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What's the latest lens you repaired yourself?
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PostPosted: Fri Dec 16, 2022 2:17 pm    Post subject: Reply with quote
I'll take your word for it, but it sure looked like tar. And given your description of it, sounds like that's what it was -- cuz it was definitely not easy to remove. I suspect tar would have come off much easier, actually.


PostPosted: Sat Jan 28, 2023 5:56 am    Post subject: Reply with quote
No where near as technical as the above, but still a success for me.



Nikkor-S 35mm f2.8 converted to A/I finally.

This was not an easy conversion. This early Nikkor SLR lens is without bayonet screws, and threads on to the lens body. There is a screw on the back of the aperture ring that links to the aperture mechanism. The aperture ring turns in it's threads during normal use, which is sort of ingenious, with the retaining screw limiting movement.
The rim of the aperture ring actually slides under the linking tab on the D-810, but hangs up on the tab on my extension tube set.



The ring extension shown was actually made out of a plastic spice jar lid, and is just hanging loose, before final adjustment here.

With the limited tools I have here, the usual needle file opening of the aperture ring is sufficient. I filed through the plastic as well, for lack of precision cutting tools.

End result looks absolutely awful and ugly, but like the man said, it works, and properly as well.
I will be doing this again, hopefully a bit neater, when I can find a donor 55mm filter ring to cut up and do the job properly with.

-D.S.


PostPosted: Sun Mar 12, 2023 7:24 pm    Post subject: Reply with quote
... a badly de-centered Canon EF 1.4/50mm I had "saved" many years ago from the wastebin of a photo store. Given the fact that it's de-centering was so bad, I didnt' try to repair it, ever. Some days ago - afterthe celaning of the Canon TS-E4/17mm - I became curious about the construction ofthe EF 1.4/50mm and decided to open it. Pretty interesting, compared to the vintage stuff I usually try to repair!

Long story short end - I was able to repair it, surprisingly. Conclusion: Metal is not always better than plastics ...

I can publish the story (including images) if someone is interested.

S


PostPosted: Sun Mar 12, 2023 8:56 pm    Post subject: Reply with quote
stevemark wrote:
... a badly de-centered Canon EF 1.4/50mm I had "saved" many years ago from the wastebin of a photo store. Given the fact that it's de-centering was so bad, I didnt' try to repair it, ever. Some days ago - afterthe celaning of the Canon TS-E4/17mm - I became curious about the construction ofthe EF 1.4/50mm and decided to open it. Pretty interesting, compared to the vintage stuff I usually try to repair!

Long story short end - I was able to repair it, surprisingly. Conclusion: Metal is not always better than plastics ...

I can publish the story (including images) if someone is interested.

S


Like 1

Absolutely, metal is not always better than plastics.

The whole metal vs. plastic debate in cameras & optics often misses the point completely. So many engineering & practical factors are involved.

Metal generally has the advantage in terms of durability.

The sheer weight of brass parts in particular is often overlooked (helicoids!). The rigidity and dimensional stability of glass-filled polymers is often underestimated, as is the tendency for polymers to build up a static surface charge.

The cost of producing injection moulded plastic parts is also often underestimated; the use of quality engineering plastics is often not a choice of cost-cutting. Injection moulds for glass-filled polymer precision parts in particular are expensive to design and manufacture, and have a relatively short service-life (i.e. they need frequent re-tooling and/or replacement.)

And the list goes on... Wink


PostPosted: Mon Mar 13, 2023 1:25 am    Post subject: Reply with quote
AGFA Color Solinar. Cleaned fungus from 3rd element. Cleaned inside and regreased helicoid
Very easy to assemble/take apart


PostPosted: Sun Mar 19, 2023 3:19 am    Post subject: Reply with quote
RokkorDoctor wrote:

The cost of producing injection moulded plastic parts is also often underestimated; the use of quality engineering plastics is often not a choice of cost-cutting. Injection moulds for glass-filled polymer precision parts in particular are expensive to design and manufacture, and have a relatively short service-life (i.e. they need frequent re-tooling and/or replacement.)

And the list goes on... Wink


Yeah, that was pretty evident when discussing such choices with some Sony engineers. The A900 mirror box is made from carbon-fiber-reinforced polymers (unlike in previous "Sony-Minolta" DSLRs such as the A100 and A700), not only because of its strength, but because of its low thermal expansion. Weight / strength (even though better than metall as well) were not the main reason to go for CFRP I was told, but the low thermal expansion: This was important to keep the "backfocus" AF problems low (remember them ...?). The A900 AF system indeed was very stable - no need for ongoing "backfocus" corrections, neither in cold (-10°C) nor in very hot (>50°C) weather conditions.

Similar story about the famous Tamron vs Sony 2.8/28-75mm "siblings". Everyone says they are the same lens - Sony lens chief designer however, in a personal meeting, told me that the Sony version uses a much more stable & expensive polymer than the Tamron version, along with different (proprietary) chips and software for faster & more precise AF, etc. Quite a few differences between the two incarnations! Which makes the price difference accaptable.

S
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