Lens to enlarger attachment and other questions

I currently use an Omega Prolab enlarger in a community darkroom, and have acquired a second one in anticipation of setting up my own darkroom at some point in the future.

I have recently picked up a couple of enlarging lenses, as I don’t wish to rely on those in the darkroom, but getting the lenses seems to be easier than getting the appropriate attachments.

The lenses I have are a Schneider-Krueznach Componon-s 5.6 150 and an El Nikkor 5.6 150.

The Omega Prolab has a plate that slides into the bottom of the head with an oval shaped drop that has two thumbscrews. The best lens attachments match that oval shape and have large enough holes that fit right over the widest part of the thumbscrew with small slots to the side. You push the larger holes over the widest part of the screws, twist clockwise, and tighten the screws.

What are the dimensions of attachments that I should be seeking for these lenses? I suspect that the Schneider will slip through a smooth hole and be held by the retaining ring, whereas the El Nikkor will screw into a threaded hole on the attachment piece, but I could be wrong about this.


The Schneider came with a rear lens cap and a retaining ring no front cap. The El Nikkor came with a front lens cap but not a rear lens cap. If anyone can suggest where to find these, I would appreciate it.

The El Nikkor came with what was described as a retaining ring but I suspect is really attachment hardware to some other enlarger. It has an outer diameter of approximately 72 millimeters, and five holes that I assume are for attachment screws.

I have read that the 80 mm El Nikkor will work with 67 medium format. Is this correct? And if so wnhat do I need to attach it to the Prolab?

You are correct in the assessment that an adapter plate can be harder to find or more expensive than a lens. In fact, if one has a plate, it is sometimes easier to pick up a lens to match any adapter one has.
Best to check out the on-line PDF for the D5 because there are many, many ways to mount lenses, either individually or on the turret. The 80 will likely work for 6x7 at moderate magnification. I don't shoot 6x7 but know the 80mm it won't cover 6x9 for me (blurry at the corners).

Also check out the KHB Omega enlarger guide. It has the six-digit part numbers of all the lens mounts. Knowing the six-digit number makes serching the internet for a specific part easier.

@ic-racer

Thank you.

I'll look up the KHB guide.

I'm printing 11 x 14 or 16 x 20 at this point, and might want to go to 20 x 24. So i guess that the 80 mm El Nikkor won't do.

There is also A Schenider Kreuzback 100 (maybe 105) in the darkroom, as well as an El Nikkor 135, which hopefully have attachment hardware. Will these work for that purpose?

I've always understood that you wanted an enlargement lens as close is possible to to normal lens size of the format you're working with.

A focal length of 100-105 mm is probably better for 6x7, but an 80 can work, as ic-racer said.

Often the hole in the enlarger's lensboard is threaded and the lens simply screws on. In other cases, it's a smooth hole and you need a retaining ring of some sort that threads onto the lens and essentially clamps the lensboard between the lens body and the retaining ring. In some other cases the ring has screw holes like the one you have and can either be fastened to the lensboard with screws in those holes or just used as you would a retaining ring.

The 135 would work for your 6x7 negs but the magnification will be a little low, it's more commonly used for 4x5.

The common mounting diameter is 39 mm but lots of lenses are different, for example, the 135 El Nikkor's body is 50mm and (when new) Nikon supplied an adaptor that is 39mm. The lens can be used either way, but I like using it with the adaptor better on my enlarger.

Yes, generally you use the format's "normal" focal length but there are a lot of reasons to vary from that, for example, if you like small prints, a longer than normal lens will work better. On the other hand, if you are trying to print large you may get to the limit of the enlarger's column and find you need need more magnification (which you get with a shorter focal length).

Here is the KHB reference for Omega D5/D6 series lens mounting plates: http://www.khbphotografix.com/omega/LensMountD5.htm

I'm assuming yours is either a D5 or a D6 - Prolab refers only to the head.

If it is another model, you will need different plates.

The reference to the "plate that slides into the bottom of the head with an oval shaped drop" is probably a reference to the lens mounting plate itself. You may need to use a different one for one or both of your lenses.

As you will note from the linked table, both of your lenses came in at least two different versions (different mounting threads) so you will need to determine which ones you have and therefore which mounting plates you need.

I have my lenses on two different three lens turrets (I have too many!). The turrets just slide in.

A 90mm lens is ideal for 6x7. Some 80mm lenses work. Many prefer to use 105mm. 150mm will give you very small enlargements.

Back caps are often a challenge. I keep my lenses on mounting plates, in small tupperware containers.