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esox
30-Jan-2013, 02:07
I'll have to shoot paintings, large and small ones. Can be up to 2x3m. The camera will be mfdb phase one on p65+ digital back. The purpose is to create catalogs and edition.

I gess that, for the large paintings I'll need 4 sources of diffuse light. 2 on each side being careful not to create some hot points in the frame of the camera.

I thought about 2 possibilities : 4 ombrellas or 4 small lightboxes.

What are your opinions and suggestions ?

It's gonna be my first professionnal paid assignment. I can't flub it !

Vaughn
30-Jan-2013, 02:39
I have photographed similar sized paintings (4x5 transparency film, Kodak 64T, I believe).

I just used two Tota lights (floods, halogen bulbs), directly on the painting -- but less than at a 45 degree angle to minimize reflection off the paint. I just moved the lights around until I got the same reading off all of the painting (actually off a grey card). Worked very well.

Suggestion -- mark off a similar size bit of wall and light it and do some practice shots. Diagram out the light placement so that you can duplicate it easily.

Vaughn

PS -- I am not a Pro, so hopefully those more experienced can confirm, add to, or trash my suggestion!

lenser
30-Jan-2013, 05:09
esox,

Textured media such as oils or acrylics will give you headaches no matter the light source as they will always reflect hot specular spots. But, I've had the most success with two or four lights that are all covered by polarizing film (which must have each sheet oriented identically) and then use a polarizing filter on the lens. Two lights are fine for smaller paintings so long as they are set at 45 degree angles to the work and are level horizontally with the mid point of the painting. On larger works, the four light set up with each again at 45 degrees but located at about level with the corners on each side is good. Make sure they stay level horizontally. Do not tilt them upward or downward toward the center of the work because that would create a brighter spot in the center of the exposure. I use normal reflectors instead of soft boxes and would not dream of using umbrellas because they uncontrollably scatter light everywhere and can't be gelled with the polarizing film.

Since you are first polarizing the light source and then using the camera Polarizer to cancel all glare from the lights (which can slightly veil the tones in even other less reflective media such as water colors or prints), your colors are as near pure as you can make them and any specular highlights are totally minimized.

Finally, find a McBeth or Kodak color chart to include at the edge of the paintings. Using this, you can absolutely match the output files to the original color in the art without any guess work.

Kodak published a well thought out booklet on copying back in the 1960's that put me onto this technique. Perhaps you can find a copy on ebay.

Good luck.

Sevo
30-Jan-2013, 07:10
Beware: The polarizer trick is most successful with black and white. In colour, it is much less foolproof as it will often cause the reflections to have a (usually blue or violet) colour cast rather than disappear entirely. Use the top of the crop of most recent polarizers, don't overheat the polarizer foils in front of the lights (they are easily damaged), and do not attempt to go past the polarizer's limits - position all lights without polarizers first so that you get minimal reflections, and cancel out the remaining reflections with polarizers then.

Besides, not all clients will want that forensic look (which will make past restorations and damage glaringly obvious), especially not for marketing materials - most of the museums I worked for wanted a "good looking natural" shot with limited reflections for catalogue publication, posters etc. and a variety of "technical" shots (black and white separations, IR, polarized colour, and texture enhancing sidelight reflection) for archiving, scientific purposes, future restoration etc.

esox
30-Jan-2013, 07:24
In my case it will be for painters for catalog purpose. So no IR is asked or any polarized colour.

What do you mean by "good looking natural" ? You mean it is not necessary to use polarized light ? Only 4 light with standard reflectors ?

Sevo
30-Jan-2013, 08:02
Carefully placed lights, right. I often got away with a few styrofoam reflectors and a single big softlight - museums usually wanted the pictures to be lit to roughly the same effect it is hung.

Drew Wiley
30-Jan-2013, 10:00
The reproduction will indeed look different cross-polarized vs non-polarized. But polarizers are often
essential. Tota light kits are nice. You can place the polarizers over frosted gels, which can be blue
for color temp correcting the halogens. Or for bigger works, use one of those PVC-pipe quickie supports for diffusion sheet. Lights on each side at 45 deg. Color temp meter helps - or test in advance
with your lighting setup. Rectilinear lens suitable for flat copy work (even field, no distortion). Might
be smart to take several shots: plain, slightly polarized, and more polarized. This will affect contrast
and its relation to hues, as well as reflections such as impasto. Any result will be somewhat artificial;
but which will the client like best? So good idea to retain options.

esox
30-Jan-2013, 17:13
The ideal would ne a set I can ise also as light flr object sculpture pictures. And also clzssiczl studio job : portrait, artistic nude'... Ansd not too expésive, I just bought the phase one equipment... Are my wishes too ireal ?

Vaughn
30-Jan-2013, 17:38
Textured media such as oils or acrylics will give you headaches no matter the light source as they will always reflect hot specular spots...

This is where the two lights set at less than 45 degrees worked for me -- probably closer to 25 degrees. Much less reflections off of the texture of the paint, yet does not totally do away with them so one can get a feel for the brush/knife work.

John Olsen
30-Jan-2013, 18:37
I'm with Lenser above. Gotta have polarizers for the lights and camera. You may have to adjust polarizer to make sure you don't get an exaggerated darkening, particularly on metallic paints. I adjust lighting and focusing with the polarizers swung out of the way. Then swing polarizers in front of lights, adjust camera polarizer quickly, and shoot before the lights' polarizers melt. If your paintings are very shiny, also draw curtains over windows behind the camera. Good luck.

Too Many Cameras
30-Jan-2013, 19:35
I have a book at home with an entire chapter on this. When I get back this evening, I'll see if I can find it. If so, I'll post some tips from it.

esox
31-Jan-2013, 01:00
Thanks

Too Many Cameras
31-Jan-2013, 01:03
The book's advice isn't basically the same as we've seen with a few added details. Note that this book is from the 1950s and focuses on black and white film. It suggests two studio lights at 45-degree angles from the camera. Then it adds that polarizing filters should be on the lights. But no mention is made of a polarizing filter on the lens (that doesn't indicate that's wrong, in fact, I think a polarizing lens on the camera would be a good idea.)

For metering, it suggests a spot reading from the image's center and each corner as well as a number of random points on the subject.

I'm assuming these are large paintings and you won't be using an additional bellows, but if you are then there's some added calculation in that.

Also, if the original is closer than eight times the focal length (e.g., 80 inches for a 10-inch lens) you'd need to increase the exposure by up to 3/4 (at 1:1).

If any of these are sculptures, it suggests lighting them as realistically as possible.

That's all I got.

lenser
31-Jan-2013, 04:02
The ideal would ne a set I can ise also as light flr object sculpture pictures. And also clzssiczl studio job : portrait, artistic nude'... Ansd not too expésive, I just bought the phase one equipment... Are my wishes too ireal ?

It is not too ideal(?) a wish at all. I can't speak for the European market, but many fine used items are available in the US via ebay including the White Lightning series of flashes that are incredibly reliable and allow for quick interchange of standard reflectors and snoots, to umbrellas, and on to soft boxes. I have owned White Lightning Ultras for over 25 years and still use them almost daily. They adapt to any needs I have from the copy work we have been discussing, to portraits and commercial assignments and all with ease.

Many other manufacturers have similar mono lights that could also be used as you wish for all applications. Please note that I am very partial to mono lights as opposed to the systems that rely on a central power source that operates four or more heads. Those are very good systems and usually quite reliable, but if your power source ever goes down.....you are out of business until you repair or replace it which might take more than a few days. With the mono lights, with power already built in each head, if one goes down, you can carry on quite successfully with the rest in your kit.

The one thing that I haven't mentioned or seen mentioned in all of your answers is that in the copy work, be sure that your reflectors are all the same style and diameter and that they are set to exactly the same power and distance in order to avoid hot spots or a different lighting pattern from one side of the piece to the other on whatever you are copying.

A couple of others have mentioned melting the polarizers that are at the lights. That is a problem only if you have them right on top of the reflectors. Simply buy large enough sheets so that you can hang them several inches in front of the light (the modeling light is the heat source) and you can leave them in place pretty much all day. The big sheets keep you from having any spillage of the raw light onto the piece and six or eight inches of space allow for adequate air circulation and for the heat to dissipate upward and not fry the material. Since they do subtract light, I second the idea of swinging at least one out of the way (temporarily) for easier focusing or, just have a bright painters light beside the camera on a separate stand that you switch on only for focusing and then switch it off while doing the photography. That gives you a much brighter focus light and keeps you from having to fiddle with what should be a static set up on all of your actual copy equipment.

Regarding the separate focus light, don't set your camera's polarizer while using the focus light. Only set it while viewing the piece under the polarized light.

Sevo
31-Jan-2013, 04:20
YMMV as to whether you may photograph with flash, if the paintings are in the care of a curator - these tend to own luxmeters and IR meters to check risks, but usually won't trust the flashmeter you bring. I often had to use constant light - the focus light on my flash heads being gentle enough to satisfy the museum staff.

Robert Langham
31-Jan-2013, 07:02
I shoot this kind of stuff often with polarizer film over two lights, (dynalite heads), a polarizer on the camera and a greycard with color scale. I'd sure recommend talking them out of using large format and shoot it on digital. Seems like I bought the polarizer film from calumet. Comes in a roll. I used those little double clamps, top and bottom, to hold polarizer film an inch or two in front of a fairly big cone reflector on the dynalites, then put a stand and a black card between the light and the camera to keep glare down. Good luck, no matter what your approach. You'll really see the reflection controlled when you spin the polarizer on the camera. On the frame and the brush strokes. Be sure that both sheets of polarizing film over the lights are turned the same way! You don't want to be polarizing ONE light and UN-polarizing the other. Just clamp them in front of the lights with the curly side toward the light and the same edge up.

Helps to shoot the artwork with the longest dimension vertical between the two lights, (Stand paintings on end)....that's where the most even illumination is- a strip evenly between two lights. But then you have to go vertical with the camera as well.

I'm sure I've over-explained this.

Bob Salomon
31-Jan-2013, 08:06
Couple of things to watch out for.
1: The polarizers used on lights are heat sensitive. You have to make sure that you don't have them so close to the light source that they begin to deform or warp. They need an airspace.
A good way to determine how much space is with a piece of unexposed but developed black and white film. Just hold it in front of the light and see if it starts to deform, if it does move it a little further away. When you find the spot where it doesn't then that is how far away the polarizers should be from the light.

2: When photographing precious metals under polarized light, silver, gold, platinum, they will appear black so if they are present in the art work or the frame or matte watch out.

3: When setting the lights up the one on the left should point to the right edge of the art work and the one on the right should point to the left edge. This way you will avoid the hot spot in the center that can occur when both lights are directed at the middle of the art work or copy work.

Lastly, since you are not in the USA, you can get sheets of polarizing material up to 40 x 40cm, 0.4mm thick, from Heliopan in Munich. These are not polarizers that you can use on a lens as they are not optical grade. However you would have to make your own holding system.

As someone else suggested, a pair of clips doew work. One easy way to make your own is to make a large hole in a piece of heavy weight, black mount board, tape the polarizing gel to the mount and then mark each mount with an indicator that shows the plane of polarization.

It is easy to determine this by looking through your camera's polarizing filter at one of the lighting pols. Then rotating the lighting polarizer till you get the max. polarizing effect. Then make a mark so you know where that point is and repeat with the other lighting pol. It is important that you do not change the position of the camera pol while doing this.

Then when you are ready to use the pols just mount them to the lights so the index mark that you made is in the same position on each light. It will save a lot of set-up time when you are ready to shoot as all you will have to do is point the lights and then rotate the pol on your lens.

Robert Langham
31-Jan-2013, 15:06
Just in case you were confused by the excellence of my description: Here's a light set up with the cone, clamps and polarizer film:

88358

esox
31-Jan-2013, 16:10
I ws a bit overwhelmed by the excellence of your technical words (excuse my french, I'm ... french...) but I'm completly subjugated by the superiority of your illustration !

Now I have to find 4 identical used studio flashes... That is a challenge ! Is it necessary that they are fully identical or equal power is enough ?

Drew Wiley
31-Jan-2013, 16:45
One thing I don't think anyone brought up yet is the need for a long enough lens to back away from the shot and not accidentally become part of it - what I mean is that some media are reflective enough
that the light will reflect onto you or shiny parts of your gear, and then back onto the subject. In a worst case scenario, you can wear black clothes and tape over the shiny things with black masking tape, or better yet, shoot through a hole in black board, kinda like making a black bird-watching blind.

esox
31-Jan-2013, 17:56
Ilportant detail.
What do you think about continuous light ?

lenser
31-Jan-2013, 18:14
May not be allowed due to heat on the paintings and much harder to do with the highly heat sensitive polarizing gels.

esox
31-Jan-2013, 18:43
Ok. It won.t be museum work. It shooting for painters for their catalog. I will do them with the painters.

Sevo
1-Feb-2013, 00:49
May not be allowed due to heat on the paintings

But that argument goes either way, as curators tend to have the gear to test continuous light for fading and heat risks, while they usually cannot test flash. The more critical museum work I've done had to be done with low intensity (i.e. the focusing light on my flashes) halogen with extra UV filters, the most critical with whatever light the conservator had installed.

esox
1-Feb-2013, 01:43
And if here is no curator involved, just the painter in his their own studio ?

Sevo
1-Feb-2013, 02:45
And if here is no curator involved, just the painter in his their own studio ?

Probably irrelevant, but YMMV, especially with the age of the painter. I've seen a few approaching senility that were disproportionally concerned about their paintings, while the young ones generally are entirely negligent when it comes to their own unsold works - I've seen a now famous and museum-owned painting used as a room separator for a rave party in the artists studio...

esox
1-Feb-2013, 08:29
Isn't it what we can call a "cliché" ? You also have young men disproportionally concerned about theur work and older ones really fine...

Drew Wiley
1-Feb-2013, 10:23
I am no specialist, but have done a quite a bit of work with traditional hotlights. You just keep your gels and polarizing sheets at proper distance with a clip-in frame. And you don't want to book a long
session on a hot day in a small room with hot lights! You shut them off between critical use. But seems to me more straightforward than lugging around a bunch of flash gear, unless you are already
experienced with that sort of thing. A good color temp meter is a wise investment. Halogens can damage a painting, but not in this kind of application unless you're pretty absent-minded. I once had
a bunch of my big Cibachromes featured in a snooty gallery right alonside a buch of Motherwell's big
acrylics. The damn projector halogens were so hot that those old Liquitex acrylics were starting to melt! Given the fact that those paintings were selling around 40K apiece back then (and now for 7 figures), it seemed a little insane. Naturally, I pulled my own prints out of there.

ic-racer
1-Feb-2013, 10:28
The camera will be mfdb phase one on p65+ digital back.

That is a large format camera?

esox
1-Feb-2013, 14:30
Not exactly but the name of the forum is large format photography no ? Not large format camera...

Drew Wiley
1-Feb-2013, 14:35
A semantics misdemeanor. You're contemplating medium format digital work. But the lighting advice
still applies, regardless.

esox
2-Feb-2013, 00:47
Well of course the advices still apply. Will be ignored and thrown away because camera is too small ? :)