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Author Topic: Digital darkroom lighting  (Read 5484 times)

scubarob639

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Digital darkroom lighting
« on: September 12, 2009, 09:02:43 pm »

I'm redoing my office and want to install the correct light temp. for processing and printing.  Solux makes 3500,4700,5000K lights.  They suggest using the 4700K for processing,profiling.  and use the 3500K for viewing the work.  Why do they use two different temps? Can I process my own work and view it using all 3500K lamps?  Any suggestions would be appreciated. I have been calibrating my monitor to 6500K 2.2 Gamma.

Thanks,   Rob
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Mark D Segal

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Digital darkroom lighting
« Reply #1 on: September 13, 2009, 12:10:00 am »

3500 is closer to the temperature under which most work would be viewed outside your digital darkroom. Regular halogen bulbs for example would be close to this temperature, and incandescent lamps warmer still. Solux 4700 corresponds more closely with mid-day daylight hence it is recommended to see colours correctly. There really is a large disconnect of colour temperature between 6500 and 3500. It would make me nervous. The prints would appear systematically warmer than the images would look on the display when the two are compared side-by-side. You'd probably have less grief more closely alligning the display temperature with the Solux 4700 temperature (say setting the display in the range of 5000-5500) and forget about the 3500 idea. People looking at the prints under 3500 without a comparator wouldn't perceive the difference, because human visual perception adapts to different "shades of white". We're pretty good at seeing RELATIVE differences (when there is a comparator) but not very good at ABSOLUTE differences (no comparator), and this provides quite a bit of flex for viewing conditions. When you work on the images, you're engaged in RELATIVE perception, so you don't want a set-up that will drive you nuts.
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Mark D Segal (formerly MarkDS)
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jvora

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Digital darkroom lighting
« Reply #2 on: September 13, 2009, 12:38:14 am »

Hello Rob :

I took noted this approx 3 years ago - Unfortunately, I no longer have a link to the site it's from - See if this helps :

"Digital Darkroon ISO Standard

      Light table for viewing slides.
     5000K
     Ra >96
     Intensity= 1400 Candela/m2.
     This equals a reflected reading of 1/60 sec and f.11 at 100 ISO

     Lights for viewing prints.
     5000K
     Ra >96
     1500-2500 lux at the print.
     Take a reflected reading from a white paper and it should say 1/30 sec, f.11 at 100 ISO

     Room light.
     32 lux in the room. Put a white paper at the screen (turn the screen of) and take you know what              
     that should read 1/4 sec,  f.4 at 100 ISO

     Use tubes that is 5000 K and Ra >96 in the ceiling.

     Paint the walls gray so they equal zone VII (two stops more than Kodak’s graycard).

     The screen.
     If you are producing a digital original (you are not going to compare it with a print) it should be set
     at 6500 K.  If you are comparing the screen image with a print it should be set at 5000K.

     Gamma?
     It doesn’t say because the gamma you are using at your screen is included in the ICC-profile.
     But for web you should use 2.2 if it is intended to be viewed in Windows and 1.8 for Mac.

     The white of the screen should be 80-120 Candela/m2. Use a calculator to find out what that should be in
     f-stops.

     I made a mistake regarding light tables. It should be 1/60 and f.11.

     ISO will recommend 5000 K för the screen when comparing to a print, but as arodney says, most profesionals
     think that  gives a yellow screen with not enough contrast.  On a good screen 5500-6000 normally gives the
     best result when you compare a white paper to the white of the screen. Assuming of course that you are using
     correct 5000 K light in the room."




Quote from: scubarob639
I'm redoing my office and want to install the correct light temp. for processing and printing.  Solux makes 3500,4700,5000K lights.  They suggest using the 4700K for processing,profiling.  and use the 3500K for viewing the work.  Why do they use two different temps? Can I process my own work and view it using all 3500K lamps?  Any suggestions would be appreciated. I have been calibrating my monitor to 6500K 2.2 Gamma.

Thanks,   Rob
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Pat Herold

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Digital darkroom lighting
« Reply #3 on: September 14, 2009, 07:32:51 pm »

Go with the recommendation by Solux.  You will find strangely enough that the white of your monitor calibrated to 6500 K will match pretty closely to a blank page of your printer paper illuminated by the 4700 K lamps by Solux.  Getting your whites to match is really what should be driving this decision, because monitor and printer profiles are scaled to their respective whites.  If the white's don't match, the rest of an image will look off too.

http://www.colorwiki.com/wiki/Printer_to_M...Screen#LIGHTING
« Last Edit: September 14, 2009, 07:34:53 pm by pherold »
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peteh

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« Reply #4 on: September 14, 2009, 07:58:09 pm »

Quote from: pherold
Go with the recommendation by Solux.  You will find strangely enough that the white of your monitor calibrated to 6500 K will match pretty closely to a blank page of your printer paper illuminated by the 4700 K lamps by Solux.  Getting your whites to match is really what should be driving this decision, because monitor and printer profiles are scaled to their respective whites.  If the white's don't match, the rest of an image will look off too.

http://www.colorwiki.com/wiki/Printer_to_M...Screen#LIGHTING
I use 4700 K Solux and no problems. Paul Caponigro likes 3500 K because thats what temp. his prints are viewed at in galleries.
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Mark D Segal

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« Reply #5 on: September 14, 2009, 11:31:12 pm »

I use Solux bulbs also. And strangely enough for a lot of colour work, keeping the display at 6500 can work not too badly.  Where it falls apart, however, is when you produce tinted B&W prints. You will likely notice, when viewed under 4700K, and worse still under 3500K, that they are too warm relative to what you thought you would get when you adjusted them on a display at 6500K. So for this kind of work, you would want a warmer display, in order to not be misled about the appearance of the tint under warmer illumination. Perhaps this is why JPC uses 3500. Like so much else in this field, their "ain't" one simple right answer.
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Mark D Segal (formerly MarkDS)
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