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Topcor love and hate: advice needed
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PostPosted: Sat Jul 04, 2020 5:03 am    Post subject: Topcor love and hate: advice needed Reply with quote
Sorry I know the title is exaggerated. But sadly it is true for me.

I love Topcor lenses, very unique rendering among lenses made in Japan in old days. However, in my small collection of Topcor lenses, 35mm f/2.8 (two copies), 100mm f/2.8, 135mm f/2.8, 58mm f/1.4. All but the 135mm are stuck open (not full stuck, though). Here is what happened.


#1 This is f22, aperture hole is correctly set.



#2 This is f2.8, which is ok.



#3 This is from f2.8 to f22. Notice the position of the tab in the blue circle. It doesn't move to the location in Photo. 1. I had to manually
move it to the end to make the aperture blades close to f22, shown in Photo. 1. Otherwise, the lens is stuck open.



The aperture blades in all the lenses have oil. My question is: what causes stuck blades at wide open? Can it be fixed if the oil is cleaned? Or some spring inside the aperture assembly loses strength over time and needs to be replaced?

Appreciate any information!


PostPosted: Sat Jul 04, 2020 11:59 am    Post subject: Reply with quote
Could be sticky blades if you ask me.


PostPosted: Sat Jul 04, 2020 12:56 pm    Post subject: Reply with quote
Oil on the blades does slows down or completely stuck the blades yes (or leaves them partially opened/closed), the return spring isn t very loaded. Oil on the blades almost always means that there is also oil on the actuation mechanism. Cleaning is the only way to make it work again, i don t know if you work on the lenses but the Topcors are not overly complicated to work on, for example you can remove the optical block (including the aperture mechanism) without having to dismantle the focusing helicoids. For a full cleaning it s better to remove the blades though, putting them back requires a bit of skill. Those are not full tutorials, but they ll give you an idea:

http://pakira3.sakura.ne.jp/wp/?s=topcor


PostPosted: Sat Jul 04, 2020 4:05 pm    Post subject: Reply with quote
caspert79 wrote:
Could be sticky blades if you ask me.


tomasg wrote:
Oil on the blades does slows down or completely stuck the blades yes (or leaves them partially opened/closed), the return spring isn t very loaded. Oil on the blades almost always means that there is also oil on the actuation mechanism. Cleaning is the only way to make it work again, i don t know if you work on the lenses but the Topcors are not overly complicated to work on, for example you can remove the optical block (including the aperture mechanism) without having to dismantle the focusing helicoids. For a full cleaning it s better to remove the blades though, putting them back requires a bit of skill. Those are not full tutorials, but they ll give you an idea:

http://pakira3.sakura.ne.jp/wp/?s=topcor


Thanks guys for your information. I just wasn't sure if the spring is still strong enough so that after the blades are cleaned, the aperture can still function well. If it is the spring that loses its elasticity, then a replacement or shortening of it would be needed. The replacement part could be hard to find, or cutting part of the spring could also be not that straightforward.


PostPosted: Sat Jul 04, 2020 6:29 pm    Post subject: Reply with quote
FWIW, I have managed to clean blades without removing them. I used naphtha and a cotton swab. It took a good deal of patience, cleaning then opening and closing the aperture, then cleaning again over and over and over, but it worked in the end. This was an aperture that was completely stuck wide open.

Removing the blades and giving them a proper soaking is unquestionably better, especially if they're heavily oiled, but acceptable results are possible if you don't want to do that for some reason.


PostPosted: Sat Jul 04, 2020 7:00 pm    Post subject: Reply with quote
KEO wrote:
FWIW, I have managed to clean blades without removing them. I used naphtha and a cotton swab. It took a good deal of patience, cleaning then opening and closing the aperture, then cleaning again over and over and over, but it worked in the end. This was an aperture that was completely stuck wide open.

Removing the blades and giving them a proper soaking is unquestionably better, especially if they're heavily oiled, but acceptable results are possible if you don't want to do that for some reason.


Yes, that can work too, and with a bit of luck the oil doesn t come back. People are afraid to remove and than put back the aperture blades, but if one has reasonable access it s not that difficult to do, the number of blades doesn t make a big difference, it s always te last one that is difficult because it has to go under the first one, the right tweezers are essential, the very thin, needle like ones work for me.


PostPosted: Sat Jul 04, 2020 8:31 pm    Post subject: Re: Topcor love and hate: advice needed Reply with quote
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Last edited by Blazer0ne on Tue Feb 22, 2022 6:50 pm; edited 1 time in total


PostPosted: Sat Jul 04, 2020 8:55 pm    Post subject: Re: Topcor love and hate: advice needed Reply with quote
Blazer0ne wrote:
Also, some Topcor aperture assemblies pop right out and can be dropped into a naphtha bath without the need to touch any blades. Given the proper heat and drying time it can be very easy task.


That's good to know. Thanks.


PostPosted: Mon Jul 06, 2020 12:23 am    Post subject: Re: Topcor love and hate: advice needed Reply with quote
Blazer0ne wrote:
vivaldibow wrote:


The aperture blades in all the lenses have oil. My question is: what causes stuck blades at wide open? Can it be fixed if the oil is cleaned? Or some spring inside the aperture assembly loses strength over time and needs to be replaced?

Appreciate any information!


Having sticky blades can bend or wear down the linkage beneath the bayonet mount. A loose rear mount can also allow for some issues in the connection. If that is not the case maybe shim or tape the offending tab to perform as needed.

Also, some Topcor aperture assemblies pop right out and can be dropped into a naphtha bath without the need to touch any blades. Given the proper heat and drying time it can be very easy task.


Thanks. All noted.
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