Building LED safelights?

[M Carter]

All well and good, but red safelight will produce a cyan fog on RA-4 materials. I'm perfectly okay with dim for color, but I'd really rather not work in total darkness if I can get even "not bang my head on the enlarger head" levels of safelight for that task. And the amber is much more comfortable for B&W printing as well. I do have an old red bulb safelight, so I can still use that for ortho materials like Harman Direct Positive.

I didn't know you could have any sort of light with RA-4, only doing B&W here (well, if they still made ciba I'd be into color I suppose!)

I use enough red-only materials that I'm happy with red, I don't have issues with the color personally, just really pleased with how bright the room is. My darkroom's pretty big and I also have a spray booth for big emulsion projects, red bulbs everywhere.

 

[Donald Qualls]

I didn't know you could have any sort of light with RA-4

It's a source of some controversy, but there's a very deep valley in the spectral sensivity curves of the three layers of RA-4 paper, where the red and green curves cross around 585 or so nanometers. The way I read the chart for Fuji Crystal Archive, that specific wavelength is five to seven stops less sensitive than the peak of the green curve. That means you can put a dim light right in that valley and it will take long enough to produce noticeable fogging to let you work in "man, it's dim in here" rather than total darkness. And that's a HUGE difference.

 

[M Carter]

It's a source of some controversy, but there's a very deep valley in the spectral sensivity curves of the three layers of RA-4 paper, where the red and green curves cross around 585 or so nanometers. The way I read the chart for Fuji Crystal Archive, that specific wavelength is five to seven stops less sensitive than the peak of the green curve. That means you can put a dim light right in that valley and it will take long enough to produce noticeable fogging to let you work in "man, it's dim in here" rather than total darkness. And that's a HUGE difference.

Hard enough to drop a dodging tool on the floor with old-school red (and dim) safelights and try to find the damn thing!

 

[Tom Kershaw]

Here is my latest update showing the ILFORD housing with the top '902' off for demonstration purposes.

 

[bernard_L]

that seller (SuperBrightLEDs) also has an amber bulb that has its peak at 590nm -- it's been confirmed by other users here to be safe on most VC and graded papers

Beware, though, with the (otherwise excellent) Foma papers --the multigrade ones--.

 

[Donald Qualls]

Beware, though, with the (otherwise excellent) Foma papers --the multigrade ones--.

Yes, I've read about that -- they're sensitive further into yellow than most multigrade. That's fine, I'm used to red for printing; I bought to amber mainly in hopes I could use it for RA-4.

 

[urnem57]

FWIW - I used 2 Superbright red LED bulbs with both Foma Emulsion and J Lane plates with no issues. They work for me.

 

[Danner]

I've had these bulbs, and some larger red LED's from amazon.com up and running for a while now. My darkroom is nice and bright, and sections of Ilford MGIV paper laying around for 5 minutes have no fog at all. Very happy with these. Recommended.

 

[wiltw]

It amazes me about the persistence of use of RED in the darkroom when even Kodak buiilt safelights that were furnishd with AMBER filters since the 1960's.
I used Jobo safefights, purchased in the early 1990s, which used LEDs in 3-position lens safelights which were designed for use with B&W paper, color neg print paper, and color transparency print paper. As I no longer had space to set up a darkroom, I recent sold off a considerable portion of equipment, including two Jobo MaxiLux 6240 LED safelights.

 

[MattKing]

It amazes me about the persistence of use of RED in the darkroom when even Kodak buiilt safelights that were furnishd with AMBER filters since the 1960's.

It has more to do with the relatively good availability of red LEDs that work with photographic paper vs. amber LEDs that work with photographic paper.
A lot of us can't just place an order to a US supplier and get something shipped quickly and cheaply.
My red LED (Christmas) rope lights - all 16 feet of them - make my darkroom brighter and easier to work in than the really good Thomas units I used to enjoy in commercial darkrooms, and unlike the Thomas I can turn them off and on whenever I need to.

 

[Danner]

It amazes me about the persistence of use of RED in the darkroom when even Kodak buiilt safelights that were furnishd with AMBER filters since the 1960's.
I used Jobo safefights, purchased in the early 1990s, which used LEDs in 3-position lens safelights which were designed for use with B&W paper, color neg print paper, and color transparency print paper. As I no longer had space to set up a darkroom, I recent sold off a considerable portion of equipment, including two Jobo MaxiLux 6240 LED safelights.

That was in the days of mostly graded papers. Variable contrast paper has a broader spectral sensitivity (Ilford is 350-550 nanometers). Orange light is in the 590-625 NM range, and red light is in the 625-700 nm range. Red LEDs are about 630 nm, monochromatic. Sodium lights, also monochromatic, are 589 nm. The roll-off of the paper sensitivity above 550 nm is somewhat gradual, so the higher above 550 nm, the less change of fogging over extended periods of time. Red is safer than orange. Also, red LEDs are widely available. I don't see any advantage to using orange lights. Just turn-up the brightness of the red I also see no need to use some sort of ancient contraption to hold lamps with filters in front of them when monochromatic LEDs are readily available. IMHO.

 

[wiltw]

That was in the days of mostly graded papers. Variable contrast paper has a broader spectral sensitivity (Ilford is 350-550 nanometers).
.

Gee, printing in the 1960s and 1970's I used Polycontrast paper and filters, and almost never used graded paper, under OC filtered safelight!

I just consulted the Kodak Master Darkroom Dataguide, from mid-1960's, and Kodak describes the OC filter (light amber)

"Provides maximum safety for (list)...Polycontrast".​

 

[Tom Kershaw]

A lot of us can't just place an order to a US supplier and get something shipped quickly and cheaply.

I suspect some of our US contributors don't appreciate how much choice, availability, and convenience they have compared to the UK or Canada.

 

[pentaxuser]

I suspect some of our US contributors don't appreciate how much choice, availability, and convenience they have compared to the UK or Canada.

That was my perception as well, Tom. It is always a problem whenever a U.K. or maybe a European is looking for information on LEDs and stuff that we cannot get here or we cannot be sure that U.S. LED X is the same as U.K. LED Y

Not the U.S. members' faults of course it's just that it prevents info on specific stuff available in the U.S. being as useful as it might be

Tom for clarification: Are these the same 16 leds you had in the transparent box hung by strings from the ceiling and with the Ilford filter over them how does the light compare to the former 25W incandescent?

I have the 902 and recently changed my 15W incandescent bulb for the 25W. While the light is quite a bit better I am now worried that my filter may not now be good enough so your light comparison info will be useful

Thanks

pentaxuser

 

[Nicholas Lindan]

A lot of us can't just place an order to a US supplier and get something shipped quickly and cheaply.

Three large electronics distributors have Canadian divisions - Newark/Element14, Digikey, and Mouser - and I'm sure there are more.

 

[Tom Kershaw]

Tom for clarification: Are these the same 16 leds you had in the transparent box hung by strings from the ceiling and with the Ilford filter over them how does the light compare to the former 25W incandescent?

I currently have the red LEDs installed, whereas the original approach you mention utilised amber LEDs. With the red option the light is much lower. I haven't yet tried the amber LEDs within the 902 enclosure, this will be a next step. There does seem to be a "spectrum of safety" as regards safelighting, with Ilfobrom Galerie at one end and possibly the Foma papers and other fast options at the other.

 

[koraks]

amazes me about the persistence of use of RED in the darkroom when even Kodak buiilt safelights that were furnishd with AMBER filters since the 1960's.

Red works with all contemporary b&w papers, amber works with most, but not all. Try printing on fomabrom with an amber safelight...
Btw, I also have one of those Jobo three-colored safelights. It's about as effective as trying to light a soccer game in a stadium with a flashlight.

 

[radiant]

Sparkfun has an interesting product:

Triad Spectroscopy Sensor

" The Triad is made up of three sensors; the AS72651, the AS72652, and the AS72653 and can detect the light from 410nm (UV) to 940nm (IR). In addition, 18 individual light frequencies can be measured with precision down to 28.6 nW/cm2 and accuracy of +/-12%."

https://www.sparkfun.com/products/15050

With this one could measure the safelights pretty easily?

 

[wiltw]

Red works with all contemporary b&w papers, amber works with most, but not all. Try printing on fomabrom with an amber safelight...
Btw, I also have one of those Jobo three-colored safelights. It's about as effective as trying to light a soccer game in a stadium with a flashlight.

Ha ha! I only used mine for color work, so dimness was inherent to color printing, and I never noticed the brightness of B&W.

As for Fomabrom, this from their tech data sheet

"FOMABROM is routinely processed at indirect safety illumination with wavelength of 575 nm and higher, corresponding colour of safety illumination is yellow, yellow-green, amber or orange colours are recommended."​

...no mention of Red!
I know red is for Orthochromatic materials, but I don't know offhand anything modern that fits that description apart from lithographic films.

 

[Donald Qualls]

I know red is for Orthochromatic materials, but I don't know offhand anything modern that fits that description apart from lithographic films.

Ilford Ortho 80, comes in 35mm, 120, and 4x5. Not to mention "green sensitive" x-ray films, sizes up to HUGE...

 

[wiltw]

Thx for the info, Donald! Coming from a medical imaging background, I was aware of X-ray film, but like lithgraphy, I do not consider that to be usually in the realm of amateur photography. So the fact that Ilford has a consumer ortho film was eye opening.

 

[lantau]

Ha ha! I only used mine for color work, so dimness was inherent to color printing, and I never noticed the brightness of B&W.

As for Fomabrom, this from their tech data sheet

"FOMABROM is routinely processed at indirect safety illumination with wavelength of 575 nm and higher, corresponding colour of safety illumination is yellow, yellow-green, amber or orange colours are recommended."​

...no mention of Red!
I know red is for Orthochromatic materials, but I don't know offhand anything modern that fits that description apart from lithographic films.

You quoted the specs of the fixed contrast Fomabrom. Fomabrom Variant requires 625nm or higher.

 

[wiltw]

You quoted the specs of the fixed contrast Fomabrom. Fomabrom Variant requires 625nm or higher.

I was not previously aware of this Orthochromatic VC paper. Thx.