Canon 50mm 1.2 M39 on Leica M

[former member]

Raid, Thankyou.

I'm on my third Canon 50/1.2, the prior two had some damage to the surface behind the aperture. Common on these lenses. The one I have now, an early one made in 1957. Picked up last year.

This is with the prior one, some coating damage- but very usable.
Wide-Open on the Canon P.



Sold this one when I bought the 50/1.1 Nokton- 10 years ago.

 

[tardegard]

The optical barrel is held in the focus mount using a retaining ring, which comes out from the rear. The lens uses a shim- a metal ring. If your lens is front focusing: the shim is too thick. The other possibility is that the optics are out of place in the lens, or the helical in the focus mount is not assembled correctly.

Take some pictures of an object at 1meter focus and at infinity. Knowing how far off the focus is from the RF will indicate what corrective action to take.

https://johanniels.com/canon-rf-50mm-1-2-cleaning-leica/

Hi Brian, at around 1 meter the lens front focuses by around 14, 15 cm.
It doesn't get to infinity at all but gets to 15/20 meters tops.

 

[raid]

My 50/1.2 was giving me strange looking images in which the focus area was diagonal across the frame. I sent the lens to DAG to check it out, after three camera repairmen failed to identify the issue. Don discovered that one of the lens elements had shifted out of place, and this caused the lens to have a weird looking focus coverage in each image. He moved that lens element back into place, and this lens is doing very well now.

 

[Erik van Straten]

I have the 50mm f1.1 Nokton, but now I see those pictures by Raid and Brian, I would love to have the Canon LTM 50mm f1.2 too. Very nice painterly; the Nokton is much more strict in its drawing. I feel I need both of them.


Erik.

 

[raid]

The 50/1.2 Canon ltm lets you use window light for portraits and without the harsh sharpness of the fast modern lenses. I used the M6 with Fuji Reala 100.

 

[former member]

Hi Brian, at around 1 meter the lens front focuses by around 14, 15 cm.
It doesn't get to infinity at all but gets to 15/20 meters tops.

That is not so far off that it could be caused by the Helical being misassembled. It is a lot for the shim to be off. If you have a spanner, or other tool to remove the rear retaining ring- would be worth looking to see if more than one shim has been used.

SO- 1m focus should have a back-focus of 54.4mm. Your lens actually focuses at 0.85m- 15cm too close, which would requires 54.9mm back-focus.
I would start by reducing the shim by 0.5mm.

And- completely agree about the quality of the images from this lens.
One GOTCHA: the front element protrudes, Canon made special filters for this lens with the glass all the way to the front of the filter. It used a clamp-on hood. If you cannot get the original filters- use a 55-58 step up ring, or tale the glass out of a 55mm filter and use as a spacer.

Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr

Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr

I used the clamp from an Olympus rubber hood for the 35~70 zoom, then epoxied a vented 58mm hood into it. About $10, much less expensive that the originals.

 

[tardegard]

That is not so far off that it could be caused by the Helical being misassembled. It is a lot for the shim to be off. If you have a spanner, or other tool to remove the rear retaining ring- would be worth looking to see if more than one shim has been used.

SO- 1m focus should have a back-focus of 54.4mm. Your lens actually focuses at 0.85m- 15cm too close, which would requires 54.9mm back-focus.
I would start by reducing the shim by 0.5mm.

And- completely agree about the quality of the images from this lens.
One GOTCHA: the front element protrudes, Canon made special filters for this lens with the glass all the way to the front of the filter. It used a clamp-on hood. If you cannot get the original filters- use a 55-58 step up ring, or tale the glass out of a 55mm filter and use as a spacer.

Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr
Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr

I used the clamp from an Olympus rubber hood for the 35~70 zoom, then epoxied a vented 58mm hood into it. About $10, much less expensive that the originals.

ok Brian I'll try this, I am a little noob at modding lenses though, could you be a little more specific and tell what part of the lens a need to unscrew?

 

[tardegard]

That is not so far off that it could be caused by the Helical being misassembled. It is a lot for the shim to be off. If you have a spanner, or other tool to remove the rear retaining ring- would be worth looking to see if more than one shim has been used.

SO- 1m focus should have a back-focus of 54.4mm. Your lens actually focuses at 0.85m- 15cm too close, which would requires 54.9mm back-focus.
I would start by reducing the shim by 0.5mm.

And- completely agree about the quality of the images from this lens.
One GOTCHA: the front element protrudes, Canon made special filters for this lens with the glass all the way to the front of the filter. It used a clamp-on hood. If you cannot get the original filters- use a 55-58 step up ring, or tale the glass out of a 55mm filter and use as a spacer.

Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr
Canon 50/1.2, with home-made hood by fiftyonepointsix, on Flickr

I used the clamp from an Olympus rubber hood for the 35~70 zoom, then epoxied a vented 58mm hood into it. About $10, much less expensive that the originals.

Think I have done it.
Right?

 

[tardegard]

I removed that one only shim but it is still front focusing.

 

[tardegard]

Brian, I am afraid a did a mess. I reassembled the front element but now the aperture doesn't work anymore.
Could I please write you in private so that we don't bother the others here?

 

[raid]

Just mail any competent repairman your lens and get it fixed.

 

[former member]

PM Sent.

https://johanniels.com/canon-rf-50mm-1-2-cleaning-leica/

The first step given in Johan's tutorial linked to previously shows the rear retaining ring that needs to come out.

 

[Deleted member 65559]

Just email any competent repairman your lens and get it fixed.

Raid, I've always laughed along with this sign. It amazes me how many items fall prey to attempted home fixes. In the musical instrument world it's about the same. "How hard can it be?" "I'll save money by buying the tools and doing my own fretjobs" "I'm a carpenter so i'll refinish this vintage instrument" Somehow the elements of skill and experience get forgotten in the initial assessment.

Flickr

 

[former member]

The optical barrel is held in the focus mount using a retaining ring, which comes out from the rear. The lens uses a shim- a metal ring. If your lens is front focusing: the shim is too thick. The other possibility is that the optics are out of place in the lens, or the helical in the focus mount is not assembled correctly.

https://johanniels.com/canon-rf-50mm-1-2-cleaning-leica/

The Tutorial linked to before provides good instructions for taking out the retaining ring in the rear of the lens, removing the barrel in one piece from the focus mount revealing the shim. The Canon 50/1.2 often builds up haze on the surface behind the aperture. The tutorial addresses that issue, removing the rear group for access to the surface and for swabbing the aperture blades from behind. I've never had to remove the front group to perform maintenance or adjust an intact lens.

For the lens built from two parts lenses some 12 years ago, one barrel was completely frozen and required a dremel to get the rear group out. Total cost of the two parts lenses was $90. The perfect lens I have now- $400 with a Canon Vt Deluxe.

 

[tardegard]

The Tutorial linked to before provides good instructions for taking out the retaining ring in the rear of the lens, removing the barrel in one piece from the focus mount revealing the shim. The Canon 50/1.2 often builds up haze on the surface behind the aperture. The tutorial addresses that issue, removing the rear group for access to the surface and for swabbing the aperture blades from behind. I've never had to remove the front group to perform maintenance or adjust an intact lens.

For the lens built from two parts lenses some 12 years ago, one barrel was completely frozen and required a dremel to get the rear group out. Total cost of the two parts lenses was $90. The perfect lens I have now- $400 with a Canon Vt Deluxe.

i have sent back mine, I am sorry because I liked it but I messed with the aperture blades and it also had some other issues. I am lucky that the seller took I back.
Thank you for your help Brian, we tried it.