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04-24-2022, 01:04 PM   #106
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QuoteOriginally posted by S_Miller Quote
Is this just my bad luck? Or do all camera manufacturers have the same issues with quality?
Anyhow, appreciate the forum and a chance to vent a bit, but don't take too seriously the anecdotes you hear. I suspect the failure rate is far higher than understood here. This will be my second failed camera (the other was a KP, but that only cost a few $00). For me, I'm experiencing a 66% failure rate on camera bodies, probably around the 2-3 year old mark.
For awhile I was a Canon user. That ended when I had two Rebels in a row die after having processor problems.
The Rebels ended up in the county dump - there is no alternative way of dealing with processor issues.
The K-30 which came next experienced “Dark Image Syndrome”, but I still use it with old film lenses that allow me to set aperture at the lens.
Later I did purchase a KP, but the K-30 could still serve as my primary camera.

04-25-2022, 04:59 AM   #107
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QuoteOriginally posted by swanlefitte Quote
Pretty sure all camera fail eventually. A 2% per year is more likely. I think cameras are designed to last an expected 4 years these days.
I had a canon xl1s camera back in 2005 that took 6 months to repair. It was about a year old.

If you use a plm lens or a manual one, it doesn't exercise the solenoid. Mine failed using it every day when I only used the 55-300 plm for a few months.
The lens type "plm" or "manual" doesn't matter it is the shutter that fails and it is in the camera body that actuates the shutter & the aperture, which is the way I understand it.
04-25-2022, 08:07 AM   #108
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QuoteOriginally posted by SharkyCA Quote
The lens type "plm" or "manual" doesn't matter it is the shutter that fails and it is in the camera body that actuates the shutter & the aperture, which is the way I understand it.
The shutter doesn't fail at all. The aperture fails to be open when the shutter works. This is because the solenoid won't open.

The PLM can still be used with this problem because it doesn't use the aperture block. Consequently, using this lens doesn't exercise the solenoid. It is the same as letting the camera sit.
04-25-2022, 09:34 AM   #109
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QuoteOriginally posted by SharkyCA Quote
The lens type "plm" or "manual" doesn't matter it is the shutter that fails and it is in the camera body that actuates the shutter & the aperture, which is the way I understand it.
Exactly what are you talking about?
Yes, the camera body can control the aperture, but in the K-70, a solenoid is involved in that control, and that is the part which typically fails when a K-70 suffers from “Dark image Syndrome”. With a KAF4 lens {which typically includes “PLM lenses”}, or a lens which allows the user to ‘manually’ control the aperture via an aperture ring, the solenoid is not involved in controlling the aperture, and “Dark Image Syndrome” is not an issue. In any case, Dark Image Syndrome” involves pushing the histogram way to the left; the shutter does work - a photo is taken - but it looks dark to the user because the photo uses only the ‘dark’ part of a histogram.


Last edited by reh321; 04-25-2022 at 09:55 AM.
04-25-2022, 11:39 AM   #110
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QuoteOriginally posted by SharkyCA Quote
The lens type "plm" or "manual" doesn't matter it is the shutter that fails and it is in the camera body that actuates the shutter & the aperture, which is the way I understand it.
Here there are two misunderstandings:
1. PLM is only the motor, it is KAF4 which matters if one wants to use a Pentax with ABF with all modes. KAF4 lenses don't use the solenoid.
2. As others said, the solenoid controls the aperture of the lens but not the shutter.
The shutter is opened and closed by 2 extra strong solenoids though. Maybe this lead to the misunderstanding?

So 3 parts which must go exactly syncronious together:
1. Shutter: 2 strong solenoids, different to:

2. Aperture: 1 solenoid

3 Mirror up: motor
04-25-2022, 12:32 PM   #111
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The solenoid may not be directly involved in closing the iris on a Kaf4 but does it still actuate or not? Kaf4 lenses lack a the aperture actuating lever so it wouldn't matter if the actuator on the camera side moves or not. With lens with aperture rings it would have to move to allow the lens to stop down. Adapted M42 lens do not need the actuator either. I suppose one could leave the M42 lens off and see what the actuator does when you release the shutter.
04-25-2022, 02:17 PM   #112
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QuoteOriginally posted by Not a Number Quote
The solenoid may not be directly involved in closing the iris on a Kaf4 but does it still actuate or not? Kaf4 lenses lack a the aperture actuating lever so it wouldn't matter if the actuator on the camera side moves or not. With lens with aperture rings it would have to move to allow the lens to stop down. Adapted M42 lens do not need the actuator either. I suppose one could leave the M42 lens off and see what the actuator does when you release the shutter.
An interesting question. I have to wait until I repair another Pentax with KAF4 ability and solenoid plus my DA55-300PLM and check it when open to know for sure.

With a M42 lens the solenoid doesn't actuate, that I have tested.

04-25-2022, 02:49 PM   #113
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QuoteOriginally posted by Not a Number Quote
The solenoid may not be directly involved in closing the iris on a Kaf4 but does it still actuate or not? Kaf4 lenses lack a the aperture actuating lever so it wouldn't matter if the actuator on the camera side moves or not. With lens with aperture rings it would have to move to allow the lens to stop down. Adapted M42 lens do not need the actuator either. I suppose one could leave the M42 lens off and see what the actuator does when you release the shutter.
The solenoid does not move the lever - it stops the lever at the right point, something done by the lens itself if I have set a value with the aperture ring.

My K-30 has lost that ability, so the aperture goes to fully shut down with a DA lens, while my FA stops the movement itself if the aperture ring is set to a particular value.

The camera body knows what kind of lens is mounted, so I believe it provides only the functionality needed.
04-25-2022, 07:37 PM   #114
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You're right the actuator does not move the lever, the spring on the lever does. How ever the lever can't move unless the actuator does.

BTW: The actuator moves on the K10D when no lens is attached. The K10D uses the solenoid based control block.

So if the actuator still moves with a Kaf[sub]4[/4], aperture ring enabled or screwmount lens how is it not getting "exercised"?


Last edited by Not a Number; 04-25-2022 at 08:17 PM.
04-25-2022, 08:29 PM   #115
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I'm aware that the lever moves, but if you would have your K100D open, you'd see that the solenoid doesn't move.
That I had tested long time ago:

The white wheel in the middle moves as does the one on the right. But the solenoid stays quiet.

One cannot see the difference from the outside without having the body open.

How it is with a KAF4 cabable body if a KAF4 lens is attached I have yet to find out.
04-26-2022, 04:02 AM   #116
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QuoteOriginally posted by Not a Number Quote
So if the actuator still moves with a Kaf[sub]4[/4], aperture ring enabled or screwmount lens how is it not getting "exercised"?
The solenoid stops actuator motion.
There are other things - such as hitting the end - which can stop actuator motion.
So actuator motion does not imply solenoid activity.
It is a mathematical fallacy to say a=>b means that b=>a.
When photogem is able to look inside, he will report whether there is any solenoid activity.
04-27-2022, 12:30 AM   #117
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Well, might take some time: My next Pentax to repair is a K-S1 which cannot serve to observe the solenoid, one has to attach the front with top to test it, so the solenoid is fully covered.
Might take some time, K30's or 50's show up less these days to be repaired.
Mostly K-S1's and few K-S2's
04-27-2022, 06:26 AM   #118
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A k50 needed the software update to use kaf4. Someone who can read the script might be able to say how it changes the operation.

I am curious to know for sure.
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