Durst L1840 Enlarger 8x10 10x10--Everything you wanted to know...

[neil poulsen]

. . . An additional note on the range of the Rodagon. As you may know, there is a point where an enlarging lens can no longer form an image. With the 300mm Rodagon, this point is just below the 1:1 magnification level. I tried to do some 1:1 prints and the focusing at this level is very strange. It is difficult to get it in focus, because it is right on the verge of the point where focusing is not possible. I was able to make some 8x10 prints, but compared to contacts, they were clearly inferior. This does show me that to make 1:1 prints, a process lens would be superior.

On rare occasions, a 240mm Apo-Rodagon process lens shows up on EBay. Made in about the 60's (I'm told), its optimum magnification is 3:1 to 1:3. It' optimum aperture is f16. It was made to have a wider field than a standard Apo Ronar. These lenses were also made in a 300mm and 360mm focal length.

[Curt]

It would take some time to list my enlarging lenses. In the way back I bought them new and still have those. I have a Rodagon 240 mm that's excellent, a Rodagon 150 mm in a Durst cone, an Apo-Gerogon 210 mm f9 that fits in the same cone but is a process lens and not suited for enlarging, a Componon 180 mm f5.6 enlarging lens with no click stops, the silver body type. EL Nikkor 150 mm 53 mm flange, EL Nikkor 105, 75, 50. Componon 75 mm, 50 mm. Apo Nikkor 360 mm, 300 mm. And others...

My intention was to use the 240, a 150, and a 105 or 75 for 5x7, 4x5, medium format sizes respective. I have a glass negative carrier that's new. It was designed by a company for the Durst enlarger. It has small diameter stainless steel rollers and an additional partial lift system for what appears to be five inch arial roll film. It's heavy but precise. It was intended to be used with the enlargers built in masking and mine works 100%

I have a very clean lightly used 138s condenser head with two 240 condensers. The bellows is clean and in great condition. Everything is intact and working as it should.

[Curt]

So, getting back to Curt's original post. As we can see, Curt's enlarger has a fixed turret, it is not removable like the later model Durst enlargers. So, lets get back to the original problems. 1) Poor alignment and 2) Inability to mount some lenses easily

In terms of Poor Alignment, I would ask how you are checking it and how far off do you think it is? I know on my enlarger it may be possible to adjust the entire lens stage at the area where the focusing gears mesh with the stabilizing rods.

In terms of lenses, I concentrate on finding good examples of the original DURST branded Schneider Componon lenses that fit the enlarger and not use any oddball lenses, even if you already own them. It will likely be more trouble thhan it is worth, especially since enlarger lenses are pretty inexpensive these days.

Here's my latest update. There is no solution other than replace the entire lens stage. With the early design of the fixed Tripla I'm cooked on that one, at least in the lens mounting area.

If I wanted to break from the original design I could go rouge and design something on my own. Bring me your designs. I haven't tried but I think the six screws are all that holds the tripla holder works on.

Live update: I just went up and examined the areas of interest. The lens stage. The six screws hold the lower bellows on. The lens stage is a machined one piece part. I can see how it's removed. Besides the six bellows mounting screws there is one point of attachment. It's at the rear where the one piece lens stage is round. That round projection is fastened from behind so it can rotate giving the tilt feature to the lens. The degree pointer is also attached and a permanent machined slot for the zero detent. The lens stage is a separate piece in the lens focus mechanics.

A new lens stage could be machined and welded from aluminum plate and a short piece of thick walled tubing and any design for lens mounting would be possible. An adjustable lens mount with any shape boards. It's a fair amount of machine work and design. In my case I'm probably going to keep the original equipment as is and work at getting the 240 mounted to a disk for the Tripla.

I'm not even sure I want to invest the money in an adapter. I'll make one.
That's aprox. where I am now. I thought it might be a bit easier but like most things it's often not.

[ic-racer]

Not sure I still understand the initial problem. Is the Tripla wobbly? Or is it just out of alignment?
Also, is this an 8x10 conversion? What are using the 240mm lens for?
I'd think the Apo-Gerogon 210 mm would be great for 5x7 enlarging, what kind of trouble was it giving?

[Curt]

The fixed Tripla is older, worn, and not adjustable. Its design predisposes it to misalignment without a built in correction.

It's not an 8x10 conversion though I was heading in that direction at one time when I bought the 240 mm but not now.

The 240mm is the largest lens recommended for 5x7 and is on the enlarger heads specification chart. (240 mm lens with top condenser 240 and bottom condenser 240.) I know it also covers 8x10.

The 210mm Apo-Gerogon; it's a barrel process lens with a maximum aperture of f9. It fits in a 50 mm Durst extended cone adapter which I have. Focussing would be dark compared to 5.6 enlarging lenses. There are no aperture click stops and no lighted dial. I can't find any lens specifications on the Rodinstock home site, the only information is anecdotal Internet quality and a Wiki link that indicates the source was ad like. My search was all variations of: rodenstock apo- gerogon 210mm.

The Schneider Componon 180 f5.6 isn't an "S" and is the older chrome barrel with no click stops and that vintage didn't have a lighted dial.

[gary mulder]

The fixed Tripla is older, worn, and not adjustable. Its design predisposes it to misalignment without a built in correction.

It's not an 8x10 conversion though I was heading in that direction at one time when I bought the 240 mm but not now.

The 240mm is the largest lens recommended for 5x7 and is on the enlarger heads specification chart. (240 mm lens with top condenser 240 and bottom condenser 240.) I know it also covers 8x10.

The 210mm Apo-Gerogon; it's a barrel process lens with a maximum aperture of f9. It fits in a 50 mm Durst extended cone adapter which I have. Focussing would be dark compared to 5.6 enlarging lenses. There are no aperture click stops and no lighted dial. I can't find any lens specifications on the Rodinstock home site, the only information is anecdotal Internet quality and a Wiki link that indicates the source was ad like. My search was all variations of: rodenstock apo- gerogon 210mm.

The Schneider Componon 180 f5.6 isn't an "S" and is the older chrome barrel with no click stops and that vintage didn't have a lighted dial.

If it was mine I would just put some bolts through it and fix the rotating part. Maybe some shims. Giving up the rotating feature and gaining precision.

[ic-racer]

The 210mm Apo-Gerogon; it's a barrel process lens with a maximum aperture of f9. It fits in a 50 mm Durst extended cone adapter which I have. Focussing would be dark compared to 5.6 enlarging lenses. There are no aperture click stops and no lighted dial. I can't find any lens specifications on the Rodinstock home site, the only information is anecdotal Internet quality and a Wiki link that indicates the source was ad like. My search was all variations of: rodenstock apo- gerogon 210mm.

"APO-GEROGON / APO-GEROGON S / APO-GRAPHIGON: These lens systems are designed for use in compact process cameras where the short original-to-film distance calls for wide angles of coverage. Angles vary from 70° to 78°, with reproduction scale ranges from 1:5 / 1:1 to 1:3 / 3:1."

Seems like that would make an excellent enlarging lens.

[Curt]

Since the 210 mm Apo-Gerogon fits in the same adapter as the 150 mm Rodagon I can put it in at any time and see how good it is. I found and mounted my 150 El Nikkor in a 53 mm adapter. A custom adapter would have been expensive.

[EdSawyer]

"Apo El Nikkors are specified two stops down"

Actually Drew these are spec'ed as being best wide-open. I recall reading that from more than one source, including Nikon's own brochure.

Usually 1 stop down is the best for most enlarging lenses, sometimes even less than that. Ctein had some data on that in his Post Exposure book.

[Drew Wiley]

Ed - depends what you were doing. I have the brochures, and there was a bit of evolution
within the Apo El Nikkor series. Remember, they were pushing the 105 for 35mm film use,
even though it was suitable for larger formats; but the ideal aperture would change relative to format. Largely overkill, however. Ordinary Apo Nikkors are ridiculously sharp and true apo if you don't need the extra speed. And contrary to the traditional lore, they top out around f/ll (not f/22). I sometimes use relatively long enlgr lenses
wide open for small format - a trick which would be less than ideal for the "normally" recommended diagonal. Apo El's are still being mfg, but only fixed aperture for industrial
applications. Mitutoyo has some similar offerings. I've done mtns of enlgr lens testing
myself - don't need second-hand opinions. But can't afford (and don't need) an Apo El.
Some of them are just damn heavy anyway and would deflect the lensboard on the typical
enlarger.