Canon 28mm f/2.8 LTM - how to take off front element?

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p-c

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Hello,

I'm cleaning the aperture blades of a Canon 28/2.8 LTM lens and I'm done with the back of the blades and also relubricating the focusing ring. However, the usual front retaining ring to take off the front element is hard to see on this lens. No small screw to unscrew on the side of the outer ring and no small dumps for the spanner anywhere in front. I'm not sure if it should just be unscrewed, - if so the recessed black inner element or the outer chrome ring...?

Have any of you disassembled the front element of this lens before and how did you manage?

Thanks in advance!
 
I don't recall specifically from this lens, but typically if there are no detents for a spanner, you'll need to use a rubber plug or stopper to twist the front ring off by friction. Be sure to find one that is shaped in such a way that it doesn't mar the front element.
 
Thank you for replying, 02Pilot. I just ordered a set of rubber tools and will give it a try when they arrive. Would be nice to know for certain though, so if anyone has worked on this lens and knows, please share :).
 
That's because it was never going to work. You cannot remove the Canon LTM 28mm f2.8 front element from the front of the lens. First you need to separate the optical cell from the barrel of the lens. You do that by loosening and removing the retaining ring on the back of the lens and pushing the optical cell backwards and out of the barrel. The lens is 6 elements in 4 groups - 3 elements in 2 groups screwed into the front of the aperture mechanism housing and 3 elements in 2 groups screwed into the back of the aperture mechanism housing. First you unscrew the 3 elements in 2 groups screwed into the front of the aperture mechanism housing as one piece, then you can separate these two groups by unscrewing them. That will give you access to the underside of the front optical group.
 
Thanks for posting this jonmanjiro. I've had mine completely apart, but for the life of me I can't remember the whole procedure.

Both the Canon 28mm f2.8 LTM and the Canon 35mm f1.8 LTM come completely apart and can be thoroughly cleaned. They're a bit confusing, but it's nice to be able to take a 60 year old lens and bring it back to original condition.

Best,
-Tim
 
thanks, jon!!! i might get mine recoated by arax after all (previous owner or seller polished them off).
 
Sorry for reviving an old thread.

I'm trying to take apart my lens to clean the front group.

View #1
49163666727_2a1d84063b_c.jpg


View #2 from another angle
49163666742_624532da8b_c.jpg


Following Jon's instructions above "loosening and removing the retaining ring", may i ask which screws to loosen and remove (circled green or circled red)?

Thanks in advance!
 
Managed to take it apart for cleaning. All screws circled above are to be removed, and the optical call can be pushed forward (into the plane with reference to the above pictures).

However, I did observe that the front group could probably be removed from the front by use of a sized rubber tool, fictionally turning the slopped portion interior of the name ring. The name ring does not move, and stays fixed to the barrel.

Any suggestion/tips on repainting the flaked black paint on the lens elements periphery ?
 
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