[LowVoltage]

I would like to disassemble this old Beseler 75mm 3.5 enlarger lens. There is absolutely no obvious way to take the thing apart for servicing. Does anybody have any ideas on how to do this?


No hint of screws or other apparatus that holds the thing together. A friend of mind who works at a place doing lens and camera repairs suggested the beauty ring (the front surface with the name and serial number on it) might hide screws in a fashion similar to Canon lenses. However, there is no obvious way to remove that surface. The rear element has a thick metal ring around it, and it appears the ring might be threaded onto the assembly. However, the ring does not budge for any amount of force applied to it. I've tried using a rubber band to improve gripping power with no success. I, nor my friend, have any kind of tool that would fit in the gap between the ring and the outer part of the lens barrel. I suspect the ring may be held in place with some kind of glue like Loctite. There is a seam where the aperture ring meets the other half of the lens body, however exerting force here would very likely break the aperture mechanism and have nothing to with opening the lens. I have searched every resource I can think of and can't find any reference to servicing this thing.

I'm hoping to sell the lens along with its matching enlarger. I expect somebody will pick up the enlarger more readily if they don't have to worry about picking up a lens to go with it. The problem is the aperture blades are oily and some of the lubricant has atomized onto the inner surfaces of the elements. I'm willing to at least try cleaning the thing; this kind of enlarger lens has a very simple optical formula. I think it's only three elements.

Any suggestions would be appreciated!

[Not a Number]

The trim ring with the serial number probably unscrews and there are either retaining rings or screws underneath. Something like a rubber end for a chair leg will probably serve as a good tool to unscrew the trim ring. Retaining rings would use a spanner but you can improvise with a set of calipers, scissors or the like. I don't recommend using a screwdriver - you can do it but one blade tends to slip.

[LowVoltage]

As a matter of fact, upon reading the comment about unscrewing the very front, it appears there may be two contact points for a spanner of some kind. They are basically two miniscule metal dots. The problem is they are practically touching the element glass. Not exactly safe. Nevertheless, I will give some of this a try. The front ring does have some a seem where it meets an outer portion of plastic, so perhaps that is the starting point to this adventure. Thanks!

[Not a Number]

You can probably use a drawing compass with two metal points. A rubber tip would probably be safer.

[LowVoltage]

You can probably use a drawing compass with two metal points. A rubber tip would probably be safer.

Good call, I hadn't thought about that. It still makes me nervous, though. The metal dots I mentioned lay across from each other at the diameter of the element, so they seem to be strategically placed for a reason. But like I mentioned, they're so darn close to the glass! I guess I'll see what happens.

[LowVoltage]

The trim ring with the serial number probably unscrews and there are either retaining rings or screws underneath. Something like a rubber end for a chair leg will probably serve as a good tool to unscrew the trim ring.

I ended up using the tip of a cane to get purchase on the trim ring. Apply a little pressure and the thing unscrewed easily. Unfortunately it only revealed a deeper recess with the next element but no obvious way to take apart the rest of the lens! No screws or slots... There are the kind of ridges (baffling, flocking, whatever you want to call it) similar to what one might find on the inside of a lens hood. Likely meant to reduce light bouncing around on the inside surface.

So now I'm back to square-one. I can't help but think the rear element construction might yield something, if only I could get the retaining ring off. It seems glued in place, though.

[Not a Number]

Perhaps if you post some pictures the mechanically minded here might see something you are missing.