art copy with lights cross polarized

[michaelnotar]

im familiar with photographing paintings and using 2 lights at 45 degrees for even light across the entire painting. sometimes i even polarize the lights and lens. curious to know if i need maintain the lights at 45 degrees if i am cross polarized... i was thinking of one light or two lights on the camera axis with c.p, which should make this usually unusable lighting setup usable.

i may be photographing a large painting, probably 50x70 or 80 inches.

my studio is about 450SF, 20x25 ft i think. i am already kindof maxed shooting 42 inch square paintings, lights at about 10ft, cant get them back much more...maybe a few inches literally.

[Jerry Skrocki]

It seems like an overly complicated set up. Why use strobes at all?
Could you achieve the same lighting with color balanced fluorescent and a longer exposure? If you are pressed for space and need softer diffused light, would a softbox work?

I am assuming there is no glass involved since they are paintings.

[BobSmith]

Originally Posted by michaelnotar

im familiar with photographing paintings and using 2 lights at 45 degrees for even light across the entire painting. sometimes i even polarize the lights and lens. curious to know if i need maintain the lights at 45 degrees if i am cross polarized... i was thinking of one light or two lights on the camera axis with c.p, which should make this usually unusable lighting setup usable.

i may be photographing a large painting, probably 50x70 or 80 inches.

my studio is about 450SF, 20x25 ft i think. i am already kindof maxed shooting 42 inch square paintings, lights at about 10ft, cant get them back much more...maybe a few inches literally.

I do a lot of this type of work. I'm not sure that I understand what you are trying to do. With large heavily textured, glossy oil paintings I frequently use the lights at a steeper angle than 45degrees. They are raking across the painting from much further to the side. If I understand, you want to put them closer to the camera. I can't imagine that would work well. The whole reason I put them more to the side is because I'm still picking up gloss spots (camera and lights are polarized) on these types of paintings at 45 degrees. You are working in a very limited space for what you want to do but it can probably be made to work if you have good lights and are careful.

Flourescents add a whole other set of problems. There are much better ($$$) continuous lights if you really want to go that route. If you have a camera that can work with strobes (ie not a scanning back camera) that's the simplest way to very high quality images.

Bob Smith

[michaelnotar]

Gerald- softboxes dont work with cross polarizing lights because they obviously diffuse/scatter the light, which is counter productive to what polarizing them does. (as i hear, i havent used diffused yet, but i do have 2 4x6ft SBs that i could do if no polarization was required.)

assume i want to keep with the hard light method, i was thinking of getting 16" reflectors for the head vs the 11s i have now or perhaps the 7" umbrella wide angle ones i already have would be better. i need to keep it small since the light polarizer gels are only 17" wide. also when i am cross polarized with 2 lights w/11 parabolics im running each head at 2400 ws and getting f8 by the tiime i polarize the lens and im shooting iso 50.

cross polarization eliminates all reflections, its really cool and different looking, glass wouldnt cause a problem i believe. theres are neat page online, regarding cross polarization and nature photography, the sample images are of a wet frog.

Bob- im trying to light up a larger area evenly lit. i would prefere to keep the light reflector size small so i can polarize them if the client wants that. but perhaps the only option i have for this situation is to use the 4x6 softboxes at 45 degrees. perhaps the 7" parabolics will work, it has a very wide coverage.

[BobSmith]

That's why I say your space is too small. The easiest way to achieve even light is to get the lights further from the subject. Really well tuned head/reflector combos that throw a broad even light can help you work in a tighter space also.

I've used a single Larson 4x6 softbox without the center diffuser to give a directional, yet soft even light to large paintings. I do this when the surface of the work needs directional light to show texture. I position the box near the painting and pointing just very slightly back towards the camera. In other words only the feathered edge of the light is hitting the painting. Exact placement is critical but you can get very even light on a large surface this way. That softbox has just the right amount of falloff at the edge to pull this off. Highly inefficient but works well. I don't use that type of lighting very often... most is done with a cross polarized setup similar to what you describe.

Ideally I like to work with two 2400ws packs (Calumet Elite)... one per head in a cross polarized setup. Currently one is down and I'm using one for both heads. I get something like f7.4 @ ISO 100. My shooting space is approximately 30x40. That lets me get the lights a little further away.. and it lets me get the camera further away and shoot with a longer lens which helps as well. I use a Canon 180mm Macro for all but the very largest pieces. I use a 100mm Macro for those (on a 5D).

Bob Smith

[Mark Swindler]

Michael- I've photographed literally hundreds of painting over the last 28 years, and I use studio strobe to do it. Start by setting the painting an an easel, as vertical as possible. I set the lights at about 45degrees from the camera, and hang a sheet of polarizing material about 6-8" in front of the strobe head(using the standard umbrella reflector. I then meter the light with a Minolta Flashmeter V, metering the center, all four corners nad the top and bottom center of the painting. Adjust both lights in and out, up and down and rotate them right and left until the light reading are equal. As little as .2 of a stop is visible in the final image. Once you have the light even, set up your camera, any format, film or digital, and get the camera parallel to the art work. At that point I slide on the polarizing filter and look through the lens, rotating the filter until the reflections disappear. Actually what is happening is you are rotating the polarizer so it's axis is 90degrees from the axis of the polarizing sheets. The sheets will be marked, so be sure and hang them the same direction.
Whatever the meter tells you, open the lens 1-1/2 stops, and your exposure will be very close.
I have found that bellows draw in 4x5 will affect your exposure by about 1/2 stop, so bracket your exposures. I also shoot a Kodak color strip in every film shot, so if it's ever reproduced by a printer they can get the color precise(maybe)!
I always shoot a calibrated gray card in the first frame of any digital images so I can set the precise color in Lightroom. It also goes without saying that the client, if they are doing any reproductions(Giclee prints) they will need an uncompressed Tiff file as big as possible. That being said, I don't convert the raw files to 16 bit tiffs unless the client requests it.
Well, that's my set-up. I hope that helps!

Mark S.

[michaelnotar]

thanks Mark, thats what I do, but good to hear it reinforced.

Mark, my polarizing filters for the lights are showing wear, they are a little bit green and lighter in the center, what is the life of the filters.... how long do you go before changing them out.... Unfortunately they are like $42 each (Rosco 17x21"). i have photographed about 15 paintings with them, maybe 100- 2400ws pops were done on them.

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