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04-23-2019, 07:31 PM   #16
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I think I lied. Fiddled more with the 100mm one lens on the "good" body (30k shutter count) and got the same results. Posted a couple of more images to the same zenfolio link above.

Because it's happening with every lens I've had on the thing, and on four bodies, I hardly know what to think.

Try other lenses? All my lenses?

I'm wondering if I've set it to mis-meter somehow. It also doesn't happen every burst. Ugh ugh ugh. Confuseder.

04-23-2019, 09:36 PM - 1 Like   #17
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Tie down the loose ends...
  • Visually inspect the aperture actuator lever for damage
  • Manually test the iris mechanism on the lens by observing the blades from the lens rear while flicking the actuator lever. The blade action should be snappy with NO hesitation or sticking.
  • If the lens has an aperture ring, repeat the point above at all click stops on the ring
If the iris action is not snappy, the lens iris mechanism is part of the problem and is likely the sole cause. Moving forward, lets make sure the shutter is OK:
  • Spot metering is a loose end in that use for general shooting is probably the largest cause of inappropriate exposure reported on this site. It probably is not a factor in the problem described on this thread, but might mimic the symptoms you are seeing. Turn it off unless taking readings with the intent to place exposure. Spot metering is inappropriate for general photography.
  • Avoid testing using auto-ISO or TAv modes. Small things like minimum and maximum range for ISO are often left out of trouble descriptions such that the shutter may be firing when the settings are dead wrong and not a reflection of the metering. This sort of thing is not always obvious in the EXIF.
  • For exposure issues, M mode is our best friend in that settings are settings stuff like auto-EV comp, shadow and highlight protection and such are not active
  • Don't use EV comp while testing unless essential to the test
To screen shutter function as a cause for your overexposure:
  • M mode
  • Set aperture to f/2.8 (wide open). In this setting, the stop-down mechanism and any issues with it are controlled for in regards to overexposure.
  • Set shutter speed to 1/800s, the setting at which there was overexposure in the example photo.
  • Set the ISO according to the meter reading and do a single test exposure to confirm a reasonable exposure. Use the camera's matrix metering. Do not use the spot meter.
  • Shoot a burst in continuous drive mode the same as before and scan for overexposed frames
If there are overexposed frames, either the light changed during the burst or the shutter timing is wrong or there is a mechanical issue with the shutter action or there is a serious issue with the image capture/processing pipeline.

There is one case that was not tested and that is a problem with aperture control by the body. It is relatively easy to check for underexposure traceable to aperture control, but somewhat difficult to test directly for inconsistent frame-to-frame stop-down. The closest we can do is to repeat the above test with the shutter at the same setting (1/800s) and the aperture set to f/10.0, the set aperture for the failed example photo. The assumption of course is that the shutter has tested good at that speed.

Well, there it is in detail. If there is no clear cause from direct examination or M mode evaluation, the answer may be a subtle issue of configuration or usage.


Steve

Last edited by stevebrot; 04-23-2019 at 09:49 PM.
04-24-2019, 07:43 AM   #18
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Steve, thanks for taking the time to think that all through - and articulate it so clearly. I understand, conceptually, what needs to be done.

I'm kind of jammed up today, but I'll mess with it this evening or early tomorrow and report results.
04-24-2019, 08:34 AM - 1 Like   #19
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QuoteOriginally posted by corvin Quote
I'm kind of jammed up today, but I'll mess with it this evening or early tomorrow and report results.
Cool! I can't help but wonder if this is related to the firmware update to 1.40. I know that sounds superstitious, but a new thread from yesterday regarding failed aperture control on a K-1/D FA* 50/1.4 makes me wonder if there might be a bug in the KAF4 support for that lens that might have spilled-over to aperture control in general. I would test except that I too, am still on 1.30.


Steve


Last edited by stevebrot; 04-24-2019 at 08:44 AM.
04-24-2019, 11:02 AM   #20
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Never had this problem with mine K3 ltd silver, wich is less than a year in my hands and now with fw. 1.4. And I abuse it a lot, plenty of shoots in cont H.

Is exposure linked with af point?
Check Custom menu pg 1 item 5.
Usually, I let this option turned off, in matrix meter and focus sel.
04-24-2019, 12:50 PM   #21
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QuoteOriginally posted by sungibr Quote
Is exposure linked with af point?
It is not obvious without downloading the examples and checking the EXIF, but the set exposure (aperture, shutter, ISO) is the same for both shots.


Steve
08-23-2019, 09:19 AM   #22
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First, apologies. I hate it when people ask for advice, get good advice, and don't return to the thread with the outcomes. I appreciate all of the input and diagnostic work.

Have had a rough summer and just getting to this again. It appears to me that it's only in two lenses. And both lenses have sticky blades. One is an older 300mm DA and the other is my 100mm 2.8 WR thing. I bought it from a third-party vendor, though, on Amazon in 2014 and don't think there's any chance of warranty. I love both lenses and would like to get them repaired. (I think leaving them in a hot car was the culprit???)

Again, thanks so much for the input here. And sorry about the bad diagnostic data I provided. Ugh.

Recommendations for a reliable place that might fix these lenses?
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