Mintola M 90mm f4 - Dissassembly/cleaning

[Ibanez]

Advertisement (gone after registration)

Hello all. 

I recently purchased the above lens to be used with my newly purchased M5 which is currently being CLA'd. I am aware of the potential focusing issues of using a lens made for the CL/CLE lens  system on a fully fledged M camera. I am not too fussed by this as I bought the lens on a whim as it had haze, not fungus (which I am certain of!)

I have some experience of lens repair, but this is the first time I have tried to clean a M mount lens. I cannot find any repair manuals on the internet (apart from one obscure post here from many years ago) on how to access the rear/front element to allow a thorough clean to be done. I have attempted to remove the rear bayonet to see if this would allow access to the rear lens element, but I could not see a logical way to disassemble the lens. 

Could anyone please provide some steps/tips on how to disassemble the lens to access the lens elements? I am reluctant to send the lens away for a full CLA as it is not economically viable and my other lens (nikkor 5cm f2 ltm) is currently being CLA'd, which I use as my main lens for the M5. 

Kind regards

Ibanez. 

 

Edited May 22, 2022 by Ibanez

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[TomB_tx]

Sorry, no info on disassembly, but I have both the Leitz CL 40 & 90 lenses and have used them without focus problems on various film & digital M bodies. In theory the sloped-cam design can have issues, but I suspect that is rare depending on the am adjustment in the M body.

Erwin Puts noted that Leitz actually made the Minolta CL version of the 90 for Minolta. I was amazed at the image quality of the lens - it's a great bargain.

Minolta made their own lenses for the CLE, with some optical and mechanical design differences. I've heard that the CLE versions did not use the sloping focus-cam design of the CL lenses, and so should not have focus problems on any M body.

[Ibanez]

25 minutes ago, TomB_tx said:

Sorry, no info on disassembly, but I have both the Leitz CL 40 & 90 lenses and have used them without focus problems on various film & digital M bodies. In theory the sloped-cam design can have issues, but I suspect that is rare depending on the am adjustment in the M body.

Erwin Puts noted that Leitz actually made the Minolta CL version of the 90 for Minolta. I was amazed at the image quality of the lens - it's a great bargain.

Minolta made their own lenses for the CLE, with some optical and mechanical design differences. I've heard that the CLE versions did not use the sloping focus-cam design of the CL lenses, and so should not have focus problems on any M body.

Thank you for your reply, very informative. My copy of the lens is one of the earlier,  "made in Germany" and "made by Letiz ones. I was thinking of selling it and obtaining a copy in better condition but, you have changed my mind!

[RalfJ]

Hello - I bought one of these knowing full well it had fungus in rear element group. It took a while before figured it out. 

I also searched through the web to no avail, so I figured I can help here. 

Disclaimer though: I do not have any special tools except for a spanner lens wrench, so proceed at your own risk. Take your time and have patience to avoid any damage to optics.

1. Rear Dust/Dirt retaining cover unscrews easily with spanner wrench, please take care not apply too much pressure as the cover is very light ( I think plastic) and it can easily be cross-threaded.
2. Once that is out of the way, the biggest challenge is removing the front lens group retaining ring. This requires a special tool. In its absence, I made two tiny notches with an angled file, deep enough for my spanner wrench to go into slots (including photos as well). Unscrew this counterclockwise holding front group with your supporting hand. Once this is unscrewed, the lens groups will separate. Be mindful of the brass spacer ring inside so it doesn't get lost.
3. Once the groups are separated, the rear element housing just unscrews easily counterclockwise. You now have access to clean inside of the rear element.
4. When assembling back, ensure the everything is aligned properly, ie aperture marker with fixed marker, making sure the front lens group is fully seated in the focusing helicoid. ( I messed this up on my first try  , no harm done as I corrected it on second try)
5. Carefully thread the rear cover in and voila, you're good to go.

 

One note to add, I am not saying this is the right way, but this way worked fine for me. 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!