Viewing light brightness

[Michael E]

Hello everyone,

I just finished my new darkroom and have a question about your experience with the viewing light: You know, the light fixture over your fixer tray that lets you judge your test strip or final print without surprises later. I went all over board and got a dimmable 5600K LED strip, but now I have to set it at the best level. There must be a golden and measurable standard, right? All I found was "The New Darkroom Handbook" quoting Kodak at 50 footcandle for color work, and they recommend 80 - 100 footcandle to match gallery light. ISO 3664:2009 specifies 2000 Lux for the viewing of prints, which seems a lot to me. How did you figure out what worked best for you? I know the brightness depends on the conditions of the final presentation of the print, so what did you choose as your comparison?

Curious,

Michael

[Drew Wiley]

You need to view your work in more than one option with respect to both color temperature and brightness. That 5600K light will probably not actually be 5600 K anyway. You'd need to check it with a color temp meter. Some have adjustable color temp. I use 4000K as a nice midway point between daylight and residential tungsten light, as well as having on hand critical 5000K lights, and then a selection of other lights in another room. Then I'll take a print or test strip outdoors and check it there. At one time I also had a test gallery wall in my studio. Use common sense. Galleries are not standardized, and residences certainly aren't either. You need to view test strips dry anyway. When in doubt, I put them in a little toaster oven for about 20 sec. Then toning becomes a factor. With experience, it all gets easier.

[LabRat]

I backed off the brightness, as my eyes were dark adapted, and the 250w flood was too much...

I had a footswitch on it but had to be careful where it was as I could possibly trip or press it at the wrong time during the process, so I found a place behind a sink table leg for it...

I found just bright enough where I got a good white light was fine, and mostly used to check for possible stains on whites...

I never trust a wet print for image or density, as this changes so much when truly dry...

Steve K

[Maris Rusis]

I use a tungsten filament inspection light, 20W Pearl, ceiling mounted that gives me 40 lux at the fixer tray. This is too dim to judge fine detail but the tones seen this way are near to what the wet print will dry-down to eventually. If the inspection light is too bright the wet print in the fixer tray will look beautiful but the final dry down result will be too dark. Final inspection of dry prints is done at 400 lux. I never change these light levels. It seems to help the eye retain its calibration.

As for gallery lighting, it's all over the place. I've measured a yellow tungsten 50 lux in the state gallery and 650 lux daylight fluorescent in a commercial gallery. There's no way to allow for all that unless you know in advance.

[Bob Salomon]

I use a tungsten filament inspection light, 20W Pearl, ceiling mounted that gives me 40 lux at the fixer tray. This is too dim to judge fine detail but the tones seen this way are near to what the wet print will dry-down to eventually. If the inspection light is too bright the wet print in the fixer tray will look beautiful but the final dry down result will be too dark. Final inspection of dry prints is done at 400 lux. I never change these light levels. It seems to help the eye retain its calibration.

As for gallery lighting, it's all over the place. I've measured a yellow tungsten 50 lux in the state gallery and 650 lux daylight fluorescent in a commercial gallery. There's no way to allow for all that unless you know in advance.

That gallery exhibiting color prints with fluorescents?

[Michael E]

I never trust a wet print for image or density, as this changes so much when truly dry...



I don't dry every test strip right away. Or print for that matter. Fix them, wash them, dry them over night. Of course they change a bit, but I've been doing this long enough to take that into consideration. While my darkroom was a construction site, I did a few 8x10" contacts in my bathroom, and they all turned out dark and dull because of the bathroom light. So I want to put in some effort and set up a good viewing light in the new darkroom. I often print at nighttime, so I can't just go outside to check.

[Drew Wiley]

Bob - I once pulled a bunch of my color prints out of one of the most expensive galleries in SF. They had the damn projector halogens so hot that they were starting to melt the acrylic pigments on adjacent paintings by a major abstract expressionist. I've seen it all.
Never assume someone knows what they are doing.

[Jim Noel]

SOmewhere in the many books I have there is a recommendation as to the best amount of light for this purpose. I use a 50 watt bulb at between 3 and 4 feet. Brighter bulbs result in prints being too dark when viewed in normal room light.

[Ken Lee]

I've had the same experience: there's no standard enforced and few people are well-informed about lighting intensity and color.

I've visited and shown my work in galleries where the actual lighting hardware varied within the same room and mixed with window lighting.

Once the work goes to someone's home or office or business, all bets are off about how they light it... if they do at all.

[Vaughn]

My only suggestion is that when one turns on the viewing light, give yourself a few seconds for one's eyes to adjust to it before looking at one's print. I find that my first impression of the print/image when seen with dilated eyes and lots of light tends to bias me towards a darker print.

[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.

[Bob Salomon]

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.

Kaiser Fototechnik Pro lightboxes used 5000k tubes but a custom formulated proprietary paint for the reflector surfaces that compensated for the spikes and dips in the tubes AND the diffuser.

[Drew Wiley]

Yes, that's what needs to be done. I had to batch up my own special liner white paint to do that. Nothing is trickier than "white". You also have to understand how specific white pigments age.

[Bob Salomon]

Yes, that's what needs to be done. I had to batch up my own special liner white paint to do that. Nothing is trickier than "white". You also have to understand how specific white pigments age.

There was a little more to it then just special paint. Their boxes were pretty thin so the tubes were very close to the diffuser. So besides 5000K tubes each tube had a 5mm silver stripe down the length of them that was opaque and eliminated a hot stripe the length of the tube when looking down onto the diffuser. Tubes were also extremely high CRI as well.

[Drew Wiley]

Yeah, avoiding hot spots in thin boxes is difficult. My own critical light box is sometimes used for backlit copy work (LF chromes), so needs to be completely even.

[LabRat]

Back to the light over the fixer tray, as I said I look for stains + uneven development, will the whites separate and leave a line between whites and border, and no Dmax in the blacks as the print will be drying down...

The color correction is not critical for B/W as long as the whites are fairly neutral to spot stains etc, but maybe for toning... Color viewing is a whole different matter and much more critical... For B/W, just a light bulb has worked for many for the post electricity period. .. ;-)

Steve K

[Drew Wiley]

The problem with b&w evaluation, at least in my case, is the fact that a degree of color (warmness/coolness) is integral to the process, and I am very particular about that with respect to specific images. Then there is the effect of toners, and potentially of split toning. A poor viewing light (like nearly all CFL's) can lead to misjudgment from metamerism. A basic tungsten bulb has a continuous "black body" spectrum without a bunch of spikes and voids to it, so works better. But I never really know for certain until I re-evaluate a complete dry print the following day, when my eyes are fresh (and NEVER after doing something like I am at the moment, looking at a computer screen). Now for some hypocrisy ... I gotta go do a test strip, then a big color print.

[Bob Salomon]

Yeah, avoiding hot spots in thin boxes is difficult. My own critical light box is sometimes used for backlit copy work (LF chromes), so needs to be completely even.

I sold Linhof cameras and matched, at the factory, Rodenstock lenses=a lot of both! To what was called a super studio. The studio was owned by a major department store chain in the mid west shooting color catalog shots by multiple photographers all day long, 6 days a week on 45 chromes. Every shooting position had to have matched lenses, lights, light boxes to every other shooting position so that all chromes matched in color as one page might be shot by several photographers at different shooting positions.

One day I visited there new studio which was in a building that had been a former super market. They had Knox light boxes, the great big floor standing ones with two boxes, a horizontal and a vertical one at each photographer’s position so that chromes could be evaluated.
The boxes had masking tape with numbers written all over the illuminated surfaces. Numbers on each box varied widely.
Being curious, I asked why? The answer was that each tape spot showed the variation in K and output across the surfaces from the manufacturer’s spec.

They quickly replaced all of the boxes.

The funny thing was that I was there on a very hot, sunny day. The supermarket had lots of windows that the studio painted black to keep sunlight out and blocked curious bystanders. While we were talking there was a very loud explosion and glass all over the place. The black paint caused some of the windows to explode!

BTW, the first order for matched lenses was for Apo Ronars, but they were shooting three dimensional objects on a flat table and put multiple items on the table to be shot at the same time to be separated by the art department later. But things at the edge just weren’t as critically sharp as at the center. So they then ordered matched Makro Sironars and eliminated that problem.

[biedron]

Depends on the print...

Some are best viewed in total darkness :)

[Drew Wiley]

How I achieve true DMax is to leave the test strip drying about 30 sec too long in the toaster oven. True deep neutral black every time, once you clear the smoke out of the room.