Curious case of enlarger lenses

Mrtony4x5 · Mar 11, 2018

Hi I'm diving into the world of darkroom printing
Getting a m800, beseler 23c dichro, omega d5
Im curious about how lenses are mounted on boards. I hear it's mounted with a retaining ring, some are directly screwed on the the board with threads, please help me out here
Thanks

mnemosyne · Mar 11, 2018

I can only answer for Durst and other European enlargers, but I am sure someone will add info for Beseler and Omega.

Normally enlarging lenses are thread mount, since ca the 1970s the standard mounting thread size for small and medium format enlarging lenses has been 39mm. Only large format enlarging lenses (focal length 150mm and up) have larger mounting threads. In that case, the actual size can vary considerably depending on make and age of the lens.

The standard Durst flat lensboard for the M800/M805 should be a LAPLA (metal) or SIRIOPLA (same in plastic) followed by the number that indicates the thread size in mm.

Earlier enlarging lenses (1960s and earlier) have smaller threads and less uniform thread sizes (M32.5, M25 etc.). I would recommend not to bother with such older lenses, unless you get one for free in clean condition and complete with mounting hardware. While they were fine in their day, a lot of them suffer from age related problems nowadays that would require service (cleaning/repair), which is not economically worthwile as newer/better lenses are so affordable.

You should download a copy of the M800 manual (should be available online) that will answer a lot of questions and name the relevant accessory parts.

Svenedin · Mar 11, 2018

Some enlargers use mounting rings. My Kaiser System V enlargers use such a system. It is a standard M39 thread ring that you screw the lens into and then mount that ring using a quick release system onto the lens board. This has the advantage (over screwing directly into the lens board) of ensuring the aperture window on the lens faces forward where you can see it. There are different rings for different focal length lenses.

bdial · Mar 11, 2018

Most Beselers I've encountered have lens boards that are not threaded. This is true for a lot of Omega enlargers too. Retaining rings are available without too much difficulty. Plus, many enlargers on the used market come with a lens or two, so even if the supplied lenses may not be what you prefer, it will have the retaining rings if they're needed and you can easily refit other lenses that suit you. Another wrinkle is that while most enlarging lenses have 39mm threaded mounts, some are larger, particularly some of the Schneider lenses. That's an area where an unthreaded board may make life somewhat easier, since making a 39 mm hole bigger is easier than making it bigger and threading it.

AgX · Mar 11, 2018

Svenedin said:
Some enlargers use mounting rings. My Kaiser System V enlargers use such a system. It is a standard M39 thread ring that you screw the lens into and then mount that ring using a quick release system onto the lens board. This has the advantage (over screwing directly into the lens board) of ensuring the aperture window on the lens faces forward where you can see it.

Otherwise one can shim the lens to get the aperture window at the right position.

Svenedin · Mar 11, 2018

AgX said:
Otherwise one can shim the lens to get the aperture window at the right position.

Yes but this is not that easy. I have done it and it never quite works when changing lenses

Mrtony4x5 · Mar 11, 2018

So the m39 threads are either straight to the board or will have a retaining ring? Same goes for larger diameters?

Svenedin · Mar 11, 2018

Straight to the board in which case some kind of shim or a retaining ring that you can rotate to your satisfaction when mounting

mgb74 · Mar 11, 2018

bdial said:
Most Beselers I've encountered have lens boards that are not threaded. This is true for a lot of Omega enlargers too. ...

My experience as well but I have seen, on occasion, threaded Beseler boards. IDK if they were factory threaded. As to Omega, all the early D series I've seen (DII, D2, D3) are not threaded. Some of the later lens plates I've seen are threaded.

tedr1 · Mar 12, 2018

A little bit of history.................enlarging lenses with 39mm threads became a common type, especially with European and Japanese makers, in the 1960s and 1970s and later. The enlarger lens mounting method for European and Japanese enlargers made after this time commonly use 39mm threads, sometimes with a removable lens board, sometimes not. Some lens boards are plain 39mm hole and need a retaining ring. Some are 39mm thread and need no ring. There is an advantage to the ring method, the lens may be rotated so the aperture window is facing the operator. When the lens is changed the panel (if there is one) stays put.

US lenses were made with a wide variety of thread diameters and pitches and it was common to mate each lens with its own panel and ring. It is common to find older US lenses that are not 39mm types. Finding the thread details and a matching ring can be a problem.

Larger lenses (135mm and over?) are rarely 39mm, the hole is too small.

BobMarvin11225 · Mar 14, 2018

Some Omegas, like my B-8, or the larger D-2, use lens discs, mounted onto various length cones [or, sometimes, flat boards]. Most discs are unthreaded and require retaining rings [AKA jam nuts], but threaded rings are also available [at least in 39 mm LTM]. I use threaded discs for lenses [like my 60 mm WA Companon] that protrude inside the enlarger, preventing sliding the assembly into place.

voceumana · Apr 1, 2018

Note that Nikon and some others made an extension ring with 39mm threads. It was used to extend the lens out from the lens board by a few mm--15mm on the one I have, but others may be found. It can be used when mounted to a non-threaded lens board to provide a threaded fitting to which different lenses can be readily attached and removed without fussing with the retaining ring. Of course a retaining ring is needed to mount the extension to the lens board.

Works fine as long as the extra distance between the negative and lens is not a problem. And, it is no longer in production, so you have to look on the used equipment market. I found one made by Canon with 25mm extension.

The 39mm threads were used on screw mount Leica lenses (and others) so look for camera screw mount extension tubes as well as for enlarging lenses.

winger · Apr 2, 2018

bdial said:
Most Beselers I've encountered have lens boards that are not threaded.

My Beseler 23CIII came with a threaded lens board. I don't actually know if the shop where I bought it did that themselves or if it was OEM. But it was a brand new enlarger in 2002-ish. My much older Beseler 45MX uses a retaining ring.

faberryman · Apr 2, 2018

My Beseler boards required retaining rings. But I know some are threaded.

John51 · Apr 2, 2018

Some older enlarging lenses I've seen for auction are basically a tube, no thread at all. How do they get mounted?

Curious case of enlarger lenses

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