deliberately engineered for "tech" purposes. For restoration copy work, I generally shot TMax or FP4 in sheet version. My then copy rig could accommodate a Sinar monorail setup. My current setup is way more deluxe, but designed for just SLR's, whether P67 MF or 35mm film Nikon or DLSR. Hope to catalog my personal print collection with it, once I have enough Pepto Bismol on hand to even tolerate working with digital files. Not my cup of tea, though I've done it before, but only web-related, never for original shots per se. Have no interest going there. I built a nice darkroom space for a reason.

[Doremus Scudder]

Doremus,

The only thing I can attribute the difference to in exposure with the 90 f8 is lower transmission. The lens if I recall is an 8 element biogon design vs the almost symmetrical 6 element plasmats of my other 3 lenses. 1/2 stop add exposure required no matter the shutter speed vs my other lenses.

Used the 90 f8 for maybe 75% of my shots with the 300mm next eventually.

I don’t tend to analyze the whys, just find a solution and stick with it, of course unless someone provides something better.

“Convoluted”, well ok, will edit posts more carefully.

I've got the Nikkor 90mm f/8 as well and have never noticed any difference in transmission from my other lenses. It does have a fair amount of falloff, just like other 90s, and I'm in the habit of giving a bit more exposure than indicated when things at the edges are important (I don't use a center filter, but do "center burn" a lot when printing to compensate for the falloff). I might have the lens' shutter speeds checked if I were you. Slower speeds are pretty easy to check by ear.

And go ahead and be convoluted There's too much simplification and lack of detail out there these days!

Best,

Doremus

[Alan Klein]

I've got the Nikkor 90mm f/8 as well and have never noticed any difference in transmission from my other lenses. It does have a fair amount of falloff, just like other 90s, and I'm in the habit of giving a bit more exposure than indicated when things at the edges are important (I don't use a center filter, but do "center burn" a lot when printing to compensate for the falloff). I might have the lens' shutter speeds checked if I were you. Slower speeds are pretty easy to check by ear.

And go ahead and be convoluted There's too much simplification and lack of detail out there these days!

Best,

Doremus

I use my cellphone to check shutter speeds. I just record the sound and measure the signal using Audacity, a free app. https://www.audacityteam.org/

Here's what the signals look like on a 90mm lens at 1/4, 1/8, 1/15 and 1/2, top to bottom. I've selected 1/8 shutter test the second from the top and highlighted the signal begin and end. The time appears in milliseconds at the bottom 0.124ms which when converted to a fraction is almost exactly 1/8 of a second. (1/8=0.125) The time indicated in the circle is changed to a fraction to check the actual speed. It's good up to about 1/60th. It gets a little flaky above to measure easily. But most of your shots will be at low speeds which are fairly easy and accurate to check.

[Alan Klein]

I was wondering whether this sample picture and recommendation for checking shutter speeds with Audacity should be placed in a permanent section of the forum for others to reference?