I will report back again once I have an impression of how "safe" the light is. My visual perception is that the LEDs are producing a fairly monochromatic output, in accordance with the specified 590nm, although I don't have a tool to measure this.
Brilliant! If my breadboard will ever have to vacate the top of the water tank I might just steal that housing solution from you!!
Did you check with a cd/dvd? It gives a good impression of any spectral impurities, although it only does so qualitatively - i.e. it does show if the leds emit other colors than the ones they are specified for, but it's hard (impossible) to tell how much of that undesirable light is present exactly. It's a good starting point for trouble shooting though.My visual perception is that the LEDs are producing a fairly monochromatic output, in accordance with the specified 590nm, although I don't have a tool to measure this.
Did you check with a cd/dvd? It gives a good impression of any spectral impurities, although it only does so qualitatively - i.e. it does show if the leds emit other colors than the ones they are specified for, but it's hard (impossible) to tell how much of that undesirable light is present exactly. It's a good starting point for trouble shooting though.
Yes. Sort of. But not quite. And that's why it's necessary to test.red LEDs are monochromatic.
Yes. Sort of. But not quite. And that's why it's necessary to test.[/qoute]
Fully agree. @Danner I have fogging on Foma RC paper with red LEDs, not with LEDs covered with filters.
For example some people have noticed that even with relatively narrow band red LEDs peaking anywhere between 620nm and 660nm,
graded papers are basically blue-sensitive emulsions typically with comparatively little sensitivity into the green spectrum
Since they are apparently targeted for use on signs, one might also wonder how reliable the spectral distribution is for batches made over longer time periods.
Same here. Two layers of rubylith, in fact, in my case. But granted, it works very well this way.My attempts to use a red LED bulb with Fuji green sensitive X-ray film wound up with a Rubylith filter to avoid fog,
The extended lifetime of the filter will be mostly because it probably won't get as warm as with an incandescent bulb. A filter doing 'work' isn't really degrading it significantly, except if it has to deal with a lot of UV light, which tends to break down filter dyes. This of course is by definition not much of an issue with incandescent sources (heat, however, very much is!)It's still better than using an incandescent light source in the sense that the filter is doing less "work", which means it should last significantly longer.
Visible light is rather low energy and doesn't easily break the carbon bonds in dyes. It won't contribute much at all to filter degradation as a result. The story is different for UV.Hi Koraks, what I mean by filter "work" is simply that it needs to absorb less radiation - all typical filters using dyes (as opposed to dichroic/interference) work by absorption, which is largely what causes them to degrade.
Thanks for that, I just ordered 5 of them. [beerclink]Many people in the US are using these cheap red LED bulbs - they fit in any standard lamp socket, and their spectrum doesn't overlap (the spectrums are on the web page). I have 3 to 5 going at any one time, they're fantastic.
I haven't tested them yet, but 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 (though I wouldn't trust it on ortho films). I have hopes for it, at suitable levels of attentuation, to be a viable RA-4 safelight as well, given it's within a few nanometers of the same wavelength as the low pressure sodium lamps of Thomas and Duka safelights.
Unfortunately this product doesn't seem to be available on the UK / European market. I've not had a chance yet to re-build my safelight with the extra LEDs but should do soon.+1 for The Red Superbright LED bulbs. I
Just go with the red and you're good for papers and for ortho film (I don't know of any papers that can't do red, I suppose there could be some?)
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