Durst 1840, 184 and 138 enlarger lamps - NEWS !

[jps]

New OPAL light bulbs for Durst large-format enlargers.

Durst used to provide 4 versions of OPAL bulbs for their enlargers with condenser units. They were large and rounded, designed to provide an even illumination of 5x7 and 8x10 negatives. Available in 200W, 300W, 500W and 1000W versions, these bulbs were produced by Thorn and Atlas, but have been discontinued for 25 years. These bulbs have now become rare, as stocks have gradually depleted around the world.

For this reason, alternatives have emerged, Jensen in USA sell a modification kit and several postings on the large format forum shows alternative light sources being incorporated into the enlargers.

Personally I have always found it a shame to modify these beautifully crafted enlargers and prefer to use them as intended. To investigate the possibility for obtaining new bulbs, I contacted the Dr Fischer Group, a specialist lamp factory in Germany and one of the last factories in the world that still produces opal bulbs for photographic enlargers. To me they have expressed interest in producing a limited run of large-format light bulbs, which will allow everyone to restock their supplies.

As this is a niche product they will likely only produce one version, I have suggested the Durst Opal 500W as a good compromise between light-intensity and heat production.

I only have one original 300W bulb available and which I will provide the factory as a template, but in order to get the new lamp as close to the original as possible, I ask anyone who still has original DURST OPAL bulbs in stock, to measure the height and width and upload these measurements to this post (together with data printed on the bulb). The data will allow the factory to compare several bulbs, rather than just copying mine. Detailed images may also be helpful. If any of you also want to send them a bulb for examination, I can provide their shipment address.

 

[Hilo]

Nice work JPS !

I have a wall mounted Laborator 1000, which takes 200W bulbs. When you install a heat glass between bulb compartment and negative, it could use 300W and perhaps 500W. Since I could not find the heat glass, I installed a small fan into the lamp head and everything seems to be ok. I have three or four spare bulbs, but need to check which ones they are.

If Fischer would consider doing two variations, I would suggest 300W and 500W.

For my Focomats 1C and 2C I have been using Fischer bulbs 150 and 250W. I bought an extra 10 bulbs about 10 years ago, and they are still waiting in the box . . . (I print daily . .)

Michael

 

[Hilo]

Ok, I had a look in my darkroom. I have three 200w bulbs, one made by Atlas and two made by Thorn. They are identical. Largest diameter is 11cm and the length is 18.5cm. When I put a tape around the largest part of the bulb it measures 34,5cm. All these sizes are just kind of 'looking and guessing'

This is what it says on the lamps:

Atlas: P 3/15 ATLAS 220V - 200W 82 (this 82 very small)

Thorn (left in picture) 220-230V 200W P 3/15

Thorn (right in picture) P 3/15 THORN 240V 200W

 

[ic-racer]

What measurements do you need. I have a couple Thorn HX27 2000W.

 

[jps]

Great info Michael (Hilo), your 200W width measurement (11 cm) and circumference (34.5 cm) are identical to my 300W, but my bulb are a few mm higher than yours.

From the Durst literature I seem to remember that a bulb needs to be 11 cm wide to evenly illuminate a 10 x 10 inch negative field.

I agree with your choice, a 200W or 300W and a 500W seems a good combination. The 200W - 300 W can be used in the 1840/184 condenser with a heat filter, while the 500W and 1000W requires ventilation.

If anyone else has measurements/images, please upload them. This is our chance to get new bulbs, which will allow years of printing.

Does anyone have Opal 500W or 1000W?

IC-racer .. Your Thorn HX27 2000W (DURST COLAMP 2000 N) are tungsten halogen light for the Durst CLS 2000 light source. Durst provided both a 1840 condenser unit (using bulbs) and the CLS1840/CLS2000 cold-light source using halogen light. As these lamps are also very difficult to find, I will ask Dr Fischer if they could consider a limited run of those as well.

 

[Hilo]

JPS

You think Fischer would do both voltages? 110 and 220?

Where are you anyway and where is Fischer located? I am in The Netherlands.

There's also someone here who has promised me one, or a couple, of these bulbs. It is one of those stories that take time, but will actually happen. I see the person this coming week and will ask if he knows how many watts his bulbs are . . .

If these Durst bulbs live as long as the 150w bulbs I use with the Leitz enlargers, I should probably not worry at all . .

Michael

 

[Hilo]

I measured the length of the bulbs more exact: 18.8cm . . . not easy to be precise!

 

[Luis-F-S]

Hi, I can send a Thorn 300 W bulb if that helps as long as I can get it back. Let me know. They're hard to measure, but I can try when I get home. It would be great if you could get them made for 125 volts so it would be a long life bulb and in 300W or 200W as the 500W is way too bright IMHO for 5x7 on the 138. I'd be interested in say five (or possibly more depending on cost) of the 200W or 300W, or a couple of 500W if that's what they make, when if they become available. I always wished I had bough several of the 200 W bulbs, as I typically would dim down the 300 W one both to extend the life and get longer exposures. The 500W as you know produces much more heat and I would have to dim it much more than the 200 or 300W in order to use it. That changes the light temperature which is another issue.

Also, I think some folks are getting confused with the 1000W bulb, I believe you are referring to the incandescent bulb, not the tungsten halogen one. L

 

[jps]

I have send my Thorn 300W bulb to the factory yesterday. They have promised to examine it and provide feedback.

I will keep you posted..

 

[Luis-F-S]

I think the trick will be in the thickness and evenness of the opal coating of the bulb. Durst used to reject a lot of bulbs due to coating imperfections. Thin coatings have been an issue with some of the "replacement" bulbs tried by different folks. I know the G40 bulb for instance has a much thinner coating than my Thorn bulbs. L

 

[JG Motamedi]

Thank you for doing this. I would be very pleased to buy a lifetime supply of bulbs, if I can afford to do so.

I have only one original bulb, a 500W Thorn bulb. It is the same size cited by others, 11cm x 18.8cm, and is way too bright and hot to use in the 138S. I normally use a 150W G40 bulb, which is an acceptable but imperfect replacement. A new 200W (maybe 300W) bulb with heavy coatings would be wonderful.

 

[jps]

The coating thickness and evenness was an issue unknown to me.. this is brilliant information. Thank you Luis!

My hope with this posting was that we could share our collective user-knowledge regarding these bulbs, which would allow the factory to produce the best possible product.

 

[miha]

My Durst CE1000 came with a Philips Photocrescenta 250W bulb. It's a 4x5 enlarger only but the bulb which is still available new measures 12cm x 6,5cm and povides even illumination with a condeser head.

 

[Hilo]

My Durst CE1000 came with a Philips Photocrescenta 250W bulb. It's a 4x5 enlarger only but the bulb which is still available new measures 12cm x 6,5cm and povides even illumination with a condeser head.

My enlarger is a Durst Laborator 1000 4X5, which is mounted on the wall. With larger prints (20X24 / 50X60cm) the bulb you are talking about does not give me even illumination for sure. With smaller prints there is still a problem, but less so . And the large Durst bulbs do give the correct illumination. Maybe this differs per enlarger model.

 

[miha]

It's possible. I go up to 30x40 cm only and the illumination is perfectly even in my case (CE1000, double condenser system).

 

[Hilo]

I received three more 200 watt bulbs, two have the same info which is slightly different from the ones I listed before:

P 3/15 Thorn 220 - 230 V - 200 W ( compare to my previous post) The size and shape are the same

The third bulb is quite different:

- The shape is more classic (less like a pear)

- the length is more, it is about 20cm

- the info is on the round top of the white opal and reads: RADIUM DURST A61 220V 200W R236

Pictures attached:

1) The DURST branded bulb
2) The info of 1)
3) comparing with the Thorn bulb

 

[railwayman3]

Slightly OT, but I bought some of the special bulbs (with an offset filament) for the Minox sub-minature enlarger a while ago, and these were being made (at least at that time) by the Dr Fischer factory. Perhaps worth asking them if anyone should need spares of those bulbs.

 

[jps]

Unfortunately, I have disappointing news, regarding the light bulbs.

I have received the following message from Dr Fischer Group

"We regret having to inform you that we are not able to reproduce this lamp, due to a missing component which we are not able to source.”

From my initial communication with the factory, It was my impression that new bulbs were a possibility. Unfortunately this is no longer the case.

Thank you Dr Fisher for trying - and thank you everyone for the information you uploaded.

 

[Hilo]

JPS, indeed that is disappointing !

Thank you for trying, that is very good from you !

Michael

 

[ic-racer]

I'd not be limited by the globe of the lamp. I'm not the first one to realize that you only need to project a disk through the condenser system (does not need to be a globe). For example look at the setup of this Philips condenser enlarger from the 1970s. It uses quartz halogen lamps and shines them behind this diffusion disk which illuminates the condenser system via a mirror (not shown).

 

[Luis-F-S]

Unfortunately, I have disappointing news, regarding the light bulbs.

I have received the following message from Dr Fischer Group

"We regret having to inform you that we are not able to reproduce this lamp, due to a missing component which we are not able to source.”

Did he ever say what the component they could not source was? Seems odd as it should just be a simple bulb for someone who specializes in such items.

 

[Ginette]

Probably a radioactive element!

 

[Serg Lavrenchuk]

He had to find a solution for missing Durst Colamps 2000 and reflectors (not supplied with equipment) for Durst enlargers that we bought from one b(d)ad guy in Hillsboro.

After 2 years of using in practice, I think that reflectors made for us to copy few durst ones that we could get came out good.
We have ordered some few dozens of CLS1840/2000/2501/2606/Optromat reflectors as that was minimum order to make.
So if there would be a guy who can't find one for substitute his worn we might sell some from our treasure box.

The lamps that we made to copy Colamp 2000 came good for Horizontal enlargers but need to be more tested in vertical.
They came out a little bit more W than original 2000W (1.7 ohm VS 2 ohm) and some 100-200K warmer on the same settings.
One lamp is working already for a year in our horizontal machine. In vertical in factory tests, their couln't show even 100H lifetime due to filament bending down and breaking.
We made test run of 10 lamps and now 1 is down in 10-20 H run (horizontal) and the second one going for a year (horizontal) after we dropped V to 217V instead of 228V default on the pcb board.

These lamps make some yellow snuff at the inside of the glass from filament burning with time. But all those evaporations condensed on the "cold" part of the lamp (one that is outside reflector) so working part is clear.

With these DIY durst reflectors and "colamps" I could get 0.00-0.01D delta in over light field (measured with ZoneMaster photometer) over the 150-170cm board with some 150mm 1ev-stopped lens.
So they are enough to be a better option then "tomorrow" that never came.

Will try to make comparison pictures soon.

Forgot... I still have some hesitations if we used right kind of reflector coating.
I heard from an engineer that this reflector coated with some kind of coating that reflects visible spectrum forward but transmit head spectrum backwards to protect dichroic filters.
So it is so and to what extent, and were our reflectors coated right I can't yet check with present means.

Serg

 

[ic-racer]

...we might sell some from our treasure box...
So it is so and to what extent, and were our reflectors coated right I can't yet check with present means.

Looks better than my worn-out reflector on the LEFT of this picture. I'd be interested in a new one or interested in getting the worn-out one re-coated.

 

[Serg Lavrenchuk]

I think that 300usd would be a fair price?
That would give me a chance to gather some bucks to make some new ones one day.
Materials cost me 100 per one but if selling for less I wouldn't be able to produce a new run before going off own reserve.

Not like I wish to bribe you guys.