Summaron 35mm f2.8 Aperture Blades...

micromoogman

micromoogman

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Hi, I have a Summaron 35/2.8 which does not fully open the aperture blades @ f2.8. After dismantling the lens I see that the blades are fully extented, they touch the barrel. I can't see that they could be installed in some other way. What's wrong?

sum_apt.jpg
 
Or are they upside down? I followed Thomas Tomosy repair manual... "install blades in a counter-clockwise direction, narrow tips first"
 
I cannot help with a technical solution, but what I can contribute is: the way the aperture opening looks like (scalloped, not round), is the way f4 looks on the Summaron. All other f-stops are more or less round, but f4 is wildly scalloped.
Wish you all the best assembling the lens, the Summaron 2.8 is a great, great lens.
 
The first post picture looks right to me, when you have everything on the lens built up can you see the blades when you look through the lens? Just put mine at 2.8 and I can't see the blades unless I tilt the lens but when I do they look like the first photo.
 
Ljós said:
I cannot help with a technical solution, but what I can contribute is: the way the aperture opening looks like (scalloped, not round), is the way f4 looks on the Summaron. All other f-stops are more or less round, but f4 is wildly scalloped.
Wish you all the best assembling the lens, the Summaron 2.8 is a great, great lens.
Click to expand...

Yes, it is the same on mine...!
 
OK, it worked! The lens groups actually covers the protruding blades, when installed there's now a clean perfect circle. So my guess is that that inner yoke or what is called was one step off.

sum_apt3.jpg
 
Cool! Congrats! Keep us posted when the lens was completely resuscitated :) The number of Summarons in this world is finite, mankind can't afford to lose any of them :)
 
Thanks! I put it all back together. The only issue now is that it's pretty hard to focus. I have used very light silicone grease, and very little, but still very firm. I noticed that the aluminum threads had some burrs... Any tips on lubing to get the right and butter feel movement?

sum_apt4.jpg
 
There should be a law against posting close-ups of Summarons. I miss mine! :)

Don't know about the focusing issue, except that I hear helicoids can be threaded ("started") at different points.
 
Personally I wouldn't use a silicon grease*. I've got an old container of stuff from National Camera. I'd assume something similar is available from Micro-Tools.

*I also don't know that using something else would solve your problem.
 
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