Thomas Duo Super Safelight question

jstraw · Nov 15, 2006

A Thomas is one bright mofo...this is a given. I've come across a couple of things lately that have me wondering... the admonition to extinguish safelights while making measurements, from RH Designs...and a discussion about some safelights fogging AZO and similar high-silver papers.

My question is this, since my safelight will not be controlled by my RH Designs timer, and I don't wanna turn it off for sensitive papers, is it safe to rely on just dropping down the red, ortho filters during those times?

lee · Nov 15, 2006

I have never seen the Thomas bother Azo. In fact, Michael Smith says they have one in their darkroom that they leave wide open all the time while printing. I have heard that the Thomas might bother Forte PWT but I have never seen any fog. It may be how big is your darkroom. Mine is about 12.5 feet square and my safelight is across the room. I would not let rumors stop me from buying a Thomas.

lee\c

Lee L · Nov 15, 2006

I worked for a year in a darkroom that was about 16x24 ft with high ceilings, and the Thomas with vanes open would give me some fog on Kodak Polycontrast Rapid RC II and III with less than 3 minutes of exposure and a closed roller transport processor, so I used it with vanes closed. Of course that's not Azo at your place, but it would probably be worth the short time it takes to do a good test. One thorough one is at: http://www.kodak.com/global/en/professional/support/techPubs/p255/p255.pdf

Lee

pentaxuser · Nov 15, 2006

Is the Thomas a sodium based light like the DUKA.? If so the problem is that switching it off gives problems of non safe lighting until it warms up fully again. Certainly true with colour paper. Not sure about B&W.The DUKA actually goes through colour changes as it reaches correct temperature.

The DUKA can be internally shielded by a lever but not entirely cut out. If Thomas bulbs are sodium and anything like the cost of DUKA sodium lights then it is an expensive safelight for B&W. I'd be inclined to swop to a normal safelight like the Ilford, Kodak or Paterson which can be switched off instantly and cheaply.

Hope this helps

pentaxuser

jstraw · Nov 15, 2006

My Thomas is very close to both my enlarger and sink. I will do some fog tests with the vanes closed and open.

jstraw · Nov 15, 2006

http://www.kodak.com/global/en/consumer/products/pdf/k4.pdf

"How Safe Is Your Safelight?"

Saganich · Nov 15, 2006

I've had my eye out for a thomas but am glad I didn't buy one specifically because of the RH Design Zone meter which require all lights be off when making measurements. This would be true of any densitometry performed with your enlarger. The duplex takes time to power up. I also have to shut the safe lights for burning/or dodging with a grade 5 filter. Rare as that is.
Chris

Robert Hall · Nov 15, 2006

Mine fogs Forte quickly. I can print in full (safe) light with any of the ilford papers. (kind of wierd it's so bright.)

For my foggable paper, I open it half way and throw a towel over the half that points towards the enlarger.

I also have a large red light that I keep over by the developing tray for when I do lith since it takes so long. It helps quite a bit.

I also have set up the darkroom that I don't get reflections off important walls and my body shields the paper while working on it.

jstraw · Nov 15, 2006

Robert Hall said:
Mine fogs Forte quickly. I can print in full (safe) light with any of the ilford papers. (kind of wierd it's so bright.)

For my foggable paper, I open it half way and throw a towel over the half that points towards the enlarger.

I also have a large red light that I keep over by the developing tray for when I do lith since it takes so long. It helps quite a bit.

I also have set up the darkroom that I don't get reflections off important walls and my body shields the paper while working on it.

Will it fog Forte with the vanes closed so that the red filters are in use?

Robert Hall · Nov 15, 2006

It sure will!

reellis67 · Nov 15, 2006

They use one of those in the darkroom at work (gang darkroom) and it is BRIGHT in there. The room is big, maybe 30' long by 12' wide and it will fog paper in a very short time. They told me that they had to use multiple filters to drop the light levels somewhat, but they are not really very knowledgeable about such things. I did check the bulb for them and it was correct (big $!), and the filters didn't appear to be faded, but man was that thing bright. All of the prints the kids were making were fogged out until they added the extra filters - even now the safe time is shorter than most student printers know how to deal with.

- Randy

Thomas Duo Super Safelight question

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