Questions about Durst 138 S opal or halogen lamps and format masks

[Mark J]

Are the 300W bulbs still available ?

Sorry, I read a bit more and see that Larry commented in some detail about this.
Are the smaller bulbs easy to find ? If i get one of these, I will be doing a lot of 6 x 9cm , with some occasional 5 x 7" .

[Larry Gebhardt]

Mark, I haven't seen any larger enlarger bulbs for sale in a while. I picked up some 500W GE 302 bulbs before I built the LED head, so around 2013. At the time topbulb.com was selling them, but I checked a while ago and they were no longer available. These are roughly 4" vs 4.5" for the Durst opal bulbs, so not quite as good for 5x7 coverage, but they do work. I don't know what the situation is in Wales where I assume you need 240V bulbs.

One option is to use a reflector bulb with the lettering scratched off. That is pointed at a sheet of opal glass in the heat absorbing glass carrier. That does work well and gives you even coverage with a decent amount of light. I don't know if acrylic or polycarbonate is up to the temperature since opal glass is getting hard to find as well.

[Mark J]

OK thanks. I see the original ones are definitely in short supply and going for silly money.
What kind of reflector bulb would that be ( for guidance ) ; yes I will need a 240V version, but will also find out what the seller is offering with this, first.
Is the lamp stage adjustable enough to get smaller lamps into a centralised position ?

I feel like I need to pump you for as much info as possible .... ! :
Is a 300W bulb OK for limited enlargements ( up to 3x ) from 5 x 7 ?
Do the filters in the drawer have to be Durst filters or can you adapt ilford gel filters ( assuming heat filter in place ) to the carrier ?

I am fairly resourceful and have some friends who can do machining and solve problems. i have just been in an out of my small darkroom several times with a tape measure today, and reckon that I can just ... just ... fit this beast into my small darkroom, though it will require some cut-outs in three shelves to allow the column to fit closer to the wall to make it work.

[Larry Gebhardt]

The condenser light stage is very adjustable. You can raise it many inches, move side to side and back and forth all from the tube that sticks down from the bottom of the enlarger. There are two bolts that stick up vertically and those have nuts that hold the lamp holder to the carriage. To use a reflector bulb you need to make an L shaped piece that can have a ceramic light socket attached to it with holes spaced for the bolts mentioned above. It should be really easy to build with aluminum angle stock and some bar stock from a hardware store. Someplace I have a version I bought from an ebay seller when I was trying to find a decent bulb solution. His lamp was just a flood light with the printing sanded off. I think 150W. I'll see if I can find the box it's in and snap a picture.

The filters can be Ilford filters and they must be about 100mm square, so cutting down larger 6" ones is needed (the opening is 3.5" square, but you need extra room for it to fit easily). Until you mentioned the filter drawer I forgot you could put a sheet of diffusion plastic in there behind the filter (so sandwiched between the head absorbing glass and the filter). That should protect it from melting.

A 300W bulb should be plenty for that size enlargement, and probably better than a 500W bulb unless you like really short exposure times. The 150W reflector bulb was also plenty bright since all the light was directed towards the lens.

[dsphotog]

In the US 120 volt G40 decorative bulbs are still available. I've used 100 and 150 watt for prints with 5x7 condensers.

[Mark J]

Thanks for all the information - this helps a LOT .

[Mark J]

Well, I took the plunge and just bought myself 75kg of Italian fun. I might start a thread on it when I get it back to the house. A trip to Oxford & back is the first step.

[Larry Gebhardt]

Nice. Be careful of the springs when you take the head and baseboard off. Raise them to their top positions before you remove weight or tip the columns.

[Mark J]

Thanks for the tip. I was wondering about that kind of danger you get from clock springs - but worse !
I believe that the seller has packed it up for transit, so I await to see what re-assembly is required.
I have all the condenser lenses to do 5x7, 4x5, 6x9cm and 35mm, but will need to spend some more to get the right lens mounting panels and adapters.
There is an Osram bulb and another, but left the exact details to review when I get the parts.
Not sure about the film holder, it's the 138, it has the glass ( I may get the lower one coated ) but not the adjustable masking strips.

It kills 2 birds with one stone, ie. that i can print 5x7" for the first time, but I have recently wanted to try condenser to see the tonality.

[Mark J]

It's quite big, isn't it ?
;o)


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