Topic: Lighting for copying artwork (Read 9852 times)

scott morrish · « **on:** February 08, 2012, 12:42:57 pm »

I am looking to buy lighting specifically for a permanent 'copy' set up.
Whilst i'd like it to use as little power as possible - my primary objective is to minimise time spent colour-matching.
To this end... what are the best lights to use?

Thanks for any advice...
scott

Brian Hirschfeld · « **Reply #1 on:** February 08, 2012, 01:43:50 pm »

I helped a very successful artist friend of my family make a system using large 4x6 profoto soft boxes and an acute2r 2400 system which worked pretty good, If I was going to do it again, i would recommend hot lights, since it seems more artists use that. Profoto offers continuous lighting systems for cinema, which are compatible with all of their light modifiers. You want to make sure you either have a VERY consistent color temperature so that you can correct for it in camera with the custom white balance setting, or not need to. A color checker of some sort would be ideal, so that you can have a pre-set on your computer to allow you to correct it in one click. A sturdy tripod, cable release, and mirror up mode wouldn't hurt either. Using a f/8-f/11 aperture will allow you to achieve maximum image quality with most lenses too, which helps get detail, but sometimes this may be too much if you are shooting a canvas, so you might want to use smaller to make it softer, and smooth things out.

scott morrish · « **Reply #2 on:** February 08, 2012, 03:52:23 pm »

Thanks for this: I'll talk to ProPhoto.
I was thinking some kind of strip-lighting for even lighting rather than soft boxes. Is there anything like that that offers colour quality / consistency?
Regards,
Scott

Brian Hirschfeld · « **Reply #3 on:** February 08, 2012, 04:07:15 pm »

Well again, using strobes, or hot lights which have a strobe modifier mounting system (I know there are others, but I am most familiar with profoto) you have the option to use any light modifier(s) you want, so thats possible, strip lights offer more directed light, so it would be harder to balance them especially in the middle, because at closer distances small differences will be noticeable...thats Why I would recommend larger soft boxes or possibly shoot through umbrellas because it will diffuse and spread the light nicely and not to mention easily.

Profoto offers tungsten and daylight balanced models of their continuous lights http://www.profoto.com/products/continuous-light either would work fine, its good because u know what your getting in terms of wb...

also a tilt shift lens is what we used, the rational behind this was, since the pieces of art were large, and stood up against a wall, it could help to flatten them out and remove anything like a keystone effect or change in perspective in the final image because of it leaning against the wall. Of course this could be adjusted later in Photoshop or C1 or whatever, but that adds steps and causes a loss of data.

LKaven · « **Reply #4 on:** February 08, 2012, 05:30:11 pm »

Recommend two flanking strobes angled in at 45 degrees, each with Rosco polarizing gels oriented at right angles with respect to one another. Use a circular polarizer on your lens and adjust until glare off the canvas disappears. No diffusion used in this setup.

Otherwise, you will get copious glare off the highlights in any work that has texture, e.g., a painting.

Brian Hirschfeld · « **Reply #5 on:** February 08, 2012, 05:30:50 pm »

Thank you for mentioning that, I forgot that part, the polarizers are important.

BobDavid · « **Reply #6 on:** February 09, 2012, 09:07:12 am »

You do not want to put polarizers over soft boxes. Use modifiers that do not diffuse the light.

bjanes · « **Reply #7 on:** February 09, 2012, 10:29:45 am »

Quote from: LKaven on February 08, 2012, 05:30:11 pm

Recommend two flanking strobes angled in at 45 degrees, each with Rosco polarizing gels oriented at right angles with respect to one another. Use a circular polarizer on your lens and adjust until glare off the canvas disappears. No diffusion used in this setup.

Otherwise, you will get copious glare off the highlights in any work that has texture, e.g., a painting.

An excellent suggestion. If you can't get uniform lighting with such a setup, you might try using a flat field calibration. The topic is discussed by Martin Evening in a post covering removing of sensor marks and lens vignetting, but the same technique can be used for non-uniform lighting.

The attached examples show the use of this technique in photomicroscopy.

Regards,

Bill

Doug Peterson · « **Reply #8 on:** February 09, 2012, 10:42:16 am »

The Flat Field stuff is built in to Capture One Pro (as well as a handful of other programs). It's called "LCC" in Capture One and can be used in art repro by photographing a white "reference" paper placed on top of the artwork (once at the beginning of the shoot) and applied to the capture of the artwork - it takes less than a minute, is super easy, and will remove dust from the sensor, color differences (e.g. if the two heads are 200k apart in WB), and fall off. It's also applied in real time as you shoot tethered (as an adjustment sidecar to the raw file - no permanent change to the raw file in case you want to redo/undo it).

There is some great info out there about the underlying technology of LCC / Flat Field Correction (also called other things in other programs). But for most users you don't need to understand the science behind it - just shoot a white paper and tell the software to use that to correct the images of the art.

If this is serious art repro you are doing I'd strongly suggest contacting someone (e.g. us or another value added dealer) to talk about actual copy stands. A good copy stand will make sure the camera is perpendicular to the artwork, the lighting is at precise and equal angles and heights, integrate the lights into the chassis of the stand so that you don't have to set up / tear down / tweak every time, and generally make life easier for doing art reproduction.

I'd suggest two decent heads (Profoto Acute was a good suggestion, Broncolor Senso would be another) that are known/reliable for consistent color and exposure and being generally fuss-free/dependable. Talk to a dealer, user, or read the manual so you know the various settings to use on the strobe to insure the very best color accuracy (e.g. on a Profoto Acute you want to keep the (-2 to 0) knob at 0 and vary the power only using the (1/4, 1/2, 1/1) switches if color accuracy is a top priority.

If it's an occasional and informal thing then just get any old lights, mount them 45 deg and equidistant from the artwork with either hard modifiers with polarizers or soft modifiers without polarizers.

Art repro is definitely one of those areas where there is a huge difference in cost between wanting to get "pretty good results with modest effort" vs. "getting great results very easily". You have to decide early on which of those two describes your needs better (neither would make you a better or worse person - it depends on your needs - what you need the art repro for).

Bias note: we sell everything we're describing and have done a lot of work with art repro clients setting up art repro solutions.

Doug Peterson (e-mail Me)
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Ben Rubinstein · « **Reply #9 on:** February 09, 2012, 10:55:15 am »

Yup, we're intending to do just that for photographing manuscripts.

bjanes · « **Reply #10 on:** February 09, 2012, 11:20:42 am »

Quote from: dougpetersonci on February 09, 2012, 10:42:16 am

The Flat Field correction is built in to Capture One Pro.

Thanks for pointing that out, Doug. I wasn't aware that Capture One had that ability, since I have been using Camera Raw + Photoshop for my work. Certainly, Capture One is worth a look for those doing scientific and fine art reproduction photography. Also, the ability of Capture One to use ICC profiles might also be of some use in getting more accurate color reproduction. While some have been getting good results with ACR and Passport or the DNG Profile Editor using the MacBeth (x-rite) Colorchecker, using more patches with a ColorcheckerDC might give better results.

Regards,

Bill

(Revised at Doug's suggestion)

Doug Peterson · « **Reply #11 on:** February 09, 2012, 11:55:24 am »

No denigration intended. "Mumbo jumbo" was to imply the full technical explanation of what is going on during flat field correction can be relatively involved but that the user need not worry or be intimidated by the full technical underpinnings - they can use simply do the correction and it "just works".

Certainly for those who are scientifically/mathematically curious (for the sake of the curiosity itself) or who are very detail oriented a complete understanding (as much of it as can be found in public documentation) is certainly very interesting.

To be clear I have no experience with the software you linked towards and did not mean anything positive or negative towards it. My apologies for using phrasing which was not clear in that regard. "mumbo jumbo" probably wasn't the right phrase. I can see where you interpreted it the way you did. Perhaps "stuff" would have read better.

I've modified my original post accordingly.

Though I would politely add that it would have felt nice to be given the benefit of the doubt for the sake of friendliness. Perhaps you might have said instead "Did you intend to denigrate this product? That's how it reads to me and that would be inappropriate."

LKaven · « **Reply #12 on:** February 09, 2012, 02:22:45 pm »

John -- so much good information in there. Worth bookmarking, to say the least. Thanks very much!

Stefan.Steib · « **Reply #13 on:** February 09, 2012, 04:56:38 pm »

John

Thanks for that Info about the aging PL´s- this was even new to me ! (and I also have done _some_ repros in my life !)

Regards
Stefan

bjanes · « **Reply #14 on:** February 09, 2012, 05:29:39 pm »

Quote from: dougpetersonci on February 09, 2012, 11:55:24 am

I've modified my original post accordingly.

In the interest of good forum etiquette, I have done the same.

Regards,

Bill

LKaven · « **Reply #15 on:** February 09, 2012, 06:19:17 pm »

John you reminded me that I copied some paintings for a painter who did some of his work on sheet metal. The glare was a part of the entire experience.

What are some of the other situations in which you would recommend against using cross-polarization? I wonder, for example, whether some of the traditional pigments depending upon a certain spectral "glint" that falls flat under polarization? I have noticed some color shifts on a few oil paintings, and wondered what the cause was. By contrast, I would expect most acrylics to do rather well. What does your experience tell you?

Doug Peterson · « **Reply #16 on:** February 09, 2012, 06:44:40 pm »

Quote from: bjanes on February 09, 2012, 11:20:42 am

Also, the ability of Capture One to use ICC profiles might also be of some use in getting more accurate color reproduction. While some have been getting good results with ACR and Passport or the DNG Profile Editor using the MacBeth (x-rite) Colorchecker, using more patches with a ColorcheckerDC might give better results.

If you're going to be spending a lot of time doing this it's probably worth testing and comparing both those methods to see what gets you closest to where you want to be. Both have advantages/disadvantages.

MichaelEzra · « **Reply #17 on:** February 09, 2012, 09:16:34 pm »

Quote from: scott morrish on February 08, 2012, 12:42:57 pm

I am looking to buy lighting specifically for a permanent 'copy' set up.
Whilst i'd like it to use as little power as possible - my primary objective is to minimise time spent colour-matching.
To this end... what are the best lights to use?

Thanks for any advice...
scott

Scott, I would recommend to look at Solux lighting for art reproduction: http://www.solux.net/cgi-bin/tlistore/infopages/index.html
This may turn out to be the least expensive yet the most accurate solution.
You may also consider open source (free) RawTherapee 4.0.7 that offers Flat Field correction ((illustrated in the manual, page 36) and an option to provide camera input icc profiles for accurate color matching.

scott morrish · « **Reply #18 on:** February 10, 2012, 09:36:24 am »

Quote from: MichaelEzra on February 09, 2012, 09:16:34 pm

Scott, I would recommend to look at Solux lighting for art reproduction: http://www.solux.net/cgi-bin/tlistore/infopages/index.html
This may turn out to be the least expensive yet the most accurate solution.

Thanks to everyone that has responded here... really helpful... and much appreciated.
Michael's comment above has made me wonder: Is there an obvious right or wrong with regards to D50 v's D65 for this type of work?

Scott

BillOConnor · « **Reply #19 on:** February 11, 2012, 11:13:50 pm »

Correction, the polarizers on the lights should be parallel to each other, if you put them that right angles to each other, one side of the painting will not be polarized.
Also the two lights at 45 degree angles, polarized, pol filter on lens works for many things, especially flat 2D works, but an oil painting is a 3D object. There are many, many other ways to light oil paintings.

Bill

Author Topic: Lighting for copying artwork (Read 9852 times)