[reh321]

There's an odd quirk about failing K-30/50/500: they stop the aperture down in Av mode. Not only do you not need to use the green button, but you get more accurate exposures. (I'm talking about K-mount lenses with aperture rings.)

This is not an "odd quirk".
The aperture is always opened as wide as it can go for framing and focusing, then "shuts down" to the set value when you actually take the picture.
When you set the aperture using the body, the solenoid is part of the mechanism which stops shutting down at the value set - so a bad solenoid will allow the aperture to go all the way to the narrowest value.
When you set the aperture using an aperture ring, the lens will stop the shutting down at the value set - the solenoid has no responsibility.
So the aperture will be set correctly in both 'M' and 'Av' modes when the aperture is set at the lens.

I still use my K-30 in both 'M' and 'Av' modes, just as I used my "ME/SE" - which never did have a means of controlling the aperture.

[i_trax]

My K-30 "died" recently with the same common problem.
I looked around and there are so many K-50 available to purchase on the used market really cheap.
I love AA batteries.

I bought one in perfect working order with ~ 5k clicks on the shatter and kept K-30 as is to be used with M42 lenses.
The K-50 costs me less than replacement white solenoid.
Something perhaps to consider.....

[m42man]

This is not an "odd quirk".
The aperture is always opened as wide as it can go for framing and focusing, then "shuts down" to the set value when you actually take the picture.
When you set the aperture using the body, the solenoid is part of the mechanism which stops shutting down at the value set - so a bad solenoid will allow the aperture to go all the way to the narrowest value.
When you set the aperture using an aperture ring, the lens will stop the shutting down at the value set - the solenoid has no responsibility.
So the aperture will be set correctly in both 'M' and 'Av' modes when the aperture is set at the lens.

I still use my K-30 in both 'M' and 'Av' modes, just as I used my "ME/SE" - which never did have a means of controlling the aperture.

I'm afraid you're wrong. In Av mode, a healthy Pentax dSLR will not stop a K-mount lens which has an aperture ring down at all, unless the aperture ring is set to "A" (if it has that position). That's because the camera has no knowledge of the set aperture. When you use such a lens in Av mode, you will get a correctly exposed photo, but it will have been taken with a wide-open aperture, regardless of aperture setting.

The quirk is that a camera suffering from "aperture block failure" will stop the lens down, and you need to take steps, using exposure compensation, to get the correct exposure.

---------- Post added 06-28-2021 at 05:54 PM ----------

My K-30 "died" recently with the same common problem.
I looked around and there are so many K-50 available to purchase on the used market really cheap.
I love AA batteries.

I bought one in perfect working order with ~ 5k clicks on the shatter and kept K-30 as is to be used with M42 lenses.
The K-50 costs me less than replacement white solenoid.
Something perhaps to consider.....

Do not bank on the K-50 being immune to aperture block failure - shutter count is a bad indicator of solenoid health. In fact, we think that lack of use may exacerbate the problem.

Actually, the fact that it's OK after such little use may be a good sign! Whatever, good luck with the K-50, and at least you seem to have suitable lenses should the gremlins creep in...

[i_trax]

I'm afraid you're wrong. In Av mode, a healthy Pentax dSLR will not stop a K-mount lens which has an aperture ring down at all, unless the aperture ring is set to "A" (if it has that position). That's because the camera has no knowledge of the set aperture. When you use such a lens in Av mode, you will get a correctly exposed photo, but it will have been taken with a wide-open aperture.

The quirk is that a camera suffering from "aperture block failure" will stop the lens down, and you need to take steps, using exposure compensation, to get the correct exposure.

---------- Post added 06-28-2021 at 05:54 PM ----------



Do not bank on the K-50 being immune to aperture block failure - shutter count is a bad indicator of solenoid health. In fact, we think that lack of use may exacerbate the problem.

Actually, the fact that it's OK after such little use may be a good sign! Whatever, good luck with the K-50, and at least you seem to have suitable lenses should the gremlins creep in...

[m42man]

Good good! Yes, forgot about them - they use a completely different means of controlling aperture, so they will work just fine (as long as the K-50 has up to date firmware, also the K-30 if it has been updated to the right K-50 firmware).

[i_trax]

Good good! Yes, forgot about them - they use a completely different means of controlling aperture, so they will work just fine (as long as the K-50 has up to date firmware, also the K-30 if it has been updated to the right K-50 firmware).

yes , my K-30 is properly hacked

[micl161]

I'm sorry, but the photo is not taken with a "wide-open aperture".
The aperture opening is stopped by the lens.
I just checked my K-30, which has not had working body-control of the aperture for over two years, and when I set the ring to f/8, the aperture did shut down from wide-open to something which must be f/8; then I did the same experiment with my KP which has a completely different sort of mechanism but functions the same.
It is true that a "M42" lens will not shut down - because it is already at the specified aperture.

I will not discuss this further - you will believe whatever you will believe.

Originally posted by m42man I'm afraid you're wrong. In Av mode, a healthy Pentax dSLR will not stop a K-mount lens which has an aperture ring down at all, unless the aperture ring is set to "A" (if it has that position). That's because the camera has no knowledge of the set aperture. When you use such a lens in Av mode, you will get a correctly exposed photo, but it will have been taken with a wide-open aperture, regardless of aperture setting.


I think this is not talking about a aperture issue (K30) camera its talking about a HEALTHY camera.
I just test with my K5 (no aperture issue) and confirm what m42man said.

[photogem]

I'm afraid you're wrong. In Av mode, a healthy Pentax dSLR will not stop a K-mount lens which has an aperture ring down at all, unless the aperture ring is set to "A" (if it has that position). That's because the camera has no knowledge of the set aperture. When you use such a lens in Av mode, you will get a correctly exposed photo, but it will have been taken with a wide-open aperture, regardless of aperture setting.

The quirk is that a camera suffering from "aperture block failure" will stop the lens down, and you need to take steps, using exposure compensation, to get the correct exposure.

I think this is the problem which @re321 correctly questioned:

With a stuck solenoid and set to Av-Mode and the lens on A-position the camera will NOT STOP DOWN THE LENS!


The solenoid is stuck and the lens will remain closed completly, lets say f22 or f32 depending on which lens you use.
That is something different than a lens stopping down to lets say f5,6!

Using the body like that in Av-Mode when it cannot meter correctly but using EV compensation possibly works (I have never tried it and I don't have a body here with stuck solenoid, but I will test it next time when I have one here) but it should be different for different lenses.
I don't see any reason why one should get more accurate exposures?

The solenoid being closed and lets say f32 would be fully closed aperture then Av-Mode + EV compensation will force the Pentax to chose very long exposure time.

@re321 could find out because his K30 has a stuck solenoid.

[m42man]

I'm sorry, but the photo is not taken with a "wide-open aperture".
The aperture opening is stopped by the lens.
I just checked my K-30, which has not had working body-control of the aperture for over two years, and when I set the ring to f/8, the aperture did shut down from wide-open to something which must be f/8; then I did the same experiment with my KP which has a completely different sort of mechanism but functions the same.
It is true that a "M42" lens will not shut down - because it is already at the specified aperture.

I will not discuss this further - you will believe whatever you will believe.

Why can't you read my post? It's straightforward enough - I don't understand how you could get it wrong. It says:

" In Av mode, a healthy Pentax dSLR will not stop a K-mount lens which has an aperture ring down at all, unless the aperture ring is set to "A" (if it has that position)."

Note the word "healthy".

You are talking about a K-30 with aperture block failure, about which I said:

"The quirk is that a camera suffering from "aperture block failure" will stop the lens down, and you need to take steps, using exposure compensation, to get the correct exposure."

So you just confirmed what I said. And I was very specific in talking purely about K-mount lenses - not M42.

I'm very happy not to continue this ridiculous conversation.

---------- Post added 07-03-2021 at 05:11 PM ----------

I think this is the problem which @re321 correctly questioned:

With a stuck solenoid and set to Av-Mode the camera will NOT STOP DOWN THE LENS!


The solenoid is stuck and the lens will remain closed completly, lets say f22 or f32 depending on which lens you use.
That is something different than a lens stopping down to lets say f5,6!

I'm surprised at you, Photogem. Please re-read what I wrote. I'm talking about K-mount lenses with aperture rings. An afflicted camera will stop the lens down to the aperture defined by the aperture ring. Only a lens without an aperture ring will have no way of preventing it from stopping all the way down to f32.

Using the body like that in Av-Mode when it cannot meter correctly but using EV compensation possibly works (I have never tried it and I don't have a body here with stuck solenoid, but I will test it next time when I have one here) but it should be different for different lenses.
I don't see any reason why one should get more accurate exposures?

It doesn't "possibly work". It just works. And it gets more accurate exposures because you are emulating what happens within the camera, normally - i.e. metering wide-open and calculating the exposure required for the set aperture. Stop-down metering is known (arguably) to produce inconsistent exposure outcomes (and it's not really a "normal" way of taking a shot).

---------- Post added 07-03-2021 at 05:19 PM ----------

And thanks for your support, micl161.

(There's usually someone who bothers to read my posts properly without jumping to incorrect conclusions...)

[photogem]

I did read your posts concerning this issue very carefully.
Sometimes I still come across difficulties because English is not my native language and I hardly communicate by speech but 99% of it is by reading or writing.

But as I wrote before: I don't have any K30/50/500 or other here with stuck solenoid so I cannot test it.
I also wrote that as soon as I shall have one I will do the tests and suggested to @re321 that he could do the test as he has a K30 with a defunct solenoid.
Should be easy for him as he has many lenses and if I recall correctly some with A-rings.

[photogem]

So, to bring this to a final end because I have a Pentax with stuck solenoid right here, it's a K-S1, but it does not matter, the principal how the solenoid works
is exaclty the same as with the K30 or K50.

@m42man is correct!

I have right now 2 x K-S1's
and the K-S1 with the stuck solenoid behaves exactly as @m42man described with the K50 and a stuck solenoid.

Both K-S1's of course have the menu accordingly so lenses with an A-ring can be used for preselected aperture.
Lenses I used:
FA50/1,4
F50/1,7
A50/2,8 macro and all of them behaved the same way... to my surprise not only in Av-mode but as well in Tv, Tav, etc.
But only on the K-S1 with stuck solenoid!

1. K-S1 fully functioning (repaired long time ago with the Japan-Solenoid):
If the aperture on the A-ring is set to any other value than A it will not stop down but stays wide open!

2. K-S1 w. stuck solenoid:
If the aperture on the A-ring is set to any other value than A it will stop down exactly to the chose value, i.e. such as f1,7, f2,8, f4, f5,6, f11, f22 on the F50/1,7
And it behaves the same way in Tv, Tav and other modes.

@reh321: I am surprised you didn't take on that offer to do the tests on your K30?
You had the chance and you were the person writing:

I'm sorry, but the photo is not taken with a "wide-open aperture".
The aperture opening is stopped by the lens.
I just checked my K-30, which has not had working body-control of the aperture for over two years, and when I set the ring to f/8, the aperture did shut down from wide-open to something which must be f/8; then I did the same experiment with my KP which has a completely different sort of mechanism but functions the same.
It is true that a "M42" lens will not shut down - because it is already at the specified aperture.

I will not discuss this further - you will believe whatever you will believe.

You changed your original posting but it had been quoted so it was there anyway.
Why not admit to it that you where wrong?

[m42man]

Hi again Photogem.

Yes - the mechanism is pretty clear:

The camera will always release the lens's aperture stop-down lever when it takes a shot. And it always uses the solenoid and its associated mechanisms to control the extent to which the lever can move - zero movement equating to no stop-down.

In Av mode, with Enable Aperture Ring set, it always instructs the solenoid to set the lens to wide-open, i.e. to inhibit any movement of the lever, and to take the shot with a wide-open lens. It does this because it has no knowledge of the intended aperture, so would not be able to calculate correct exposure. So at least you end up with a correctly exposed shot.

If the solenoid is faulty, release of the aperture lever is unconstrained, and the lens will therefore always stop down as much as it can. If the lens has an aperture ring set to a specific aperture, that determines the extent to which the stopping-down occurs. So the taking aperture is that which has been defined by the aperture ring.

Since the camera has already determined the correct exposure assuming a wide-open lens, the user has to do the calculation for the set aperture, and control the exposure via the Exposure Compensation facility.

[Mushu]

Sorry to necro this post, but to stay on topic, I'm thinking of just buying the new K-1 Mk II and wondering if it also suffers from a dying aperture solenoid before I plunk down $two grand? Was thinking about repairing my K-30 but not sure about it now that I've read on how many different sized screws there are and how everything must be put back together exactly the same, I'm sure I would sneeze or something and get everything messed up. My old K1000 still does everything it's supposed to lol... :-(

[i_trax]

K-5 , K-3 and K-1 series + KP are OK , very different mechanism

[photogem]

Sorry to necro this post, but to stay on topic, I'm thinking of just buying the new K-1 Mk II and wondering if it also suffers from a dying aperture solenoid before I plunk down $two grand?

As @i-trax already wrote, no solenoid in the modern semi- and prof. Pentaxbodies (K10D and K20D were the last semi's to have it but never failed).

If you plan to buy a K-1II, I wouldn't compare it to the K-30. If then to the K3III (which also doesn't use a solenoid).
I haven't purchased a K-1 because I would have to buy more lenses.