Canon 50mm f1.4 ltm disassembly

[SteveM]

I've found and followed some instructions for cleaning the Canon 50mm f1.4 ltm lens, and initial disassembly is quite easy. However, the main part I want to clean and re-lube is the focus helical.

Once the rear retaining ring is removed, the focus assembly slides off the back, leaving the lens group intact. Next, I removed the small screws holding the rear portion from the focus barrel. The remaining part contains the focus helical - see the attached photos. The first photo shows the threads of the helical protruding at their maximum. All screws have been removed, including the two little screws visible from the back of the lens.

From this point, and I can't see how to undo the inner from outer helical to clean and re-lube. Can anyone advise on how to do this?

Thanks,

Steve

 

[johnamazement]

I cleaned a f1.8 version a little while ago and if it's the same (and I remember correctly), look down from the front and you should see a two blocks 180° apart from one another. One of them has a sort of tongue which points down towards the mount. This acts as a stop to the helical's movement. When removed (you should see a screw on top) the helical can be screwed all the way out giving access to the full length of the thread.

 

[SteveM]

John, thanks for the info. The 1.8 helical seems to be held in place a little differently than the 1.4. However, using the theory that if you stare at something long enough you begin to see things you didn't notice, I've now got it apart. No screws hold the helical together, it is another retaining ring. I've attached a few photos to show this.

The first photo shows the rear mount (you can see the infinity lock stop), the helical itself, and the retaining ring. The ring is difficult to see at first (at least for me) but can be removed with narrow width lens spanner. The focus helical then can be unscrewed to relube.

The second photo shows the focus ring at the back, the focus helical to the right and the helical retainer in front. In the retainer, you can just see a small tab at the top. This is held in place by two small screws that can be seen on the rear mount of the lens, and they don't need to be removed. This tab fits in the groove that can be seen in the focus helical to stop it rotating as the lens is focussed.

I've been playing around with some vacuum grease and can't get the right weight on the focus damping, but I've read that white lithium grease works well. I'll be giving that a try next.

A final note, the lens group does not need to be touched if you only need to relube the focus helical. Once the back end of the lens is off, you also have access to the aperture indent bearing, but so far I haven't dug in deeper to relube the aperture ring. It looks like the front of the lens needs to come off. Maybe later. This is one solidly made lens.

Steve

 

[pbo]

Hey Steve,

I'm trying to take off that hard to see retaining ring to relube the lens, but I've been trying for about 20 minutes now, and it doesn't come off! Is it screwed in very tight? I'm rotating counter-clockwise.

Bo

 

[SteveM]

Hey Steve,

I'm trying to take off that hard to see retaining ring to relube the lens, but I've been trying for about 20 minutes now, and it doesn't come off! Is it screwed in very tight? I'm rotating counter-clockwise.

Bo

It was relatively tight on mine, and it was not easy to get the wrench tips into the slots of the retaining ring. I pushed the tips in at the same time as rotating, holding ring in one hand, wrench in the other. Once it had moved a tiny bit, it rotated very easily. Counter-clockwise rotation is correct.

Steve

 

[SteveM]

Oh, one more thing that might help. The helical on my lens were pretty tight so before I took it apart I dabbed small amounts of naptha into the threads. With a bit of working around this loosened the threads a lot. Try dabbing a bit of naptha into the space between the outer chrome rear mount of the lens and the brass retaining ring - that's where the threads engage.

Steve

 

[pbo]

Oh, one more thing that might help. The helical on my lens were pretty tight so before I took it apart I dabbed small amounts of naptha into the threads. With a bit of working around this loosened the threads a lot. Try dabbing a bit of naptha into the space between the outer chrome rear mount of the lens and the brass retaining ring - that's where the threads engage.

Steve

Thanks, I was using GooGone and it's still not turning. I'll try some more I guess. I'm thinking about putting the whole focusing part into a ziplock and putting it into a fridge or under running hot water, see if the different metal parts (chrome and brass) expand/shrink at a different rate.

 

[High Life Kojo]

Canon LTM 50mm 1.4 Pro Repairs

Canon LTM 50mm 1.4 Pro Repairs

I bought a Canon LTM 50MM 1.4 lens which is in excellent shape but is very stiff at the f stop ring. I does not move easily and I wonder is a pro repairer could be recommended to take a look at it.

Thanks,

High Life Kojo

 

[richowirawan]

Hi Steve,

Do you know where to look at the disassembly manual for this lens? I tried to look for it online but couldn't find any trace.

 

[bastian786]

Disassembly of Focus Helical

Disassembly of Focus Helical

Hello,

I got a copy of this wonderful lens but am stuck during disassembly. I files a spanner wrench to fit the slits in the locking ring and soaked it in WD-40 to convince it to move- no success.

Just to be sure: we are talking about the slits which are circled in red on the picture (and the counter part on the opposite site)? Any ideas what I could try?

Thank you!

Bastian

 

[Chriscrawfordphoto]

I bought a Canon LTM 50MM 1.4 lens which is in excellent shape but is very stiff at the f stop ring. I does not move easily and I wonder is a pro repairer could be recommended to take a look at it.

Thanks,

High Life Kojo

If you're in the USA, Don Goldberg or Youxin Ye

 

[maigo]

I sent my Canon 50/1.4 to YY for cleaning and lube a few years ago.
Top notch job, good price, great communications and quick turnaround.


Sent from my iPhone using Tapatalk

 

[skahde]

As an update to this old thread, I also tried to relube the helical on a recently bought Canon 1.4/50 mm LTM Type II and also failed to loosen the retaining ring.



After trying for some time I considered it may not really be necessary to get the helicoid out and stopped before I could damage anything. I had already soaked the lens in lighter-fluid for about an hour, worked the helicoid and resoaked it for several times to get the old grime out of the helicoid and now just let it dry.
When focussed to infinity there is enough of the helicoid-threads accessible to apply fresh lubricant (I used Klüber Catenera KSB 8, a dampening-grease of medium viscosity, which turned out to be just right. You might even go higher in viscosity if you like). I generously brushed grease in the threads and worked it into the helicoid by focussing back and forth, reapplied grease several times and didn't forget to also work a little into the slit under the retaining ring.

This worked just fine and the lens focusses like new. So if you have trouble removing that retaining ring, it may be a problem that can easily be ignored.

 

[peterm1]

I've been playing around with some vacuum grease and can't get the right weight on the focus damping, but I've read that white lithium grease works well. I'll be giving that a try next.

I have often used white lithium grease. As you say the correct viscosity is needed and even with this grease I think there are different variants - with different viscosities. For convenience (of storage as much as anything) the one I use most is in spray form. Needless to say, I do not actually spray it on the helicoids but rather into a saucer or something of the sort and from there apply it thinly with a cotton bud so as not to over-do it and run the risk of having the grease later migrate to the aperture mechanism of inner lens elements. The one I have seems quite thin - consistent with it being in spray form but I think that for most lenses that are not unduly worn this is all that is required. Having said that, local climate can also play a part in choosing the lubricant (I am an Aussie and so do not have cold "continental' type winters.

 

[skahde]

As said above I used Klüber Catenera KSB8 with good success, data for this product is available online:

https://www.qualitybearingsonline.com/content/Lubricants/MSDS%20and%20TDS%20PDFs/Kluber/CATENERA_KSB__6_8_12_EN_en.pdf

Lower/upper-limit viscosity is 6000/10000 mPas.