Canon 50mm f/1.8 II LTM optical module play

[borge]

Hello

Regarding this lens: http://global.canon/en/c-museum/product/s47.html

I recently found what looks to be a mint (cosmetically) example of this lens, including a Toshiba 40mm SL-C UV filter from the same time period. Everything is smooth on it, no oil on the blades, or anything like that. I can see that the retaining ring in the rear has some marks on it around the etches, so it's clear that the lens has been serviced at some point.

While the lens looks almost like new, it has some sideways/rotational play between the rearmost ring (where the mount is) and the optical module. Metal clicks are audible, and it doesn't feel good when I twist the focusing barrel rapidly. At the same time it's not to the magnitude that the optic module feels like it's gonna fall out.

This is a picture of the lens, and the lens play is between these two parts:



I wonder if anyone know if this is normal on these lens? And if not, is it possible to fix it some how? And is it a DIY?
I'd really like to be able to keep it, as it focuses spot on, except it has some focus shift from f4 (checked on digital) at 5ft, which I guess is normal and wouldn't be visible with film. But the some what loose optical module worries me.

 

[peterm1]

My 50mm f1.8 is in storage but I have to hand my 50mm f1.4 of the same era and it does reveal some rocking movement (quite small but discernable) in that area. Another issue often experienced when rotating the barrel to focus is backlash - some free movement (ie slop) in the rotation that does not actually translate into focusing movement for a few degrees of movement. You may be experiencing this too. If I have a moment tomorrow I will dig out the other lens and check. I have also seen some earlier chrome variants of the lens with similar movement between parts of the lens barrel. I happen to have one of these too and will check it. I suspect it's not unusual. If the lens does not feel good when focusing quickly this sounds more like the need for new grease in the helicals which can also remedy backlash.

 

[kuuan]

I don't believe that this play is normal. at least the copy that I am having with me right now doesn't have it
I just took apart that lens, just a bit, to see if there is an easy fix.

the 3 parts after removing the rear retaining ring, the ring itself, the optical part and the helicoid part:

Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr
I noticed that your photo the inner helicoid, here indicated by the red arrows, looks as if was not threaded but solid copper?
how is that possible? could this be a non original part and cause of the problem?

in any case it become obvious that the part of your lens that has play is not the optical block but the "helicoid block"
inside are many retaining screw


Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr

but opening them does not lead to a play at the same place as you indicate.
the play seems to be between the inner helicoid, indicated red, and the outer helicoid indicated green. see the distances between the two blue arrows when set to infinity


Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr

and when set to the lens' close focus distance:

Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr

here after taking off the first 4 screws and the focus ring these hold. when rotating the helicoid the movements is between the two metal rings indicated by the red arrows:

Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr

and at close focus distance:

Canon LTM f1.8/50mm by kuuan's lens tests, on Flickr

If the play is not due to the metal of the two helicoids having been 'reduced' due to heavy use than possibly one can tighten the two helicoids to each other by tightening the ring that has 4 notches which I indicated by blue arrows. However I had no success trying to move that ring, well, my lens is well working and I did not try all that hard.
Still I hope that this may help you and encourage you to open up your lens and see to it,
best luck

 

[borge]

I don't believe that this play is normal. at least the copy that I am having with me right now doesn't have it
I just took apart that lens, just a bit, to see if there is an easy fix.

Thanks so much for your very informative post! That really helps!

The brass part that is sticking out on the rear of my lens is indeed solid, except it has a straight groove in it - see the picture.

And yes you are right. It is the brass ring and the outer "barrel" where the distance scale is that has side-ways play. There's no up/down or in/out wobble, only side-ways play.

I have the Canon 35/2.8 LTM, which has the same type of brass ring that's on your 50/1.8 LTM, and there is no play in my 35/2.8 - or, if I really want to, I can detect some very very minor movement, but nothing like I experience with this 50/1.8.



I've read some where else earlier that Canon changed the manufacturing method a lot on these lenses, even on the same series (Series 1, 2 and 3) and that there are differences in manufacturing methods within the same series of lenses. Can that be the reason? Or is this lens clearly not original? In that case I need to open a case with eBay and get my money back.

I don't have the tool to be able to open the retaining ring, otherwise I would have done so immediately.

I googled images of the Canon 50/1.8 LTM though, and found several images of other identical lenses that has the same type of focusing helicoid/brass part, which is smooth just like mine, and with the same straight groove. Two examples here are the 50/1.8 LTM, and one example is the Canon 50/1.4 LTM. The brass part looks exactly the same as on my copy.

Small images, but you can see it: http://www.terapeak.com/worth/canon-50mm-f1-8-ltm-m39-lens-50-1-8-black-ring-862/141899084810/

http://picclick.ca/%E3%90Vintage-EX...eica-Screw-LTM-302059067186.html#&gid=1&pid=2

327x later serial number one on eBay that has the same: http://www.ebay.com/itm/Near-Mint-C...723110?hash=item2a744b5f66:g:~5AAAOSwcUBYEd0D

Scroll down to see images: http://forum.mflenses.com/confused-about-a-canon-50mm-f-1-4-ltm-t72018.html

Another 50/1.4 LTM, just to illustrate that is exactly how mine looks: http://picclick.ca/Excellent-Canon-50mm-F14-Leica-Screw-Mount-LTM-162224846462.html#&gid=1&pid=2

Also, it seems to me we must have two different versions of the lens? Your example only shows the distance scale in ft/feet, while mine only shows the distance scale in M/meters. Mine is serial number 273824.