• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Thomas Duplex Super Safelight

Matt York

Member
Allowing Ads
Joined
Feb 17, 2005
Messages
4
Location
Ohio, USA
Format
35mm
A question for those who have one, or who have used one.


I bought one of these on ebay, and it came with filters in the swinging
"door frame". These filters were red and had red tape around the
filter. I noticed too, however, another filter just below the swinging
door sitting in the 'framework'; in the unit body itself. This filter was darker and had yellow
tape around the edges.


I went on B&Hs web site and they have replacement filters, with
red, black, yellow, green and blue edges. It wasn't clear to me that
the filters that were in the framework below the door belonged there,
or were there for ease of shipping. So my questions


1) Are there supposed to be 2 sets of filters in the safelight; one in the door and one in the unit/framework?


2) If not, isn't it harder to control the light if there is no filter between the [open] door and the bare bulb?


3) From reading B&Hs site, it would appear that the yellow edge,
and then red edge, are the best for standard B&W work. Is this
true? What have you have you found to be best?


4) Any other input is appreciated.


Thanks
 
You need both filters. The yellow ones are for B&W printing, and the red ones for Ortho printing. As you note, the top filter that swings away throttles some of the light. I use mine completely shut, and still add a cardboard flap to further reduce the light. The Thomas safelight gets brighter after several minutes use, so wait to do a safelight test. I find mine very bright in a smaller darkroom (about 10 x 17 feet).
 
Are you saying that the unit has red filters in the base and yellow in the swinging windows? I have a Thomas sitting up in my darkroom but have not used it. I have a separate OC and a Red, ortho safelight I use. With the Thomas I would have to change the filters or are you saying you open the wings for one and close them for the other? The units are heavy, lights expensive, filters expensive, but really bright. I haven't had the courage to put it into use yet. After I bought it I wondered why I did, do I really need it?
 
Just FYI, I keep my ortho doors closed all the time. In my darkroom that's plenty of light (with the ortho filters lifted, I could read the newspaper). I do this mainly because I fog paper with them open and don't with them closed.
 
As Lee had pointed out as an idea, he has placed ruby lith in the filters to further reduce light output and spectrum.

I will be doing safe light tests with the new material this weekend.
 
The yellow-tape OC-type filters are in the base, and the red-tape red-ortho filters are in the openable flaps. I keep the flaps closed, filtering the light through both filters, and still the light is too bright. So I add cardboard flaps covering about half the openable flaps. With both filters, you should be able to use it for both regular paper and ortho. It is very bright, and you can not turn it on and off with a timer, because it needs to warm up. I sometimes wonder why I got mine, too.
 
I've heard so many things about the Thomas that it seemed to be the only one to buy. This may be a silly question, but what if I added another filter in the unit, essentially doubling it up?

I tried this and it appears that there is enough clearance in the unit to allow for 2 filters in the unit and the door (with another filter in the door) still closes comfortably.

Of course, that costs money. Am I just better off making a cardboard mask to reduce light output?
 
The yellow-tape OC-type filters are in the base, and the red-tape red-ortho filters are in the openable flaps. I keep the flaps closed, filtering the light through both filters, and still the light is too bright. So I add cardboard flaps covering about half the openable flaps. With both filters, you should be able to use it for both regular paper and ortho. It is very bright, and you can not turn it on and off with a timer, because it needs to warm up. I sometimes wonder why I got mine, too.
__________________
Eric Summerfield

Thank you, that's the most clear explaination and I really didn't know how to use it until now. Thank you Eric!
 
I bought a Thomas safelight off Ebay recently. Mine has yellow filters. Did a safelight test with Kentmere FP VC paper this weekend. I flashed the paper with the subthreshold exposure from the RH Designs paper flasher and then exposed the paper to the safelight at the average distance for 7-8 minutes. Major fogging. I had the windows of the safelight mostly open so it was very bright. I did not have time to test it with the windows down.

My darkroom is 8 x 16 feet and I placed the light in the far corner, near the ceiling, with the light bounced off the white ceiling. Will probably need to close the safelight windows to greatly reduce the light output. Too bad. It was so bright in there.
 
I have the opportunity to purchase a Thomas Duplex used at a reasonable price. It would be for my 6x12 darkroom (still under construction).

I've read the comments on wait time to reach steady brightness and that it may be too bright - at least with the doors open.

But is a lower watt bulb an option? As I understand, the standard Thomas-supplied bulb is 35w. I don't know if the Thomas bulb is proprietary (wouldn't think so but who knows). This site shows a number of sodium vapor bulbs with what I understand is the proper base, including an 18w:
Dead Link Removed

Any experience with using a different bulb? Does anyone know the specific bulb type (including base) required? I have not been able to find a manual for the safelight online.

Thanks.
 
LPS lamps require a ballast. I don't know if the 18W lamp will operate properly off a 35W ballast, but it's something you should check into before buying, aside from other issues. Likely someone else here on APUG will know about the ballast issues.

Lee
 
I have a Thomas in my 10'x10' darkroom. It is in the middle, close the 8' ceiling.

I replaced the filter in the upper gates with a piece of cardboard painted flat black. The yellow filters are in the unit near the light. When I print silver gelatin, the gates are open about 1-1 1/2". When working with alt processes the gates are wide open.

I have used them in this manner for about 20 years and never had a fogging problem.
 
I have red filters in the gates. I use my Thomas with the gates completely closed in a 6x12 darkroom and it's still plenty bright...though not as blindingly bright as with the gates open. The light it produces is still yellow, not red.
 
I purchased that 18w bulb--it does work in the Thomas (no, the Thomas bulb does not have a proprietary base), and I'm still using it almost one year later. But I didn't notice much difference on the light output. It was still too bright without cardboard shields covering about half the opening.
 

One would think that, with half the wattage, there would be a noticeable reduction in light. But at least the bulb is less expensive than the "correct" one from Thomas.

Thanks for the info.
 
I installed a Thomas safelight in my darkroom about a year and a half ago and can't live without it. I've never had any problems with paper fogging with graded or VC paper. I use mainly FB paper. I also leave it fairly open and my darkroom is about 12X18 feet, and not entirely light tight. The problem I seem to have now is the thing is making noise as though the ballast is going bad. Has anyone had any experience with noisy safelights or bad ballast? If it is a sign of the bulb going, I'm curios about other folks experience with alternative sources for bulbs. The Thomas safelight was manufactured here in Charlottesville Virginia, and the word is that the Thomas family is no longer in the business of making or selling replacement parts. For those who love their safelights, I would suggest picking up a back up or at least stocking up on a spare bulb as they will not always be around.
 
The bulbs are all over the place, look for a 35watt low pressure sodium bulb at like 1000bulbs.com or someplace of that ilk. They should be about $40.

I have one light that is starting to make noise, but I leave it on almost all the time. I've been running it for 10 years.

I actually have almost 8 of these things. People keep giving them to me. lol
 
thomas duplex safelight

How do you connect the end of the light to the net ? I can't use the electric small US pins on our European Electric net system .Do I need a transformer to let work the safelight or intermediair connectsystem to use the American pins on the Europe electric net .If I need a transformer ,where can I find it ?

thks

etiennedezutter@yahoo.com
 
Yes, you need a transformer to convert your 220 volts to the safelight's 110. If nothing else, check eBay for one.
 

Thanks for taking the time to do a test...

Well, there you have it. I thought the sodium vapor bulb was inherently safe...

Makes me wonder... Is your problem faded filters? Is it the extended spectral sensitivity of your VC paper (where maybe the Thomas would work great with Graded papers)?
 

That was obviously a older thread, but the observations are still valid.

Low-pressure sodium vapor discharge tubes have more than just sodium in them. They also have small amounts of neon and argon intentionally introduced during manufacture. These help with the initial striking of the lamp. It's called a Penning mixture. This mixture introduces additional emission spectra from the blue and green portions of the visible spectrum. (See here for a real-world illustration, 4th entry down, note the blues and greens.) These additional spikes are what is actually fogging the paper.

If you have access to a Thomas Duplex try starting it up and letting it stabilize. Then remove all of the filters so you are looking at the bare bulb. Find an old CD/DVD disc. Use that disc to reflect the light from the bulb and look closely. The disc will act as a poor man's prism. In addition to the overwhelming orange sodium light you will also see much fainter, but still significant, pure bands of both blue and green light. Once you know what you are looking for, repeat the observation with the originally supplied filters for b&w back in place.

The solution is to add an additional (inexpensive) layer of Roscoe Roscolux #19 Fire filter. It's a theatrical lighting item. It will remove all of the extraneous blues and greens while passing about 35% of the correct sodium D-line emission oranges. (See the filter technical data sheet here.) You lose about two-thirds of the "good" light in order to remove all of the "bad" light. But the Thomas is so darned bright to begin with that the loss is usually a good thing in a smaller darkroom.

The Thomas Duplex is no longer manufactured. However, if you still wish to buy a new one of this type of safelight you can (as of the time of this post) still do so from the Sebastian Darkroom Products division of California Stainless Manufacturing. Click the following link to see a description of their OC-1012 sodium vapor safelight. It looks almost identical to the Thomas. California Stainless is the OEM manufacturer of many of the items offered by Arkay.

Ken
 
Last edited by a moderator:
Bill, I found almost an identical experience to that described by Ken with bright orange LEDs. I did the same test with a CD, got green and blue spikes. I tested both a Lee lighting gel 19, fire orange, and a Lee primary red. Orange was safe to just 4 min, while red gives me 15 min safety with MGIV WT. Michael 1974 has been very helpful by sharing his filter experiences when he was building his LED safelight. I am delighted with mine now.
 
And I had the same problem with 635nm red LEDs. The CD/DVD test showed small pure blue and pure green spikes that led to unexplained fogging. The unaided eye could not see these. I then tried a single thickness of standard Rubylith as the filter. That did the trick. My tested safe time under the red LEDs (for both Ilford MGIV FB & RC) went to over 60 minutes.

Ken
 
You must log in or register to reply here.
Menu
Log in
Register