Replacing a MF folder lens

I may have to replace a 105mm triplet on a MF 6x9 folder. I want to put a four element coated lens in its place.

Has anyone successfully done this? I know I may need to shim it out with spacers.

Has anyone used a 100mm Kokak Anastar lens for this? I am thinking that the 5mm distance will be too much to compensate for and it will not be doable. It would probably require a major rework of the front standard mechanism.

Whether the 5mm difference will be too much will depend on the actual focal length and flange focal length. The 105mm lens may well be shorter than the 100mm lens, and both can still be within tolerances.

Try it - if you get infinity focus, it works. If you don't, it doesn't...

Ole said:

Whether the 5mm difference will be too much will depend on the actual focal length and flange focal length. The 105mm lens may well be shorter than the 100mm lens, and both can still be within tolerances.

Try it - if you get infinity focus, it works. If you don't, it doesn't...

Click to expand...

Yep, you are entirely correct, thank you. You are always a great source of information Ole.

But before I spend the money I would like to know if someone else has successfully done it with an Anastar. Might save me the trouble.

I should add: a couple of months ago I had the opportunity to buy a 105mm Color Skopar and I hesitated. When I made up my mind, it was gone.

Actually, I have done a few folder camera lens conversions. Going from one 105mm to another is generally close to being a straight change, though it helps to have some shims. You will also need to rig a ground glass, or some type of focus screen to the open back of the camera. This is also something that only work with front cell focusing lenses, otherwise you would create a fixed focus camera.

Going from a 105mm to a 100mm would be tougher, since the latter would need to be closer to the film plane. Unless you want to try major surgery on the camera front standard, I don't recommend it.

When I reset focus using the ground glass, I tested first at 2m and then at 4m distances. What I found was that when you get those correct, infinity focus ends up in the proper orientation. When I first tried it the other way, with infinity set first, then the closer distances were always off.

I should mention all the conversions I did were AGFA or ANSCO. Several of the Balda lens/shutter units are similar. I have also done a few lens elements swapped into different shutters. The only real tough one was a Synchro Compur that required me to create a different shutter release, because the trigger mechanism on the camera was lined up differently.

Ciao!

Gordon Moat
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