cross-polarization to eliminate glare in photos of paintings

Okay, so I have too much work to focus on to experiment with this yet, so I thought I might outsource this to anyone interested who:

1) takes photos of their paintings often enough for this to be worthwhile to them, and

2) has a good handle on photography already and a decent camera.

Basically, I take decent photos of paintings with some caveats. For one thing, they're high-res but not super high-res, on account of not having a medium-format (or even a full-frame) camera. But that's not really an issue for us since the resolution we get is good enough for the web and then some.

But glare! Ugh! We really don't have a good solution for that. I don't mean the easily avoidable glare, but rather the little spots and streaks of glare where the brushstrokes left some texture in the paint. It's a big hassle for us, leaving us with images that aren't as good as they could be and creating work for us (getting rid of especially bad glare spots manually in Photoshop, altering perspective in Photoshop due to the slight angle I take photos at to minimize glare, etc).

So check this out: jmahorney.blogspot.com/2010/08/where-you-been-or-death-to-glare.html

If anyone wants to try that out properly and carefully and post their results, that would be awesome, but I'll try it eventually so only do it if you need to be able to take good photos of your work anyway. I'm sure it works to get rid of glare, but I want to try to find any problems this method creates before recommending it… and before telling Mark we need to buy new equipment!
Castillo

Comments

  • David

    This link examines polarization in artwork photography.

    He is not finished but presents some interesting points:

    http://www.betterlight.com/downloads/conference10_speakers/guyer_Polarization.pdf

    Denis

    Castillo
  • When I had one I didn't get a chance to experiment photographing paintings. I do remember @jcdr mentioned he experienced the same results of increased saturation and contrast.

    Here's a video showing the effects of polarized light
    dencal
  • I talked to my eye doctor about polarizing lenses for night vision, specifically to reduce glare when driving at night -- especially in the rain. He pointed out that true polarizing filters cut 50% of the light, so he didn't recommend them for night driving because there's too little light already. Does anybody know how to compensate for the loss of light when using polarizing filters for photography? Will TTL metering sort of take care of that magically? Cross polarization will reduce the light by 75%, if my math is correct.
  • rgr
    Will TTL metering sort of take care of that magically?
    Yes. TTL will make the necessary exposure adjustment.

    Denis


  • Which camera do you guys use, David?
  • @savignano‌ We use three Panasonic GH3s, which we got primarily for video purposes (otherwise we would have gotten an Olympus E-M10 I think). There is a nice lens option for the camera but due to our budget we're using a less-than-ideal lens which is kind of a pain, especially for filming.

    If finances allow I would like to get a GH4 for myself in the future, or possibly even a bunch of them for DMP filming — it'd be nice to have 5 or 6, although then we'd probably need to get more serious about our storage and hard-drive I/O setup, which costs time and money too.

    The GH4 lets you adjust the particulars of the tone curve, so I think I would be able to calibrate it to film more true-to-life footage than we can with the GH3. There are other nice features as well, including the ability to refocus with focus assistance without stopping the recording.

    I imagine the still-image performance is virtually identical, though. Since stills are shot in RAW, I should be able to calibrate a tone-curve preset to apply in post. The bottleneck there is simply not having the time at the moment!
  • charischaris -
    edited May 2014
    We use cross polarization now that I've started varnishing my paintings. (Had a heck of a time eliminating the glare from all the dust that always manages to find its way into the varnish as it is drying.)

    We have a good digital camera (not pro full frame, but very good), a well made polarizing filter, and two sheets of polarizing film we purchased from B&H Photo. (It isn't cheap but sure has made the difference.)

    Our two lights (daylight bulbs), with the polarizing sheets in front of them, sit at 45 degree angles from the painting on either side and BEHIND our camera.

    Our exposures are quite long, so we use a remote shutter trigger and make sure the viewfinder is covered to keep light from entering the camera from the back.

    I'll have to check my other computer to see if i saved any of the glare-laden photos for a 'before' example, but you can check out the photos we do now on my website chariscongail.com

    Really works for us so far.

    c
    [Deleted User]Castillo
  • @charis I love your website, love your paintings, and really appreciate the info! Have you encountered any unwanted side-effects from the cross-polarizing? If not, this is definitely the way to go!
  • @david hi David! and thank you.

    I've heard that the method creates unwanted contrast, and that it results in too dark an image, but have encountered neither issue. At this point, I can't say anything bad about it.

    We bracket our (usually long) exposures and I will still do a little cleaning in photoshop...

    The photos are taken at night in an otherwise dark room -- just the daylight bulbs at 45's with no other light that might create glare or other uncontrolled artifacts.

    I like the look of the canvas tooth coming through, but some people might want to adjust the lights/filters/photoshop adjustments just a little more to get rid of that.

    Our filters are from a Rosco 17x20 Polarizing filter that we cut in half. We don't have the budget for a nice barn door setup so i leave the sheets a little curved when i tape them onto a piece of cardboard that has had a circle cut out of the middle, and clamp them to a light stand in front of the daylight bulbs. (We are sooooo high tech!)

    Castillo
  • @David_Quinn_Carder‌ and @charis‌, the only issue I keep reading about which is also mentioned in the link posted by @dencal‌ is that it does not play well with metallic surfaces(see samples below).

    image
    image
    image

    which tells me that Klimt would have been very unhappy with the results

    image
    charisebs
  • @charis Had a look at your website. Your work is fantastic! I feel really inspired by looking at your paintings. Do you use Mark's limited palette?
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