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Topcor 10cm: focus ring stuck or there is trick
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PostPosted: Sat Feb 23, 2019 8:03 pm    Post subject: Topcor 10cm: focus ring stuck or there is trick Reply with quote
Just received this Auto Topcor 10cm f/2.8. The aperture mechanism seems complicated but it works. The focus ring
seems stuck: there is no way for me to rotate it. Is the ring stuck or there is a trick to rotate the focus ring? This is
the first Topcor lens I had. Thanks!



PostPosted: Sat Feb 23, 2019 9:22 pm    Post subject: Reply with quote
Sorry to hear your first experience with Topcor is not a good one, but the lens is quite old, the Topcon R was launched in 1957.
The focus ring should be free to turn at all times, so it will need to be serviced, it's probably dried grease that's very stiff, it's possible that it's seized or sand or other contaminate got into the helicoid so I'd be careful about forcing it.


PostPosted: Sat Feb 23, 2019 11:04 pm    Post subject: Reply with quote
Lightshow wrote:
Sorry to hear your first experience with Topcor is not a good one, but the lens is quite old, the Topcon R was launched in 1957.
The focus ring should be free to turn at all times, so it will need to be serviced, it's probably dried grease that's very stiff, it's possible that it's seized or sand or other contaminate got into the helicoid so I'd be careful about forcing it.


Thanks for the confirmation. It looks like the focus is stuck. How hard is to fix it? I tried to fix the stuck focus of a Spiratone 135mm f/2.8 but haven't got a clue yet after simply unscrewing the three set screws.

By the way, is this Auto Topcor 10cm f/2.8 same as the later RE auto topcor 10cm f/2.8 optically?


PostPosted: Sun Feb 24, 2019 6:51 pm    Post subject: Reply with quote
vivaldibow wrote:
Lightshow wrote:
Sorry to hear your first experience with Topcor is not a good one, but the lens is quite old, the Topcon R was launched in 1957.
The focus ring should be free to turn at all times, so it will need to be serviced, it's probably dried grease that's very stiff, it's possible that it's seized or sand or other contaminate got into the helicoid so I'd be careful about forcing it.


Thanks for the confirmation. It looks like the focus is stuck. How hard is to fix it? I tried to fix the stuck focus of a Spiratone 135mm f/2.8 but haven't got a clue yet after simply unscrewing the three set screws.

By the way, is this Auto Topcor 10cm f/2.8 same as the later RE auto topcor 10cm f/2.8 optically?

I believe they are the same optically, perhaps the single layer anti reflection coating is improved.
From the Topcon Story:
RE, Auto Topcor 100mm f2.8
It's 5 Element 3 group construction was derived from the old Topcon 100...

Which I understand it to mean that it's optically the same but that the body has been updated. It says basically the same thing with the F auto Topcor 100.

How hard to fix? well I do know these lenses with ears are relatively complex, gears springs and levers, I've not taken a Topcor version apart so I don't really know how bad/hard it will be, I have opened up Topcor R's and RE's and they were relatively strait forward.

The CZJ Flek 35mm with the ear was complex, it had a number of issues in the ear so I hacked it off and made it fully manual and epoxied a plastic cover over the opening.
I'm tempted to do the same to the 3.5cm and 5.8cm auto's to match my presets, only I would feel bad about hacking into a Topcor.


PostPosted: Sun Feb 24, 2019 7:44 pm    Post subject: Reply with quote
It could still be used on mirrorless cameras with an exakta - m42 adapter and m42 helicoid.
I have just bought an adapter that converts exakta to m42 but have not tested it yet.


PostPosted: Sun Feb 24, 2019 11:20 pm    Post subject: Reply with quote
I started a similar thread a couple of weeks ago regarding a Tamron Twin-Tele I'd acquired with a similar set of symptoms, working aperture but stuck focus.
Resolving the issue involved removing the glass and soaking what was left in acetone for several days, whilst intermittently (every day or two) subjecting the assembly to the heat of boiling water from a kettle. It finally all came free and I was able to clean out the old grease and re-lubricate it.
One response I received mentioned actually boiling the mechanism (with the glass removed) in a pan of water until it loosened up. I didn't need to get quite that extreme, but can see it working! Remember to wear rubber gloves if working with boiling water and take appropriate care when working with volatile solvents!

Good luck Smile


PostPosted: Sun Feb 24, 2019 11:56 pm    Post subject: Reply with quote
blotafton wrote:
It could still be used on mirrorless cameras with an exakta - m42 adapter and m42 helicoid.
I have just bought an adapter that converts exakta to m42 but have not tested it yet.


That's right, but you won't reach infinity as M42 is 0.76 mm too long. Better to use the right Exakta adapter with correct 44.7 mm register distance. I haven't seen any M42 helicoid adapter which is able to go below the M42 register distance of 45.46 mm.
Is there any? I would be interested as I have such Exakta to M42 rings as well.


PostPosted: Mon Feb 25, 2019 12:25 am    Post subject: Reply with quote
tb_a wrote:
blotafton wrote:
It could still be used on mirrorless cameras with an exakta - m42 adapter and m42 helicoid.
I have just bought an adapter that converts exakta to m42 but have not tested it yet.


That's right, but you won't reach infinity as M42 is 0.76 mm too long. Better to use the right Exakta adapter with correct 44.7 mm register distance. I haven't seen any M42 helicoid adapter which is able to go below the M42 register distance of 45.46 mm.
Is there any? I would be interested as I have such Exakta to M42 rings as well.


There are thin ones, I have 3. 25-55mm, 17-31mm and 12-17mm. Combined with a 1mm m42 to E mount. Exakta lenses should work.
The negative thing is that the m42 adapter is supposed to be attached to the Exakta lens with 3 small pointed screws from the side. It might leave marks, or worse the lens falls off.
But it might also work fine.
Here is the kind of adapter:



PostPosted: Mon Feb 25, 2019 1:48 am    Post subject: Reply with quote
blotafton wrote:
There are thin ones, I have 3. 25-55mm, 17-31mm and 12-17mm. Combined with a 1mm m42 to E mount. Exakta lenses should work.
The negative thing is that the m42 adapter is supposed to be attached to the Exakta lens with 3 small pointed screws from the side. It might leave marks, or worse the lens falls off.


OK, the thin 1mm M42 to NEX adapter is new to me. The rest was clear anyway.
Thanks for the information.
Not to sure if that's really better than my ready Exakta to NEX or Leica-M adapters as the Exakta to M42 rings indeed don't really look trustworthy.


PostPosted: Mon Feb 25, 2019 2:19 am    Post subject: Reply with quote
I believe they are the same optically, perhaps the single layer anti reflection coating is improved.
From the Topcon Story:
RE, Auto Topcor 100mm f2.8
It's 5 Element 3 group construction was derived from the old Topcon 100...

Which I understand it to mean that it's optically the same but that the body has been updated. It says basically the same thing with the F auto Topcor 100.

How hard to fix? well I do know these lenses with ears are relatively complex, gears springs and levers, I've not taken a Topcor version apart so I don't really know how bad/hard it will be, I have opened up Topcor R's and RE's and they were relatively strait forward.

The CZJ Flek 35mm with the ear was complex, it had a number of issues in the ear so I hacked it off and made it fully manual and epoxied a plastic cover over the opening.
I'm tempted to do the same to the 3.5cm and 5.8cm auto's to match my presets, only I would feel bad about hacking into a Topcor.[/quote]

Thanks. From the size of those 10cm f/2.8, I guess the optics is the same.

I watched some youtube video on how to re-grease the focus ring and found that involved quite some work. I might not want to risk on this one. Sad


PostPosted: Mon Feb 25, 2019 2:20 am    Post subject: Reply with quote
blotafton wrote:
It could still be used on mirrorless cameras with an exakta - m42 adapter and m42 helicoid.
I have just bought an adapter that converts exakta to m42 but have not tested it yet.


Thanks. That's an interesting idea. I happen to have an m42 helicoid 17-31mm and an m42-nex. All I need is an exa - m42.


PostPosted: Mon Feb 25, 2019 2:22 am    Post subject: Reply with quote
kypfer wrote:
I started a similar thread a couple of weeks ago regarding a Tamron Twin-Tele I'd acquired with a similar set of symptoms, working aperture but stuck focus.
Resolving the issue involved removing the glass and soaking what was left in acetone for several days, whilst intermittently (every day or two) subjecting the assembly to the heat of boiling water from a kettle. It finally all came free and I was able to clean out the old grease and re-lubricate it.
One response I received mentioned actually boiling the mechanism (with the glass removed) in a pan of water until it loosened up. I didn't need to get quite that extreme, but can see it working! Remember to wear rubber gloves if working with boiling water and take appropriate care when working with volatile solvents!

Good luck Smile


Thanks for the info. I saw your post the other day! So far I've only tried to remove the very front glass and very rear glass of some other lenses. For anything in between, I haven't had any clue yet. I'll see.


PostPosted: Mon Feb 25, 2019 7:51 am    Post subject: Reply with quote
[quote="blotafton"]
tb_a wrote:
blotafton wrote:
It could still be used on mirrorless cameras with an exakta - m42 adapter and m42 helicoid.
I have just bought an adapter that converts exakta to m42 but have not tested it yet.

The negative thing is that the m42 adapter is supposed to be attached to the Exakta lens with 3 small pointed screws from the side. It might leave marks, or worse the lens falls off.
But it might also work fine.
Here is the kind of adapter:



I bought one of these adaptors ... definitely not perfect! I had to drill three small recesses into the lens bayonet to accept the grub screws, else they protruded too much and fouled the camera thread. Getting everything lined up so's the lens index was neatly on the top when mounted was a real fiddle. Also the original lens locking pin needs to be removed (try not to lose it if you choose to revert!)

Far more satisfactory was to use a mirrorless body with an adaptor designed for the job and get infinity focus as well Smile


PostPosted: Mon Feb 25, 2019 8:29 am    Post subject: Reply with quote
kypfer wrote:
I bought one of these adaptors ... definitely not perfect! I had to drill three small recesses into the lens bayonet to accept the grub screws, else they protruded too much and fouled the camera thread. Getting everything lined up so's the lens index was neatly on the top when mounted was a real fiddle. Also the original lens locking pin needs to be removed (try not to lose it if you choose to revert!)

Far more satisfactory was to use a mirrorless body with an adaptor designed for the job and get infinity focus as well Smile


Same experience here. As these ready adapters like Exakta to NEX are nowadays available for only EUR 12.- incl. shipping it doesn't really make sense. I've only experimented with these M42 rings when adapting to DSLR. For mirrorless there are definitely better solutions.


PostPosted: Mon Feb 25, 2019 12:05 pm    Post subject: Reply with quote
tb_a wrote:
kypfer wrote:
I bought one of these adaptors ... definitely not perfect! I had to drill three small recesses into the lens bayonet to accept the grub screws, else they protruded too much and fouled the camera thread. Getting everything lined up so's the lens index was neatly on the top when mounted was a real fiddle. Also the original lens locking pin needs to be removed (try not to lose it if you choose to revert!)

Far more satisfactory was to use a mirrorless body with an adaptor designed for the job and get infinity focus as well Smile


Same experience here. As these ready adapters like Exakta to NEX are nowadays available for only EUR 12.- incl. shipping it doesn't really make sense. I've only experimented with these M42 rings when adapting to DSLR. For mirrorless there are definitely better solutions.


Not optimal!


PostPosted: Mon Feb 25, 2019 8:48 pm    Post subject: Reply with quote
There are M42 focusing adapters that work at less than 45.46mm. This for Sony: 272637419700 (17-31mm) and this 401073085974 (27-59mm). Ebay codes.


PostPosted: Tue Feb 26, 2019 4:22 pm    Post subject: Reply with quote
Well, I've never worked on (or owned) any of the original Auto-Topcon lenses. But I suspect the general design is the same as the RE. Auto-Topcor lenses. The basic design is that there's an inner block consisting of the aperture mechanism, which has the front and rear optical blocks screwed into it. It's placed into the focusing helical assembly with a selected spacer, and then held in from the front by a retaining ring. The aperture mechanism has an arm coming up from the rear of the lens to control the aperture.

On the RE. Auto-Topcors, you start by removing the beauty ring and the filter ring. The filter ring is held in by three set-screws on the sides, below the filter ring. That will expose the outermost retaining ring, which is what's holding the inner block in place.

But I don't see any of those set-screws on your Auto-Topcor. Perhaps they are behind the focusing ring. It's obvious that you can remove the focusing ring by loosening three set-screws. That may well expose more set-screws to open up the front of the lens.

I would try and avoid going in from the back -- lots of moving parts and "cocked" springs in that auto-aperture mechanism.


PostPosted: Wed Feb 27, 2019 6:38 am    Post subject: Reply with quote
John Shriver wrote:
Well, I've never worked on (or owned) any of the original Auto-Topcon lenses. But I suspect the general design is the same as the RE. Auto-Topcor lenses. The basic design is that there's an inner block consisting of the aperture mechanism, which has the front and rear optical blocks screwed into it. It's placed into the focusing helical assembly with a selected spacer, and then held in from the front by a retaining ring. The aperture mechanism has an arm coming up from the rear of the lens to control the aperture.

On the RE. Auto-Topcors, you start by removing the beauty ring and the filter ring. The filter ring is held in by three set-screws on the sides, below the filter ring. That will expose the outermost retaining ring, which is what's holding the inner block in place.

But I don't see any of those set-screws on your Auto-Topcor. Perhaps they are behind the focusing ring. It's obvious that you can remove the focusing ring by loosening three set-screws. That may well expose more set-screws to open up the front of the lens.

I would try and avoid going in from the back -- lots of moving parts and "cocked" springs in that auto-aperture mechanism.


Thanks for the detailed information!
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