CROSS POLARIZATION with flashes ans umbrella !

[Jox]

Advertisement (gone after registration)

Hello,
I use cross polarization for bright subjects photographed with 2 flashes (D2 Profoto).
I need wide distribution.
I placed the polarized filters on the flashes, which are directed towards umbrellas (indirect lighting standard).
The choice of the angle of these polarized filters seems to me to have a much less detectable effect than in direct lighting! It's very difficult to fine it ! Is the angle offset from that which works in direct lighting? Are there any tips? ...
I would be interested in experiments on this subject http://www.hasselbladdigitalforum.com/Smileys/default/wink.gif
thanks in advance !
Alain from France

[John McMaster]

An umbrella is used to diffuse light, so a polarizer has less effect than with direct lighting.  Try a softbox with polarizer?

john

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[Jox]

Hello John,
Thank you very much !
I'm putting away my umbrellas and I'm looking for a system of bowls (perhaps the traditional Profoto zooms, quite versatile, but a bit expensive...) to easily attach the filters, or soft box ...
My subjects are paintings that have been varnished quite glossy.
Best regards!
Alain

[Jox]

I also have 2 Hedler led Fresnel 185W. I wonder if that wouldn't be a cross-polarized idea too...

[davidmknoble]

Dumb question having never done this, would two or three images with lighting from different angles be able to be combined like and HDR photo to remove glares?  Sort of a combine detail from different shots removing bright spots?  It seems like this is difficult process, high gloss oils, good lighting but not wanting shadows from the paint surface.

Really interesting.

[Jox]

Oh, David ! An anti-reflective polarized fusion!

It's very exciting ! But I'm wondering how to tell the processing to prefer non-reflective areas? To study...  

[ynp]

Advertisement (gone after registration)

I use the Rosco polarization film over the strip lights (softboxes) when copying pictures. And a circular polarizer on the lens. In my experience the soft boxes work much better with the polarization film materials and grids on the diffuser panels would improve the quality of the light. 
https://emea.rosco.com/en/product/polarizing-filters

[ynp]

3 hours ago, davidmknoble said:

Dumb question having never done this, would two or three images with lighting from different angles be able to be combined like and HDR photo to remove glares?  Sort of a combine detail from different shots removing bright spots?  It seems like this is difficult process, high gloss oils, good lighting but not wanting shadows from the paint surface.

Really interesting.

Hi David. Yes. That’s the idea. When copying oil painting we face a problem with the glare on the surface of the picture. If you kill all the reflections with the cross polarization, the painting became technically correct but lifeless. So the best way is to combine several exposures with polarization and without. Sometimes I add an exposure with the side lighting to expose the structure. Mix everything to taste. 
 

yevgeny

[Pieter12]

On 7/15/2022 at 1:11 AM, Jox said:

Hello John,
Thank you very much !
I'm putting away my umbrellas and I'm looking for a system of bowls (perhaps the traditional Profoto zooms, quite versatile, but a bit expensive...) to easily attach the filters, or soft box ...
My subjects are paintings that have been varnished quite glossy.
Best regards!
Alain

You can put the polarizing gels in a frame that is positioned in front of the strobe head (either on a stand or by making a frame that is attached through the umbrella slot in the strobe base), I do it all the time for paintings. Just watch the heat from modeling lamps. Make sure both gels are the same orientation and the strobes are evenly distanced and at 45º from the painting's surface. It is easy to check this by placing a pencil or chopstick at the center and perpendicular to the painting and see if the shadows on both sides are equal. Also meter across the surface of the painting for evenness of lighting. And don't forget to use a circular polarizer on the lens. Polarizing can change colors slightly, either making them more intense or dulling them down. Shoot a color chart as a reference so you know if any correction needs to be made in post. Also, if you remove all the reflections, you may lose some of the texture that is part of the painting's character. You will need to experiment with how much polarization you introduce with the polarizer on the lens.

[Jox]

Hello Pieter,

Thank you for this synthesis of the very useful photo technique of reproduction of paintings.
I have been using a colorchecker and the profiles very easily made by Phocus for a long time, but for non-reflective paintings (rice paper without varnish and without glass...).
It is only recently that I have to take photos of varnished paintings.
I now have, thanks to the friendly sharing here, elements that I put in place and which bring a lot of improvement (cross polarization...).
I still have to experiment a little more to find the right polarization for a good rendering, aesthetic and realistic.
I noticed that the colorchecker/Phocus profile allows to obtain very similar results, with flashes or Led Hedler Profilux led 1000.
I like the practical side of the Hedlers, in direct lighting with barndoors. I saw an accessory that allows you to mount a polarizer on the Hedler binding, but I couldn't find where to get it! Its only drawback seems to be not being able (without tinkering) to add barndoors. I indicate the link, if the forum knows where to find this wonder...

https://correlatedsolutions.eu/polarization-filter-for-hedler-led-2/

Thank you all once again
Alain from France