Thomas Duplex Safelight Questions

[Kevin Crisp]

As I mentioned, I got a Craigslist pair of these for $12.50 each. I am a big spender. They both needs bulbs and filters and some cleaning up. Or maybe new cords and not bulbs, I haven't started on them yet.

My question is, if I only use them for b&w printing, with the vanes always open some to let the orange-ish light out, does it really matter at all what is in the upper/outer slots of the moving vanes? I didn't realize (I have had one of these for years) that the vanes apparently do have some deep, dark nearly opaque filters in them. Why couldn't I just put together new orange filters for the fixed in-body slots, and put black cardboard in the vanes so I can close it up and make it dark when I want to? Why wouldn't that work just fine?

Thanks.

[Luis-F-S]

Try it and see if it fogs the paper. There have been posts in the past on making the filters with Roscoe gels. L

http://www.largeformatphotography.in...ghlight=duplex

Bulbs:

http://www.topbulb.com/35w-low-pressure-sodium

[lenser]

The bulb man, Reno Nv. I bought a new bulb from them a couple of years ago for only $29.99. No idea if the price is still the same.

[StoneNYC]

Luis those are sodium bulbs not met curry vapor bulbs. I know people use the sodium as a substitute but isn't there a difference?

[Old_Dick]

Just took a look. Mercury vapour lamp (380-780 nm) , sodium vapour lamp is concentrated in the yellow part of the visible spectrum (around 580-590 nm)

[Jim Noel]

Unless your darkroom is very large you probably don't need all teh light the lamp can produce. In my 10x10' room I replaced the filters with pieces of mat board painted flat black in order to attenuate the light to a reasonable level.

[Old_Dick]

I used Rubylith as a filter, works great. I got the Thomas almost for free.

[EdSawyer]

These do take Sodium bulbs by design, and the price on them from good vendors is still about $30-35.

I think the upper vanes did have a different color filter than the lower filter windows, not sure if they were just for attenuation or further filtering or ?

in big darkrooms I have been in, they had one of these running wide open (vanes all the way up, just normal orange filters in place) with no fogging issues.

[HMG]

If you haven't used one, you're in for a treat. I was going to sell mine, thinking way overkill for my 8x8 darkroom. But I wanted to test it first. Hung it up, plugged it in, and it's been there every since. I made new filters with hardware store glass and rubylith. No issues with fogging.

[StoneNYC]

Just took a look. Mercury vapour lamp (380-780 nm) , sodium vapour lamp is concentrated in the yellow part of the visible spectrum (around 580-590 nm)

Thanks, can you help me understand, what spectrum of light does to print paper which is NOT sensitive to... Amber/red light but IS sensitive to other light colors, so yellow is (I thought) in the spectrum of "fogging" (let's use Ilford VC/MG type modern papers which prefer amber) papers.

And also let's deal with the light and how it "feels" in the darkroom. One of the nice things about the Thomas' over a red safelight to me is that my eyes handle it better, but amber is not yellow, so can you educate me on both the fogging and light output color in these terms? If you don't mind, thanks!