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Flektogon 35/2.8 and Sonnar 135/4 - weird issue
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PostPosted: Fri Apr 28, 2017 7:27 pm    Post subject: Flektogon 35/2.8 and Sonnar 135/4 - weird issue Reply with quote

I have three Flektogons 35/2.8 M42 and one Sonnar 135/4 which share the same weird issue. They're in minty condition, no signs of abuse or disassembly. I focus on infinity and set wide open aperture. Then I focus towards closer objects. At minimal focus distance aperture changes (ring moves while focusing back) one stop. Is it normal? What do you think? I'd have no suspicions if it was one copy, but it's happening again and again.


PostPosted: Sun Apr 30, 2017 6:04 pm    Post subject: Reply with quote

Just tried my zebra 35/2.8 and it does the same, max aperture at MFD is just under f/4 instead of f/2.8. It's probably a feature of the lens. As the effective focal length increases as you approach MFD, the max aperture decreases accordingly and the lens tells you what it is. Very nice, I wasn't aware of that. Most lenses I think don't do that, they just say they're always at f/2.8 or whatever wide open, which is simply not true when you focus closer.

I tried a few others as well. Zebra style Sonnar 135/3.5 has that feature, but black Flektogon 35/2.4 MC, black Flektogon 20/2.8 MC and zebra Pancolar 50/1.8 don't! Don't have any other CZJ lenses.

UPDATE: I can't find any other lenses in my collection other than CZJ 35/28 and 135/3.5 that have this feature. The best candidates would be macros but my Minolta 50/3.5 and 100/4 (both MD-III) don't. They only have EV compensation values printed on the barrel at a few focus positions.


PostPosted: Sun Apr 30, 2017 9:37 pm    Post subject: Reply with quote

Thank you for your effort, Miran. Having a few samples which behave the same we're allowed to claim that this is a feature Smile.
Zebra Flektogon and Sonnar are the only ones that work like that from my entire collection. I wonder what what special with them to have this feature.