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Use light meter to test studio brightness?

I was intrigued with Mark's discussion regarding museum lighting and how the best paintings without the proper lighting might otherwise appear dark. Then it occurred to me that if we paint in a studio with not enough lighting, we might tend to make our paintings a bit lighter than ideal, whereupon in quality museum lighting, they would appear to be 'washed out".   I think.

Anyway, about half a dozen 1600 lumen bulbs at about 8 feet at 35 degrees might be the 'right' lighting. I was wondering if we could use a camera meter taken off a toned canvas to determine a proper lighting brightness?

Comments

  • Wait for @Dencal Denis to weigh in on the high tech stuff but that "museum Quality" lighting thing is an on-going discussion Mainly because most of us realize our paintings are not going to be displayed with museum lighting.
  • Folks



    Your combo of 6x1600 at 8 feet results in a miserable 128 lux.


       
    If you boost the lumens to 40000 and reduce the spherical radius to 6 feet you can achieve around 950 lux.



    Denis

  • Yeah, what he said.
  • Or... get two 85W CFL bulbs with a 5000 (4800-5200) color temperature. Place one over each shoulder 35degrees from eyelevel on the canvas.
  • Bob

    That will produce about 150 lux. Pretty dim for painting and value discrimination.

    Denis

  • I have white walls and am tempted to wear sunglasses when they're both on. These are big curly lights that don't fit in anything but a socket with out any diffuser.
  • You will quickly learn through experience what your paintings and values look like in different lighting conditions, and then you can use this knowledge to determine how you paint and whether or not you need to change your lighting setup. I use 2x of those 150watt spiral bulbs mark recommends and it is nice and bright. A couple of my paintings are too dark in normal indoor lighting so now I know I have to have them brighter than that.
  • Unfortunately that is the only way to tell if it works.

  • Thank you for the replies. I got lost in all that 'technical stuff' in the lumens to lux post,  but I do appreciate the information, and I will seriously look into it and try to grasp it some time.

    But I did have an idea. I looked at some photos I took of paintings a top gallery owner graciously allowed me to take a few years back. I looked up the file info in PhotoShop of those photos to see what exposures I made with my DSLR.

    The results were I got for ISO  500 exposures  ranged from 1/30 to 1/50th of a second at 5.6. Being a very good gallery with beautiful paintings, I figure their lighting was dead on. This I think can serve a basis to answer my original proposal here.

    So I just checked my lighting situation for a 'primed' canvas on my easel with my own, albeit basic, one bulb 1600 lumen lighting 5000 K LED at about 3.5 feet at approximately 35 degrees overhead and behind (obviously not a recommended distance!). Spot metering on the canvas, I got just that as the gallery, 1/50 sec at f5.6 ISO 500 at the top of the 'grayed' canvas. So my brightness of my own studio set up was mostly about right anyway. Interestingly however and taking a hint from MC, I decided to also spot meter the bottom part of the canvas. And it measured only 1/30 sec at f5.6 Iso 500- about a 2/3 f stop decrease in light!

    Thus I see the valuable point of adding more distance between your light source and your working canvas so as to even out the light, top to bottom. And this would obviously entail for me to get at least one more light and place them both farther back. Cool stuff to know and think about!
  • MillerLandscapes

    Here is a formula to convert camera readings to an approximation of lux.

    Lux = 50 x fnumber2/ (exposure time in seconds x ISO film speed)

    http://www.conservationphysics.org/lightmtr/luxmtr1.php


    Denis


  • lol, But actually not so scary. I did look into that link and gleaned some valuable information right away. And one of the most salient points worthy to know I think is that the degree of incident light (lux), or ambient light, falling on a subject is entirely different from the light being reflected off the subject. Gets you to thinking critically about lighting, which is helpful.
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