safelight vs. plain old red bulb

[curiousart]

Hi Folks,

I'm very nearly ready to do some printing in my very first darkroom...

I'm wondering if someone could tell me what advantage a large safelight has over a plain red bulb in a light socket? So far, in all my reading, I can't seem to discover why people use them over the old fashioned ruby light. Sorry if this has been discussed to death, I couldn't seem to find an answer in older posts.

Best,
Art

[Sirius Glass]

A red bulb may not block the right bands of color and therefore black & white paper may get fogged. Go with a safelight or safelight bulb.

Steve

[RalphLambrecht]

Art

Steve is right. Also, I've seen the paint slowly come off, creating 'unsafe' lighting. The purpose of a safelight is to protect your paper for as long as possible. No safelight does that 100%, but typically, a good safelight protects for 20-30 minutes against fogging. To be sure if a simple and inexpensive light works, one needs to test.

I can offer a free chapter from our book which explains the test in detail:

http://www.waybeyondmonochrome.com/W...ghtTestEd2.pdf

If you want to keep it simple, start with the coin test on the last page.

[curiousart]

Good points. I guess after all the bread I've put out on other gear and materials, it doesn't make sense to cheap out on the safelight! B+H has the Arkay 5x7 for under 30 bucks.

[Ian C]

Originally, all photographic papers and films were orthochromatic. That meant that they were partially blind to red light. Consequently, these materials could be used in a darkroom with dim red safelights provided that the exposure was limited in both time and intensity.

Later, films and papers were made sensitive to all, or nearly all, colors of light. These modern materials sensitive to all colors are called panchromatic. Panchromatic papers are somewhat insensitive to the amber-colored light passed by a Kodak OC safelight filter.

The Kodak OC filter is the correct filter to use with panchromatic black-and-white papers. Black-and-white panchromatic films are too sensitive to use under any safelight in most cases.

Just about all printing papers are now panchromatic and should be used under a relatively weak OC-filtered safelight. There are still a few orthochromatic papers from Europe, such as Foma that require a dim red safelight filter.

In general, panchromatic papers are not safe under red filters and simple red bulbs generally don’t have the accurate filtering properties of a safelight and a Kodak OC filter.

[curiousart]

Ian, thanks for the lucid description. That's exactly what I was looking for in the few books I've read so far that simply say "get a safelight" (What's a safelight? What kind? Why won't a red bulb work?)

Ralph, I've been reading the excerpts from your book for awhile, the book looks like a must-have. I'll check it out.

Best,
Art

[RalphLambrecht]

Originally, all photographic papers and films were orthochromatic. That meant that they were partially blind to red light. Consequently, these materials could be used in a darkroom with dim red safelights ...

True!

... Later, films and papers were made sensitive to all, or nearly all, colors of light. These modern materials sensitive to all colors are called panchromatic. Panchromatic papers are somewhat insensitive to the amber-colored light passed by a Kodak OC safelight filter.

The Kodak OC filter is the correct filter to use with panchromatic black-and-white papers. Black-and-white panchromatic films are too sensitive to use under any safelight in most cases.

Just about all printing papers are now panchromatic and should be used under a relatively weak OC-filtered safelight. There are still a few orthochromatic papers from Europe, such as Foma that require a dim red safelight filter.

In general, panchromatic papers are not safe under red filters and simple red bulbs generally don’t have the accurate filtering properties of a safelight and a Kodak OC filter.

Ian

There are no panchromatic papers (only film) unless you're are talking about direct-positive papers.

OC filters have nothing to do with orthochromatic vs panchromatic. They are just a compromise between safelight protection and maximizing human visual sensitivity. OC filters are great for many modern papers with very limited red sensitivity (true orthochromatic papers). They are not so good with red-sensitive papers (Foma). A red safelight is always 'safer' than OC filtration, but not as bright to us humans as OC filtered light.

[2F/2F]

Good points. I guess after all the bread I've put out on other gear and materials, it doesn't make sense to cheap out on the safelight! B+H has the Arkay 5x7 for under 30 bucks.

Bulbs are about five bucks. You don't necessarily need a can. I put my safelight bulb in a regular wall lamp socket. You could use a thrift store lamp somewhere in your darkroom if you don't have a wall fixture in there. A dual fixture overhead with separate wall switches for the red light and the regular light is ideal IMO.

And it should be a "proper" safelight bulb, not one of those Halloween red lights, so that the proper frequencies are blocked.

[MattKing]

I'm afraid I have to differ a bit with Ian.

As far as I am aware, no regular black and white paper is panchromatic. Only the now discontinued Panalure was panchromatic, and that was designed for making black and white prints from colour negatives. Panchromatic means sensitive to all visible light.

Older orthochromatic materials were sensitive to blue light mainly, with some lower sensitivity to green. You would use a red safelight with them, but that isn't ideal, because our eyes aren't particularly sensitive to red. Our eyes tend to be more sensitive to the light from a Kodak amber (OC) safelight, so we would like to be able to use those safelights (the darkroom seems much brighter), but as most orthochromatic materials were not designed for use with an OC safelight, one needs to test whether they are compatible.

The newer (and now more common) materials that are designed for an OC safelight have a narrow band of insensitivity that matches the light output from that safelight. Most of them are also insensitive to the red light emitted by safelights designed for orthochromatic materials, but again it is very important to test.

Other manufacturers make safelights to the OC standard.

Regular "red" bulbs aren't necessarily sources of sufficiently narrow spectrum red light, so they cannot be relied upon without testing.

It is possible to use some of the single spectrum LED lights that are new to the market for safelight use, but because they aren't tested or marketed for that purpose, you end up doing the testing yourself. I'm currently using two of those red LEDs, but I have older safelights to fall back on.

[Worker 11811]

I have been using a double layer of Rosco R-27 gel as a safelight filter and it has done well for me.

My darkroom has a recessed fixture in the ceiling. It has a regular 50 watt incandescent bulb. I took the frosted glass out of the frame sandwiched two layers of R-27 gel in there before putting the glass back in.

One layer of R-27 has a 4% transmission rating and, according to the company's charts blocks nearly all wavelengths shorter than 500-550 nm. The curve doesn't start toeing up until 600 nm. Putting a double layer of gel in the frame just gives a little more filtration.

The light in my room is a good 6 feet or more from any work area and you would have to stand directly under the fixture for any light to shine directly on anything.

While I am confident that my safelight is good for at least 15 minutes under normal working conditions I am still careful to bring paper out of its container for only the minimum amount of time needed to perform the task at hand. I have a spare empty box left over from a previous batch of photographic paper that I use as a makeshift paper safe. If I have paper out any longer than is necessary to print and develop, it goes in the box/paper safe.

I also keep my paper safe in a drawer and my fresh paper stock in another drawer. Those drawers are closed at all times except when I am actually taking something out or putting them in and I never open those drawers unless the room is under safelight or complete darkness.

Aside from providing protection from safelights that may or may not be completely safe, it also helps minimize damage in case the door gets opened or the white lights get turned on by accident.