Canon 50mm f/1.5 LTM: rear element haze?

[krylovsk]

I've been looking to add a 50mm Sonnar to my kit for a while and a listing with this Canon 50mm f1.5 LTM came up locally with what seems to be haze (?) on the rear element. I don't mind minor issues as long as it's not progressing and not transferring to my other lenses. My chances finding a better copy for the price or a Jupiter-3 in better condition are pretty low anyway.

From what I read online this lens is prone to separation, especially in the rear element group, which is a bit concerning but this does not look like a starting separation to my untrained eye.
The seller does not provide too much detail on what is the issue, but he mentions it in the description and the images are pretty detailed albeit low-res, so I do not expect he is trying to hide something maliciously (he also offers returns).

What do you think this is and what are the chances of it getting worse? I did a bit of research and the lens is more complex than I would trust myself to try cleaning. I also want to use it on film RFs.


haze?


minor oil residuals

 

[fferreres]

I've been looking to add a 50mm Sonnar to my kit for a while and a listing with this Canon 50mm f1.5 LTM came up locally with what seems to be haze (?) on the rear element. I don't mind minor issues as long as it's not progressing and not transferring to my other lenses. My chances finding a better copy for the price or a Jupiter-3 in better condition are pretty low anyway.

From what I read online this lens is prone to separation, especially in the rear element group, which is a bit concerning but this does not look like a starting separation to my untrained eye.
The seller does not provide too much detail on what is the issue, but he mentions it in the description and the images are pretty detailed albeit low-res, so I do not expect he is trying to hide something maliciously (he also offers returns).

What do you think this is and what are the chances of it getting worse? I did a bit of research and the lens is more complex than I would trust myself to try cleaning. I also want to use it on film RFs.


haze?


minor oil residuals

The second looks like separation. But it could also be coating decay. It's likely the element shown is a group. it's clearly not the last element, and this lens should have 2 cemented groups in the rear.

AVOID unless you like the adventure of potentially re-cementing this.

 

[krylovsk]

The second looks like separation. But it could also be coating decay. It's likely the element shown is a group. it's clearly not the last element, and this lens should have 2 cemented groups in the rear.

AVOID unless you like the adventure of potentially re-cementing this.

Got an answer from the seller saying that it’s “tiny bubbles, possibly from the aperture blades oil“.
I read a bit about mysteries of haze in old RF lenses, might indeed be the case and aperture oil played a role in that, not clear how far it could affect the coatings though.

I still think maybe to take it and return if I find signs of separation on closer inspection. That shouldn’t be too difficult to determine, right?

 

[Tom Caldwell]

I don't know about the Canon 50/1.5 in LTM but I do know about their 50/1.2, 50/1.4 and 50/1.8 in ltm.

The first two seem to get a bit of haze on the first element surface after the aperture which can be cleaned off. The 50/1.8 seems to suffer from etched haze on the same surface which cannot be fixed - excessive cleaning of this surface just seems to render it completely opaque eventually.

I bought three Canon 50/1.8 LTM lenses quite cheaply - they all was described as "having some haze". The worst and cheapest had surface completely destroyed. The best is not too bad, but I should check my little collection again.

What I think happens is that these lenses might have been stored object lens up for periods of time. Fluctuating temperatures causes some aperture lubricant to vapourize and become deposited on the next lower surface of the optics.

The 50/1.8 may well have had a softer surface coating than the others which the deposited lubricant destroys in time.

That is my guess.

Luckily the lenses are very easy to service and clean the offending surface.

Maybe very careful cleaning might work on the 50/1.8 but I am not completely sure that the surface is actually being destroyed by the deposits from the aperture.

 

[Tons o Glass]

I've been looking to add a 50mm Sonnar to my kit for a while and a listing with this Canon 50mm f1.5 LTM came up locally with what seems to be haze (?) on the rear element. I don't mind minor issues as long as it's not progressing and not transferring to my other lenses. My chances finding a better copy for the price or a Jupiter-3 in better condition are pretty low anyway.

From what I read online this lens is prone to separation, especially in the rear element group, which is a bit concerning but this does not look like a starting separation to my untrained eye.
The seller does not provide too much detail on what is the issue, but he mentions it in the description and the images are pretty detailed albeit low-res, so I do not expect he is trying to hide something maliciously (he also offers returns).

What do you think this is and what are the chances of it getting worse? I did a bit of research and the lens is more complex than I would trust myself to try cleaning. I also want to use it on film RFs.


haze?


minor oil residuals

The second looks like separation. But it could also be coating decay. It's likely the element shown is a group. it's clearly not the last element, and this lens should have 2 cemented groups in the rear.

In the first image I see the oil-splatter type blemishes (which may or may not be in the balsam or on one or both of the surfaces the balsam couples), but in this second image, I don't see the splatter, or any defects at all for that matter - all I see is a couple overlapped reflections of something in the background [one inverted, one not]).

AVOID unless you like the adventure of potentially re-cementing this.

I hope to try my hand at re-cementing someday. I've only gotten so far as trying to re-flow balsam in the oven (groups from a separation-prone DKL-mount Septon 50/2), which is one of the first steps of that whole process.

 

[fferreres]

The second looks like separation. But it could also be coating decay. It's likely the element shown is a group. it's clearly not the last element, and this lens should have 2 cemented groups in the rear.

AVOID unless you like the adventure of potentially re-cementing this.

Got an answer from the seller saying that it’s “tiny bubbles, possibly from the aperture blades oil“.
I read a bit about mysteries of haze in old RF lenses, might indeed be the case and aperture oil played a role in that, not clear how far it could affect the coatings though.
I still think maybe to take it and return if I find signs of separation on closer inspection. That shouldn’t be too difficult to determine, right?

Oftentimes, these defects could be inconsequential, hard to notice any degradation in actual images. I have a Summicron that has something that resembles this. The surface facing the aperture from the rear block has these small circular places where upon shining a bright light, will bounce or reflect while some other parts of the surface just transmit. So it's entirely possible it may be some reaction from the gas stemming from the oil condensing and reacting with the coating.

It's a hard choice to make. With the Summicron, I only noticed it much later and I wasn't sure if the seller knew of it. If I had though the person concealed it, I would have returned it. The other aspect...the lens works perfectly well. I know because I have another perfectly good Summicron.

Oftentimes, it's best to ask for some additional photos, and make sure that whatever you do, you aren't left with feeling you missed out, or have buyer remorse.

 

[Tom Caldwell]

We are talking about the f1.8 presumably as I don't think such a lens as and S-Series f1.5 exists.

The f1.8 lens is prone to etched haze on the first surface behind the aperture whilst the f1.4 haze in the same place seems to be capable of being cleaned off without surface damage (but maybe I just got lucky there).

The 50/1.8 ltm was made in three different series and maybe I was just unlucky with mine. But if a 50/1.5 exists then I have had no experience with it.

 

[krylovsk]

We are talking about the f1.8 presumably as I don't think such a lens as and S-Series f1.5 exists.

The f1.8 lens is prone to etched haze on the first surface behind the aperture whilst the f1.4 haze in the same place seems to be capable of being cleaned off without surface damage (but maybe I just got lucky there).

The 50/1.8 ltm was made in three different series and maybe I was just unlucky with mine. But if a 50/1.5 exists then I have had no experience with it.

Canon 50/1.5 LTM exists and the one I posted above is on the way to me The 50/1.5 was introduced in 1952 under "Canon lens" branding (not Serenar). They didn't make too many of them and the production was seized in 1956, some say because it was difficult in manufacturing.

What makes it interesting to me is that it's a Sonnar design lens in LTM, one with excellent engineering (vs Jupiter-3) that doesn't cost too much (vs Zeiss or Nikkor). It seems that the haze issue it suffers from is similar to what you describe with f1.8 and f1.4 lenses.

Depending on how bad the haze is and how much I like the lens I'll need to decide whether to return or keep it, and then whether to clean or just leave it be. I'll post my findings and hopefully some images when the lens arrives.

 

[Tom Caldwell]

We are talking about the f1.8 presumably as I don't think such a lens as and S-Series f1.5 exists.

The f1.8 lens is prone to etched haze on the first surface behind the aperture whilst the f1.4 haze in the same place seems to be capable of being cleaned off without surface damage (but maybe I just got lucky there).

The 50/1.8 ltm was made in three different series and maybe I was just unlucky with mine. But if a 50/1.5 exists then I have had no experience with it.

Canon 50/1.5 LTM exists and the one I posted above is on the way to me The 50/1.5 was introduced in 1952 under "Canon lens" branding (not Serenar). They didn't make too many of them and the production was seized in 1956, some say because it was difficult in manufacturing.

What makes it interesting to me is that it's a Sonnar design lens in LTM, one with excellent engineering (vs Jupiter-3) that doesn't cost too much (vs Zeiss or Nikkor). It seems that the haze issue it suffers from is similar to what you describe with f1.8 and f1.4 lenses.

Depending on how bad the haze is and how much I like the lens I'll need to decide whether to return or keep it, and then whether to clean or just leave it be. I'll post my findings and hopefully some images when the lens arrives.

Thanks. It must have been a predecessor of the others (perhaps). I knew about the others and the more (infamous) f1.0 or was it f0.95 version? But I was curious about a f1.5. I even tried looking it up on the "Canon Museum" site with no luck - maybe I was using an incorrect search question.

I tend not to remember the source of the information that I pick up through rambles around the internet. But I do have a garbled memory of a mention of a Leica aperture lubricant that was used that was prone to causing haze when evaporated. Whether or not it caused glass surface etching I don't remember. But there was something in this half remembered comment that indicated that early Canon had used the same lubricant.

One of my two excursions into buying Leica was a cheap Hektor 135mm lens in perfect condition which turned out to have terrible haze. I was reluctant to pull a "precious" Leica lens apart but eventually did so. It turned out to be easy to work on and the haze cleaned off very easily.

Likewise my Canon--S 50mm lenses all had haze of some sort or another 1 x f1.2 (trifling developed some time after purchase) 1 x 1.4 (a little) 3 f1.8 (varied from one minor to two with actual etched glass). This I have already made comment on. Only on the two really bad f1.8 lenses did the haze amount to etching the glass itself. On the faster lenses the haze (that there was) cleaned off easily.

My guess was than a softer surface lens was used on at least some of the f1.8 lenses - there were apparently three. series according to the Canon Museum. I would have to re-find the lenses to be sure of a more precise identification. In any case none of them is "your" lens. All these "S" series 50mm lenses were also quite easy to disassembly from behind the aperture.

 

[krylovsk]

Thanks. It must have been a predecessor of the others (perhaps). I knew about the others and the more (infamous) f1.0 or was it f0.95 version? But I was curious about a f1.5. I even tried looking it up on the "Canon Museum" site with no luck - maybe I was using an incorrect search question.

I tend not to remember the source of the information that I pick up through rambles around the internet. But I do have a garbled memory of a mention of a Leica aperture lubricant that was used that was prone to causing haze when evaporated. Whether or not it caused glass surface etching I don't remember. But there was something in this half remembered comment that indicated that early Canon had used the same lubricant.

One of my two excursions into buying Leica was a cheap Hektor 135mm lens in perfect condition which turned out to have terrible haze. I was reluctant to pull a "precious" Leica lens apart but eventually did so. It turned out to be easy to work on and the haze cleaned off very easily.

Likewise my Canon--S 50mm lenses all had haze of some sort or another 1 x f1.2 (trifling developed some time after purchase) 1 x 1.4 (a little) 3 f1.8 (varied from one minor to two with actual etched glass). This I have already made comment on. Only on the two really bad f1.8 lenses did the haze amount to etching the glass itself. On the faster lenses the haze (that there was) cleaned off easily.

My guess was than a softer surface lens was used on at least some of the f1.8 lenses - there were apparently three. series according to the Canon Museum. I would have to re-find the lenses to be sure of a more precise identification. In any case none of them is "your" lens. All these "S" series 50mm lenses were also quite easy to disassembly from behind the aperture.

According to that article I posted above, it is indeed the predecessor of the other faster 50s: f1.2 (1956), f1.4 (1957), and f0.95 (1961). Btw, here's 50/1.5 in Canon museum.

If one of your 50/1.8s was all-silver then as I understand it must be of the same period as the f1.5 (1951-1956) as all later 50/1.8s had some black elements in their body design. Now I didn't look as far as at which facilities they were manufactured, but I think we can assume they've used the same aperture lubricant. Whether or not it has etched the lens surface is probably up to the lens surface / coatings as you say, and if earlier lenses had softer surfaces that doesn't sound good for my case.

I haven't worked on RF lenses before and I also want to use it on RF film cameras, so I'm mostly concerned not to mess up the collimation. Getting to that lens surface shouldn't be too difficult though as I only need to take out the rear elements block that sits behind the aperture blades. As I understand the collimation is up to the shim, but one needs to be careful when unscrewing the blocks from optical assembly and it's best to leave marks for re-tightening later. I've got myself a Jupiter-8 that definitely needs re-lubrication, so I have a RF sonnar lens to practice on.