OMEGA Pro-Lab B66 Photo Enlarger what enlarging lens needed

camerabrain · Mar 31, 2022

I want to make 5x7 prints. What size/type of lens would I use on the enlarger?

Pieter12 · Mar 31, 2022

It really is the negative size that would determine the lens,

albada · Mar 31, 2022

Pieter12 said:
It really is the negative size that would determine the lens,

Yes.
I think the general rule is to use a 50mm lens for 35mm negatives, and an 80mm lens for 6x6.
However, when making small prints (4x5 or 5x7) from 35mm, I like to use an 80mm lens to keep the head higher.

Mark Overton

Pieter12 · Mar 31, 2022

I usually use a longer focal length than "normal" unless I am making small prints. I like to think that by doing that I am more in the sweet spot of the lens, not getting fall-off or distortion from the edges. Might just be fooling myself, but my prints are sharp.

Paul Howell · Mar 31, 2022

I think the B66 will take up to 6X6 negatives, so the longest lens it will take is likely a 80mm which will work for 35mm 5X7. 80smm is the longest lens the B66 was designed for when printing from 6X6 you will need to do the best you can. Like others I like to use a longer lens when printing 5X7 as I can keep the enlarger head further up the column which makes it easier to use a grain focuser aid.

Sirius Glass · Mar 31, 2022

Generally 50mm for 35mm film, 70mm to 80mm for 120 film and 135mm to 150mm for 4"x5" but there is no rule just a range of what people use and plenty of debates.

Rick A · Mar 31, 2022

Sirius Glass said:
Generally 50mm for 35mm film, 70mm to 80mm for 120 film and 135mm to 150mm for 4"x5" but there is no rule just a range of what people use and plenty of debates.

There are several formats available using 120 film, 6x4.5, 6x6, 6x7, 6x8, 6x9, 6x12, 6x17. You can get by with an 80mm lens for the first two, but as your negative size increases so should your focal length, 90mm for the next two, and105mm for 6x9. With a B-66, you would only need a 50mm and 80mm lenses to cover what the enlarger is capable of.

randyB · Mar 31, 2022

If I remember correctly, the B-66 uses an auxiliary condenser when using the 50mm lens for 35mm negs. It concentrates the light to make a brighter image. It fits on top of the double condensers. The original instructions or if you can find a copy online will have a layout of how they fit. THE B-66 is a nice enlarger for 35mm/6x4.5/6x6 negs, just use a top quality enlarging lens.

ic-racer · Apr 1, 2022

Negative size??

Ian C · Apr 1, 2022

Due to the design of the Omega B66 and the formed lens mounts for certain other Omega enlargers, such as the D5/D6, the 39 mm x 26 thread-per-inch retaining rings have to be selected to fit the enlarger or lens mount.

The 39 mm Beseler retaining ring has too large of an outside diameter to fit into the hole in the B66 lens stage. It requires the Rodenstock-pattern ring to clear the hole. Some of the D5/D6 formed mounts have the same requirement.

The following are the ring O.D. x thickness

Beseler M39 ring: 1.872” x .080” = 47.55mm x 2.03 mm

Rodenstock M39 ring: 1.789” x .119” = 45.44 mm x 3.02 mm

Omega B66 opening: 1.860” = 47.24 mm

OMEGA Pro-Lab B66 Photo Enlarger what enlarging lens needed

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