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Forum: Troubleshooting and Beginner Help
10-27-2014, 07:56 PM
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The body seems to know the range of apertures that should be allowed, and altering the focal length seems to correctly update the effective aperture that's displayed on the LCD display. So based on that, I was assuming that the contacts and associated electronics were ok. Is that a safe assumption to make?
Also, regarding the bent aperture level: Visually, it looks ok, but based on the fact that the aperture is in a normally fully-open state when not in use, and the body only stops it down during a shot, I assumed that mechanism is not at fault.
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Forum: Troubleshooting and Beginner Help
10-27-2014, 05:40 PM
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I haven't been able to try any other lenses unfortunately. As Na Horuk says, it should be cheap to find a similar replacement, so maybe I'll try that.
What makes you think it could be the lens (or the contacts)? The body is evidently capable of manipulating the aperture - it just doesn't seem capable of manipulating it correctly.
Is the lens responsible for reporting the position of the aperture back to the body? Could that feedback mechanism be an issue?
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Forum: Troubleshooting and Beginner Help
10-27-2014, 04:32 PM
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Thank you both for the input.
The lens and body are well beyond warranty support unfortunately!
Steve, I tried the test you described, and can confirm that the aperture does not stay fully open.
It makes me think that although the hardware is functional (the body can still manipulate the aperture), the software has become corrupt because it's not controlling the actuator correctly? Or perhaps the actuator is just not sensing it's own position properly, and could do with a clean?
I'll try some more poking around.
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Forum: Troubleshooting and Beginner Help
10-27-2014, 02:52 AM
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Hello!
I have a Pentax K-r, and a while ago, I found that the metering would often be way off; perhaps -5 stops? I'm using the stock 18-55mm lens that came with the body.
I'm almost always shooting in aperture priority, and after a lot of experimenting, I eventually got to the root of the problem.
I discovered that if I was shooting at the smallest aperture, the metering would be ok, but it was when I opened the aperture up, the metering went crazy and my pictures would be massively underexposed.
Ultimately, the problem was this: when I selected f/40, I could see the aperture narrow right down to a pinhole as expected, but when I selected ~f/4.0... the aperture would narrow right down to a pinhole!! Whatever aperture I select; the shots get taken at f/40.
I've just updated to the latest firmware (the one I was running was horribly out of date), but the problem persists. Has anyone experienced this problem before and found a solution?
I don't know if this is related, but around the same time this problem started, I was trying out some old K mount lenses from a much older Pentax.
Thanks for any advice.
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