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Forum: Pentax K-30 & K-50
07-04-2021, 11:13 AM
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The replacement solenoid arrived yesterday, and I fitted it today. I got it from the seller that photogem recommended -- his listing shows up on ebay uk as well. The surgery went well and the K50 is back in working order. The soldering is a bit of a trial! Many thanks to photogem for his advice and extensive documentation on exactly how to do the operation.
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Forum: Pentax K-30 & K-50
06-05-2021, 09:46 AM
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Can you explain the exact role of the aperture solenoid? The solenoid seems to be a purely on/off device, but the camera is able to set the aperture to many different settings. What accomplishes that?
Anyway, I've watched a bunch of Youtube videos on getting at the solenoid, and your articles on on the whole history of this, and why filing the moving part isn't a good idea, and why only the "white" solenoid is good enough. There are people selling the white solenoid on eBay (or at least claiming to, eBay being eBay), so hopefully I'll be able to fix this at some point.
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Forum: Pentax K-30 & K-50
06-04-2021, 01:53 AM
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Thanks for that link to tests for ABF.
By the first test (take a picture using the viewfinder in AV mode with the widest and the narrowest aperture), the wide setting gives an underexposed image and the narrowest gives a correctly exposed one. Looks like ("99.9%") the solenoid is stuck and needs to be replaced.
But by the second test (look into the lens while switching Live View on and off), I'm not sure how to interpret the result. The aperture does switch between closed and open, but it is at maximum in viewfinder view and minimum in live view. This is so independently of the F stop selected on the camera (in Av mode).
So the diaphragm is being operated, but only at two settings, maximum and minimum.
As for the use of an aperture ring, the camera is already set to allow this ("Using Aperture Ring" -> Enable). It takes pictures whether the ring is on "A" or any manual setting. I had assumed that the reason the camera shows "F--" when aperture is set on the aperture ring is that my lenses with aperture rings aren't modern enough to communicate their setting to the camera. The K-50 and the lens that came with it (no ap ring) are 15 years old, and my Ricoh 28-85mm lens (with ring) at least ten years older than that.
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Forum: Pentax K-30 & K-50
06-01-2021, 11:19 AM
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I'm having a problem with my Pentax K-50 that I've seen several earlier threads on, but the symptoms are not quite the same. Pictures taken through the viewfinder are very underexposed, while in live view they are normal. According to earlier threads, it looks very much like the aperture control solenoid not working, especially as in manual mode the pictures I get are independent of the aperture setting. I tried the trick of assigning Optical Preview to the RAW/Fx button and clicking it a lot to exercise the mechanical parts. On the widest aperture setting, nothing happens when I press the button (as I would expect), but on all other aperture settings, pressing the button stops it right down. This looks more like a problem in how the camera is controlling the aperture than a simple failure of the solenoid.
There is a further complication. If I fit a lens with its own aperture ring and set the aperture there, there is still a problem. The camera shows the F number as F--, so it knows that aperture adjustment is not available. The aperture mechanism shouldn't then be an issue. But the same thing still happens. In automatic mode, if I switch between viewfinder and live view, then even without taking a picture I can see the exposure and ISO settings changing between the two. If I rotate the aperture ring in live view mode, I can see the ISO changing to compensate. In viewfinder mode, the ISO and exposure time remain fixed.
This happens whether the metering mode is set to multi-segment, center-weighted, or spot.
I have updated the camera firmware (from 1.00 to 1.10) but nothing changed.
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