Viewing light brightness

[Pieter]

There is a standard for viewing color in the graphic arts industry. It involves an expensive viewing booth (from $500 to well over $10,000 depending on size) with full-spectrum, color-corrected fluorescent tubes and a specific, neutral grey background.

[Drew Wiley]

There is nothing in those viewing booths you cannot set up yourself for a fraction of the price. B&H even sells the official MacBeth gray paint in quarts and gallons. MacBeth 5000K Proof Light tubes can be purchased, or Normlicht. No, you're not going to find anything that accurate in a home center or even typical lighting store. But this kind of thing is relative to pre-press and lab work standardization. To match specific display conditions you have to know what those are. But given the fact they vary widely, I generally try to aim for a midpoint between diffuse daylight and warmer artificial lighting, namely, around 4000K for the final prints. Any intermediate steps COLOR printing, or when spotting final b&w prints, I use precise 5000K true CRI 98 official color matching bulbs. The trickiest thing is a light box. You have to offset the color shift from the diffuser and glass with a special internal paint, or buy a very high quality light box engineered in this manner to begin with. If you're just sorting out negatives and chromes, and inspecting them with a loupe, you can be a lot more casual. But for critical comparisons or backlit color duplication work, it helps to have the real deal.

[Pieter]

There is nothing in those viewing booths you cannot set up yourself for a fraction of the price. B&H even sells the official MacBeth gray paint in quarts and gallons. MacBeth 5000K Proof Light tubes can be purchased, or Normlicht. No, you're not going to find anything that accurate in a home center or even typical lighting store. But this kind of thing is relative to pre-press and lab work standardization. To match specific display conditions you have to know what those are. But given the fact they vary widely, I generally try to aim for a midpoint between diffuse daylight and warmer artificial lighting, namely, around 4000K for the final prints. Any intermediate steps COLOR printing, or when spotting final b&w prints, I use precise 5000K true CRI 98 official color matching bulbs. The trickiest thing is a light box. You have to offset the color shift from the diffuser and glass with a special internal paint, or buy a very high quality light box engineered in this manner to begin with. If you're just sorting out negatives and chromes, and inspecting them with a loupe, you can be a lot more casual. But for critical comparisons or backlit color duplication work, it helps to have the real deal.

Try this for fun: https://www.xrite.com/hue-test

[John Layton]

I recently installed a four foot track light strip over the viewing end of my sink - with two 3500K dimmable LED spots (same as in my gallery) with under sink mounted switch and rheostat. What seems to work for me is to take a white card reading of the lighting at the prints future location (gallery or wherever), and duplicate this by adjusting the darkroom viewing LED's to match the earlier reading, again using a white card at the print viewing plane...then possibly add just a bit of extra light (the amount depending on the paper I'll be using) to account for any possible dry down.

[Michael E]

You have given many helpful hints, but the description of your viewing lights' brightness has been less than scientific :-) I'm sure that some of you own incident light meters. Let's meter and compare, maybe we discover a consensus that can help setting up a darkroom in the future. I adjusted my viewing light to EV 8.3 at the fixer tray location, which converts to rougly 75 ftc or 800 lux, though not tested sufficiently yet. How bright is yours?

[Drew Wiley]

Cute. What's your color IQ? If you even try to take that test using web color samples, you automatically flunk. I had use of an X-Rite spectrophotometers costing $20,000. In Biotech, my wife used a custom X-Rite spectrophotometer that cost 6 million dollars (including secret software). Her little personal quality-control lab had a timed bank vault door on it and concrete walls four feet thick. No person in the company, other than the two owners, was allowed to know more than a small portion of the formula.

[Bob Salomon]

Cute. What's your color IQ? If you even try to take that test using web color samples, you automatically flunk. I had use of an X-Rite spectrophotometers costing $20,000. In Biotech, my wife used a custom X-Rite spectrophotometer that cost 6 million dollars (including secret software). Her little personal quality-control lab had a timed bank vault door on it and concrete walls four feet thick. No person in the company, other than the two owners, was allowed to know more than a small portion of the formula.

Sounds like Coca Cola!

[Drew Wiley]

Bob - on our honeymoon, my wife and I were in a 3-seat row on a plane headed to Kaui next to a gal who was a Coca Cola executive. My wife asked her is she got her Cola free. She replied that she never drank the stuff because every ingredient in it is shipped to the plant DOT Hazardous. But when my wife worked in Biotech six years somewhat later, she was in charge of quality control of designer vaccine samples, etc that averaged $40,000 per cc. This was done under contract for the high rollers like Bayer and Genentech who could afford the billions of dollars per new drug necessary to scale up production and get things through FDA. Back then the equivalent of a gallon of an actual pharmaceutical product at Bayer was often worth 2 million dollars. The clean room control was (and presumably still is) tyrannical.

[Bob Salomon]

Bob - on our honeymoon, my wife and I were in a 3-seat row on a plane headed to Kaui next to a gal who was a Coca Cola executive. My wife asked her is she got her Cola free. She replied that she never drank the stuff because every ingredient in it is shipped to the plant DOT Hazardous. But when my wife worked in Biotech six years somewhat later, she was in charge of quality control of designer vaccine samples, etc that averaged $40,000 per cc. This was done under contract for the high rollers like Bayer and Genentech who could afford the billions of dollars per new drug necessary to scale up production and get things through FDA. Back then the equivalent of a gallon of an actual pharmaceutical product at Bayer was often worth 2 million dollars. The clean room control was (and presumably still is) tyrannical.

My wife and I, as well as my daughter, son and son in law all went to Emory, known as the Coca Cola school from the support from Coke.
I was the house manager of our fraternity where we had a soda machine, $0.5 per bottle. But it was not a coke machine.
One day two guys drove up in a Coke truck, in Coke uniforms, wheeling in a Coke vending machine.
We had never ordered it but they took our machine, left theirs, full of Coke.

[Drew Wiley]

Getting back on topic, I used a fancy XRite spectrophotometer to batch up my own gray paint, precisely neutral not only over the entire visible spectrum, but a step into UV and IR too. You can't walk into a paint store and ask for something like that. Typically it takes a standard factory-made batch of at least 144 gallons; and in the case of MacBeth, I'm sure the exact formula is proprietary, and then cross-checked afterwards. I made mine on a rainy day jockeying back and forth, in instances just dipping the point of a pencil into this or that pigment to ever so slightly tweak the outcome. Not that I really needed something that precise - more of just a challenge.