I performed a safelight test today and found my 902 ILFORD filters seem to be fading away somewhat. I have the 'DL20' unit in the centre of my darkroom with a 12"x10" filter on the top and a 10"x8" filter on on the bottom (25W lamp). I'm in the early stages of thinking about constructing an LED amber safelight, the electronics don't seem too complicated, I'd run the unit off a DC power suply, however I'm not 100% sure on housing construction for the LEDs. Has anyone built something along these lines? I'd prefer amber as the peak transmission seems to be compatible with the ILFORD MG papers and I prefer the light compared to red.
Building LED safelights?
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I’ve done some research as I have thought about making my own, but haven’t really got around to it as I mostly make alt process prints.
The wiring isn’t all that bad like you said, however finding led strips with the right spectrum is the hard part. LEDs have a range greater than their specified peak spectrum. I believe amber LEDs might come a little too close to be truly safe.
These are very expensive but do show a graph of the emission spectrum. The amber LEDs do seem to emit some light near the 540nm range which is within the sensitivity of ilford papers. https://store.waveformlighting.com/...s/products/simplecolor-amber-led-strip-lights
The wiring isn’t all that bad like you said, however finding led strips with the right spectrum is the hard part. LEDs have a range greater than their specified peak spectrum. I believe amber LEDs might come a little too close to be truly safe.
These are very expensive but do show a graph of the emission spectrum. The amber LEDs do seem to emit some light near the 540nm range which is within the sensitivity of ilford papers. https://store.waveformlighting.com/...s/products/simplecolor-amber-led-strip-lights
MattKing
Moderator
You could put LEDs with a useful spectrum behind the Ilford filters.
I am currently using the red LEDs of my headlamp as a safelight. The 7 minute Kodak safelight test is successful with Ilford MGRC paper, even when the safelight is mostly shining on the paper from a distance not more than 1.5 m. However, Fomaspeed Variant III gets fogged in no time.
I have found it difficult to find precise information on both paper sensitivity and LED emission spectrum. If you don't mind a little experimentation, I would suggest starting off with a batch of cheaper LEDs, or maybe a couple batches and test them for safety with an improvised setup. I will do this for some amber LEDs as I also like this color much better than red.
I have also bought some darker red Roscoe gel filters that I plan to put in front of my headlamp to try and make it safe for Foma in the short term, as Matt suggested.
I have found it difficult to find precise information on both paper sensitivity and LED emission spectrum. If you don't mind a little experimentation, I would suggest starting off with a batch of cheaper LEDs, or maybe a couple batches and test them for safety with an improvised setup. I will do this for some amber LEDs as I also like this color much better than red.
I have also bought some darker red Roscoe gel filters that I plan to put in front of my headlamp to try and make it safe for Foma in the short term, as Matt suggested.
There are different red leds too, it seems. Some are called "deep red" or "far red":
https://www.ebay.com/itm/1-5-10-50m...754637&hash=item3ae090e256:g:hjgAAOSwSypY9YMx
https://www.ebay.com/itm/1-100PCS-3...775198&hash=item4aec154922:g:ly4AAOSwz8xdR63n
and some amber strips:
https://www.ebay.com/itm/Waterproof...ispr=1&hash=item33d699e13f:g:9c0AAOSwKUhZuTPI
https://www.ebay.com/itm/1-5-10-50m...754637&hash=item3ae090e256:g:hjgAAOSwSypY9YMx
https://www.ebay.com/itm/1-100PCS-3...775198&hash=item4aec154922:g:ly4AAOSwz8xdR63n
and some amber strips:
https://www.ebay.com/itm/Waterproof...ispr=1&hash=item33d699e13f:g:9c0AAOSwKUhZuTPI
I have a Paterson red safelight installed for the Foma papers due to this.
On Fotoimpex page it says the Paterson light might fog Variant papers? (if translated correctly)
https://www.fotoimpex.com/fotolabor/paterson-dunkelkammerlampe.html
"Helles orangenes DUKA Licht für Ilford Multigrade und Agfa/ADOX MCP/MCC. Fomaspeed Variant kann bei diesem Licht verscheleiern. Die Birne in der Lampe kann gewechselt werden. Hat im Gegensatz zur AP Lampe keinen Schalter. Die Lampe wird also durch ein und ausstecken "geschaltet".
"Bright orange DUKA light for Ilford Multigrade and Agfa / ADOX MCP / MCC. Fomaspeed Variant can blur in this light. The bulb in the lamp can be changed. In contrast to the AP lamp, it has no switch. The lamp is "switched" by plugging it in and out. "
.. maybe this would work with Foma? https://www.fotoimpex.com/fotolabor...-led-4018-mit-rotfilter.html?cache=1611912825
Interesting. My Paterson lights have red filters. I wonder what they suggest? On second thoughts, they seem to be referring to a Kaiser DUKA safelight.
no need to do anything like that, you can buy RGB LED video lights and just turn them to full red. They also let you control the brightness and come with standard mounting options. Then when you need standard lighting, just turn them to white light.
Are you saying that RGB video lights at red don't fog papers such as Variant?
that would be subject to testing, though I know of at least one person that uses these in their darkroom: https://www.bhphotovideo.com/c/product/1492247-REG/gvm_800d_rgb_led_video_studio.html/overview
for $100 it has dedicated rgb LEDs and you put the hue at 360 degrees and 100% saturation to get red. I’m pretty certain none of the LEDs except the red ones are emitting light, though whether it’s far enough up the spectrum to not fog all papers should be tested.
and don't forget film handling. all'pan'chromatic film will be problematic with amber safelights!
SuperBrightLEDs.com sells red and amber LED bulbs for standard (medium screw base) lamp sockets. The amber has been tested by a Photrio member and found completely safe for most multigrade papers, and they also sell a red with a pretty narrow emission band. Inexpensive, and far brighter than you need -- a single 2W lamp gives 27 Lumen, and most conventional safelights are less than half that output.
In 2017 I soldered a safelight from 25 LEDs, which has been working very well for me. It is a naked prototyping board without case. I have it standing on the hot water tank in the boiler room, which houses my dark room.
The LED are standard 5mm through hole with clear, colourless housing. The semispherical top of the LED does some focussing at I'm getting a large, red spot on the white concrete ceiling which illuminates the room. On top of the tank there is no direct line of sight from the individual LED to the surface of my table, including the base board of the enlarger. Once I lift the paper from the base board to my Nova processor such line of sight will be establised and the paper will also get closer to the red ceiling spot.
So far I haven't noticed any bad effect, including on Foma papers. I did a test once using a step wedge to check if the papers contrast is affected. I can't remember which of my papers I checked, neither the time of exposure to the red light. At full blast I thought that I saw a tiny effect in the deep blacks (i.e. the most transparent steps of the Stouffer wedge) and thus disabled two of the five rows on my 'safe light'. The control was a piece of paper that I handled identically, but in total darkness. I should do a proper test at some point. Especially now that I have a densitometer.
I use Adox MCC/MCP and Fomabrom as well as Fomatone. I was gifted some old Ilford MGIV paper, mostly RC, from 1992 or older. I haven't had any problems with that either.
The array of LEDs is organised into five rows. In each row there are five LED in a serial configuration. If one were to die the entire row would fail. For each row I added a jumper, which can enable/disable the row. As I said, I have only three of the five rows running. It is still plenty bright enough. All 25 LED enabled is obscenely bright.
I'm using a cheap 12V power supply (wall wart type) and soldered an inline switch into the cable. There is one resistor for each row, which I calculated to yield about 20mA of current, which is the nominal value for those LEDs. I can't remember the value but it is easy to calculate: Each LED has a forward voltage drop of nominally 1.8V. 12V-(5x1.8V)=3V. So 3V will have to drop at the resistor and using Mr. Ohms Law I'm getting, wait..., 150 Ohm. The LED have a max rating of 30mA, so 120 Ohm giving 25mA are still good and I may even have used that. Whatever I had around then.
The LED are Kingbright L-53SR superbright LED with peak intensity at 660nm according to the data sheet. Most red LED have a lower wavelength. 660nm is sometimes called deep red.
I have an X-Rite Colormunki Photo to profile my computer screens for more accurate colours. This device is not a colorimeter like most others but a spectrophotometer. It can record a full spectrum. Recently I bought an App for my Android phone and tablet, which uses the Colormunki to give me a Colourmeter.
I used that to check the spectrum of one of those LED. I have two on a non solder breadboard as a make shift savelight for use at home in my bathroom, which is my negative darkroom. Very rarely I develop some direct positive paper at home and I use this then for convenience. I did lower the current for this experiment to prevent saturation of the sensor.
The spectrum I collected shows peak intensity just below the advertised 660nm. It's about 657nm according to this sensor.
There is a little bug in the apps plotter and most of the time the units on the y-Axis are scrambled. I'll have to report that to the author. But using the grid I can see that the peak is about 10.5 major grid units high. So lets say 10 for easy reading from the plot. When I go left and down to 10% intensity it is at 630nm. At 620nm we're at 4% intensity. At 600nm it is barely registering, and at 585nm and below the device can't detect any intensity.
Foma says that the safe light for my two papers should emit above 610 and 625nm. I believe the order was Fomabrom and Fomatone. I didn't look up Fomaspeed. I assume it'll be like Fomabrom FB paper. Ilford and Adox can take safe lights with shorter wavelength, as you know.
In conclusion: This safe light cost me very little money and not much time to solder. Which I did at work with our nice Weller rework station. Thanks boss! After having previously used a simple 230V red darkroom bulb from Dr. Fischer in desklamp this was a major upgrade. I have enough light in the entire room to navigate and a high level at the table. The spectrum of the emitted light looks pretty perfect and in practice I haven't had any noticable problems. What I may want to do at some point is to test in a more scientific manner if there are any measurable effects on paper contrast.
The LED are standard 5mm through hole with clear, colourless housing. The semispherical top of the LED does some focussing at I'm getting a large, red spot on the white concrete ceiling which illuminates the room. On top of the tank there is no direct line of sight from the individual LED to the surface of my table, including the base board of the enlarger. Once I lift the paper from the base board to my Nova processor such line of sight will be establised and the paper will also get closer to the red ceiling spot.
So far I haven't noticed any bad effect, including on Foma papers. I did a test once using a step wedge to check if the papers contrast is affected. I can't remember which of my papers I checked, neither the time of exposure to the red light. At full blast I thought that I saw a tiny effect in the deep blacks (i.e. the most transparent steps of the Stouffer wedge) and thus disabled two of the five rows on my 'safe light'. The control was a piece of paper that I handled identically, but in total darkness. I should do a proper test at some point. Especially now that I have a densitometer.
I use Adox MCC/MCP and Fomabrom as well as Fomatone. I was gifted some old Ilford MGIV paper, mostly RC, from 1992 or older. I haven't had any problems with that either.
The array of LEDs is organised into five rows. In each row there are five LED in a serial configuration. If one were to die the entire row would fail. For each row I added a jumper, which can enable/disable the row. As I said, I have only three of the five rows running. It is still plenty bright enough. All 25 LED enabled is obscenely bright.
I'm using a cheap 12V power supply (wall wart type) and soldered an inline switch into the cable. There is one resistor for each row, which I calculated to yield about 20mA of current, which is the nominal value for those LEDs. I can't remember the value but it is easy to calculate: Each LED has a forward voltage drop of nominally 1.8V. 12V-(5x1.8V)=3V. So 3V will have to drop at the resistor and using Mr. Ohms Law I'm getting, wait..., 150 Ohm. The LED have a max rating of 30mA, so 120 Ohm giving 25mA are still good and I may even have used that. Whatever I had around then.
The LED are Kingbright L-53SR superbright LED with peak intensity at 660nm according to the data sheet. Most red LED have a lower wavelength. 660nm is sometimes called deep red.
I have an X-Rite Colormunki Photo to profile my computer screens for more accurate colours. This device is not a colorimeter like most others but a spectrophotometer. It can record a full spectrum. Recently I bought an App for my Android phone and tablet, which uses the Colormunki to give me a Colourmeter.
I used that to check the spectrum of one of those LED. I have two on a non solder breadboard as a make shift savelight for use at home in my bathroom, which is my negative darkroom. Very rarely I develop some direct positive paper at home and I use this then for convenience. I did lower the current for this experiment to prevent saturation of the sensor.
The spectrum I collected shows peak intensity just below the advertised 660nm. It's about 657nm according to this sensor.
There is a little bug in the apps plotter and most of the time the units on the y-Axis are scrambled. I'll have to report that to the author. But using the grid I can see that the peak is about 10.5 major grid units high. So lets say 10 for easy reading from the plot. When I go left and down to 10% intensity it is at 630nm. At 620nm we're at 4% intensity. At 600nm it is barely registering, and at 585nm and below the device can't detect any intensity.
Foma says that the safe light for my two papers should emit above 610 and 625nm. I believe the order was Fomabrom and Fomatone. I didn't look up Fomaspeed. I assume it'll be like Fomabrom FB paper. Ilford and Adox can take safe lights with shorter wavelength, as you know.
In conclusion: This safe light cost me very little money and not much time to solder. Which I did at work with our nice Weller rework station. Thanks boss! After having previously used a simple 230V red darkroom bulb from Dr. Fischer in desklamp this was a major upgrade. I have enough light in the entire room to navigate and a high level at the table. The spectrum of the emitted light looks pretty perfect and in practice I haven't had any noticable problems. What I may want to do at some point is to test in a more scientific manner if there are any measurable effects on paper contrast.
I think the OP states the filters are starting to fade, so that is not an option.
MattKing
Moderator
They may still attenuate unwanted spectral spikes.
I've put in a 15W lamp (incandescent) that is likely safer than the 25W, as my darkroom ceiling is fairly low.
Thanks for the pictures and the comprehensive description of your LED set-up.
I now have some components on order so will report back in due course.
So I've assembled the components but haven't had a chance to test with paper yet. Brightness with 16 LEDs is impressive.
MattKing
Moderator
And your illustrative photo ain't half bad!
Thanks. Power consumption measured at the mains PSU is around 1.8 - 2W.
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