Unusual adaptall aperture issue
When using viewfinder stop-down preview I see an aperture issue that does not happen when using the green button (in modes where this stops down momentarily to meter).
With lens aperture set to AE:
1) Green button works flawlessly as expected:
- Aperture constricts and then re-opens to full dilation. Every time.
2) Stop-down preview fails ~50% of the time:
- First press will usually constrict, but often not to the correct aperture, and then re-open, but often not to fully open.
- Second press usually constricts, usually to the correct aperture, and then re-open, usually to fully open.
With lens aperture set to any manual aperture (not AE):
1) Green button works flawlessly as expected:
2) Stop-down preview works flawlessly as expected:
Has this problem been seen before?
Suggestions?
K-5 v1.13
Tamron Adaptall PK/A adapters (I have 2, they were obtained separately and yet both behave the same way)
lenses tested:
Tamron 300mm/2.8 (60B)
Tamron 70-210mm/3.5 (19AH)
Both adapters and the 60B's internal springs, moving parts, rollers and contacts look to be in excellent condition with no sticking or corrosion (I have had them disassembled, yes).
Most likely to happen with apertures between f/16 and f/6.3.
Yes, I understand how to use adaptall adapters and the in AE/manual aperture modes :)
No, this is not related to the "'F--' intermittently displayed due to non-conductive screw coating next to the contacts" issue.
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