Durst Laborator 138 lens mounting

**Bob Wagner** · 1-Mar-2023, 16:57

If you know about mounting lenses on this enlarger I could use your help.
I recently obtained a Durst 138 with the lens board adaptor ring for 4x5 and 5x7 lenses. According to the manual I need a SEIPLA 75 semi-sunk lensboard for medium format and a LATUB tube for 35mm, or something that will give me the proper recess or extension of the lens. Looking around the internet I see various lensboards but often with slightly different names and no measurements. So, in order to buy or make what I need, I think it might help to know how much of recess do the SEIPLA and LATUB adaptors provide? The LAPLA board that fits has an outer diameter of 78mm or just shy of 3 1/16"
If anyone has a similar setup and wouldn't mind taking a couple of quick measurements, I would be much obliged

**ic-racer** · 1-Mar-2023, 18:38

Try to find the exact names. For example the 8x10 enlargers used either HOTUB or LARATUB recessed boards which both seem to fit fine on the L1840. But if you were to interchange them, the LARATUB board can touch and or break the negative glass on the L1840. The electric focus won't provide any feedback that you are cracking the glass.

**Drew Wiley** · 2-Mar-2023, 10:58

I simply had Jim Galvin machine me a custom recessed system when he was still alive. It nicely doubles in reverse position too if needed. No doubt others like Glenn Evans (Glennview) or the SK Grimes outfit could provide the same kind of thing.

There were two different outside diameter rings systems, which will both fit in the 138 turret; but the smaller diameter one, intended for a different enlarger series, will not fit tightly, and will not automatically center. It is tight enough, however, to prevent a perimeter light leak if the retaining screw is fully tightened.

**koraks** · 3-Mar-2023, 01:39

Bob, for what it's worth, I just took a decent image of a Latub and deduced the approximate height from it. I then drew something conceptually similar to the original Durst thing in 3D and printed it. I arrived at around 70mm of recess, which turns out to work fine. It was more of a gimmick since I mostly use a 75mm on the slightly recessed original Durst board for 35mm work. Since I usually print small, up to around 8x10", especially from 35mm, I like having a bit more space between the head and the easel. I'd suggest starting with the 75mm and then decide if you need a 50mm at all.

What Drew says about the diameters is correct. My boards are not the correct ones, but the slight off-center doesn't hurt in practice and there are no light leaks. Note that I only go up to 4x5" film size; the centering issue may be a problem when enlarging 5x7's.