Strange rangefinder movement 90:2.8 TE “fat”

[grahamc]

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Hello

i have an issue with one of my lenses and I wonder if anyone’s seen this before.

When moving the focus ring towards MFD, the moving part of the image in the rangefinder patch “bounces” when the lens focus ring reaches the hard stop. 
 

So the moving image in the rangefinder patch will travel all the way to the stop  (from left to right) but then when the lens ring reaches hard stop the image in the rangefinder jitters back left about 1mm (then stops). 
 

consequently the resulting image of of course also not in focus (but front focusing). 
 

Other lenses are fine with the rangefinder. has anyone seen this before or know what the issue could be pls ? Obviously off for a service also 

thanks 

Graham 

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[earleygallery]

Does the focus ring turn beyond the MFD? I expect it does and the rangefinder cam is going beyond the useable range.

[grahamc]

18 minutes ago, earleygallery said:

Does the focus ring turn beyond the MFD? I expect it does and the rangefinder cam is going beyond the useable range.

Thanks. It does yes.   That’s quite normal with my lenses though, most of them seem to travel past the MFD marker 

Is it a simple adjustment do you think ? 

[wda]

I no longer have this lens, but my recollection is that focusing was precise, without any over-run or infinity error. 

[UliWer]

The minimal focus distance of my "fat" Elmarit is also slightly below 1m; I think that's normal as grahamc already said:

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Though I don't recognize any "bouncing" of the rangefinder patch as described in the first posting. That's true for the M10 as well as for the M3, the latter sometimes shows this behaviour when a lens is focussed closer than 1m which the M3-rangefinder does not support. 

Since it is the rangefinder patch which shows the odd behaviour, there might be some mechanical issue in the rangefinder. So for the time being I'd try to "loosen" the rangefinder's mechanics with another lens which goes  closer than 1m by focussing it in the close range with repeated motions. 

[earleygallery]

I think the issue is if it's focussing closer than 0.7m then it's beyond the limits of the rangefinder. I guess the solution is ideally not to try to focus at less than 1m.

[grahamc]

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Thanks yes it’s definitely a fault as the “bounce” is hard to miss. I’ll do some tests to see if focus is on at around 1m.  But I often use the hard stop in practical use so it will need fixing either way.   The lens also is very stiff to Mount to my m10 (much less so on my M6). I’m unsure if that’s related or not though because the ‘bouncing’ of the rangefinder patch image occurs on both bodies 

Edited November 27, 2022 by grahamc

[TomB_tx]

I've owned a FAT TE since 1968 and never noticed any such issue with it. However, the Leitz lenses of this period were focus calibrated by precision grinding of each focus cam (the brass surface just inside the lens mount) to correct for individual focal length. If you look at the cam you'll see where this grinding took place over the focusing range. It might be possible that the ground area on your lens ends just at the mfd stop, so the camera follower might be at the transition of the ground area.

I bought mine as the first lns with my new M4 - so I've always used it on cameras that supported .7m mfd.

[lct]

3 hours ago, grahamc said:

Thanks yes it’s definitely a fault as the “bounce” is hard to miss. I’ll do some tests to see if focus is on at around 1m.  But I often use the hard stop in practical use so it will need fixing either way.   The lens also is very stiff to Mount to my m10 (much less so on my M6). I’m unsure if that’s related or not though because the ‘bouncing’ of the rangefinder patch image occurs on both bodies 

When the curtain of your M6 (M6J below) is open, do you see the roller cam bouncing while focusing nearby MFD?

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[grahamc]

Thanks everyone.

@lct the issue with the T-E Fat happens on both M10 and M6 (J also 👍), but with my other lenses I can't replicate it on either body.  So should I still check as your instruction ? if so how do I keep the shutter curtain up (bulb model ? )

I've sent the lens off this morning for diagnosis as I am impatient especially when things aren't working 

Cheers ! 

[lct]

39 minutes ago, grahamc said:

Thanks everyone.

@lct the issue with the T-E Fat happens on both M10 and M6 (J also 👍), but with my other lenses I can't replicate it on either body.  So should I still check as your instruction ? if so how do I keep the shutter curtain up (bulb model ? )

I've sent the lens off this morning for diagnosis as I am impatient especially when things aren't working 

Cheers ! 

I don't remember how the focus cam is on the fat T-E. It is not a sloped one i suspect but you would need the lens to check it anyway so wait and see what the diagnosis will be.

[1joel1]

The brass focusing surface drops below the cutout on the mount. That's why it "bounces" and this is not a problem. Mine goes way beyond 1 meter as well but I don't use it to focus that close.