Kodak OC safelight filters

[Doremus Scudder]

I think about replacing the incandescent 15W or 25W in my regular safelights by LED equivalent 2 to 5W to reduce the heat and for the energy efficiency. Is the 0C filters will still be safe or if the safelight filter design was studied specifically with incandescent bulbs and fogging tests needed?

Ginette,

Yes, if you filter the LED with your normal OC filter, you will ensure that the light coming through is "safe" as far as wavelengths go. A safelight test is still a good idea, as the intensity may be much higher. If there is a problem there, then a lower wattage bulb or greater distance from the sensitive material may be needed. However, the 2-5w bulb should be about the same brightness as the incandescents you are already using.

Best,

Doremus

[HMG]

I would agree with Doremus. It can be a bit difficult to translate bulb wattage to lumens, but I suspect a 5w LED may produce more lumens than a 15w (and maybe even a 25w) incandescent.

[LabRat]

As for brightness, my rule for myself is to never have a safelight directly illuminating material, as it should be bouncing off some light colored surface (like a painted ceiling), but not directly aimed at materials (let the inverse square law increase the distance/reduce intensity to the materials)...

But I prefer a dimmer workroom, and develop B/W prints by time and test strip, rather than inspection... (And my fingertips become "eyeballs"...) I figure that a lab rat should be able to operate everything with their eyes closed (and blindfolded too)... I've done enough color, too to get the "feel" of everything...

I have been in some printing rooms that my first impression is that they are lit like a stadium (and makes me uneasy about fogging an opened fresh box of paper)... I look for the darkest, shaded corner before I crack open the box!!! And I don't leave unused materials laying around, and box or process exposed stuff ASAP, before lightning hits the building 3 times in a row...

;-)

Steve K

[denverjims]

I think about replacing the incandescent 15W or 25W in my regular safelights by LED equivalent 2 to 5W to reduce the heat and for the energy efficiency. Is the 0C filters will still be safe or if the safelight filter design was studied specifically with incandescent bulbs and fogging tests needed?

There are a couple of factors. The filter works by mostly letting light through in the wavelengths which the paper is not sensitive to. However, that "mostly" is the problem. Most filters are not 100% opaque in frequencies where the paper is sensitive so allow some light through. If the light source is putting out enough energy in those frequencies the small amount the filter allows through will still do harm. Not knowing what the spectral output your LED will provide or the brightness, it is not possible to know about the safety. If it is either bright enough overall or puts out a spike in an area that the filter does not cut out, you could have problems.

As a generalization, it will probably be fine. Personally, I'd to the testing. The time & materials used in testing are not that great given the risk. Your call...

[Ginette]

I wish to try some LED into my regular safelights, my idea is to reduce energy cost but also reduce the degradation of the filters that are probably relied more to the heat that to the light itself.
I ordered these 2 LED from Superbrightleds, I choose warm white for both:
- for the 10x12" safelights UPC: 847781014662 6W, equivalent 30W https://www.superbrightleds.com/more...gree/436/1466/
- for the small Kodak 5 1/2" the UPC: 847781014808 equivalent 10W like their little well know red bulb https://www.superbrightleds.com/more...bulb/440/1480/
I will do tests on them.

[denverjims]

Hi Ginette,
This may be a little late but your testing of these bulbs with whatever safelight you plan to use would be wise. If you use Ilford FB Classic, for instance, you will see in the technical specification:
https://www.ilfordphoto.com/amfile/f...roduct_id/733/
that the paper is sensitive from around 360nm to around 570nm. If you click on specifications for the UPC: 847781014808 you will see that even the red "only" bulb puts out some energy below 570. There may be an issue if the exposure is close/long enough. (No spectral curve was showing for the UPC: 847781014662).

The other thing is that both of these unbranded bulbs are likely from places where the specs may not be solid.

Like Ronald Reagan said: "Trust but verify".
Best, Jim

[Duolab123]

Buy a used Thomas super safe light. The filters can be pretty ratty and still work. Low pressure sodium vapor lamps are super narrow spectral output. The bulbs are nothing special, you can find OEM bulbs on ebay for 25 bucks and they last forever. I have 3 , I have the DUC color filters in the outer filter holders. You can see and make color prints, I didn't believe it until i tried it. Of course it takes 5 minutes for your eyes to adjust to the darkness. With the vanes open for black and white You could easily read a large print book.