[mikesbike]

Well, it might not be the solenoid. By fortunate I really meant since LV was said to work fine, the thread went that the solenoid was probably NOT the problem, so that is fortunate. But any camera malfunctioning can be costly to repair. There is a DIY as to the solenoid, but any alternative issue is another story- maybe a DIY possible and maybe not.

---------- Post added 10-19-20 at 03:36 PM ----------

Once again, if the aperature control has failed, live view would not get proper exposures either, but the OP says live view is fine. Still points to the failure of the sensor located in the prism, which controls exposure only during viewfinder operation and not during live view, which is controled by the main sensor. Question for the OP, when set to full manual control, with ISO, aperature and shutter all set for proper exposure, is the picture still dark in viewfinder mode? Full manual control does not depend on any in camera metering, so should work in either viewfinder or live view. Try that and let us know your results.

Here is a plausible alternate theory. If the camera works in LV, just take a picture in good outdoor lighting- preferably a cloudless day, with the mode dial set to "P", and the exposure should be normal. Then there will also be a record of the shutter speed and aperture the camera has selected for that exposure, info available when reviewing the photo just taken. Then immediately, before the lighting can change, set the camera back to VF use, put the mode dial on "M" and manually set the same exposure parameters, and take a picture. If the exposure is good, and the camera works as it should, then the aperture solenoid is not the problem, and the above speculation is probably correct.

---

Last edited by mikesbike; 10-19-2020 at 03:43 PM.

[photogem]

No, that was not me who sent my camera for repair (not sure where that quote came from). Regardless, I'm not interested in trying to fix it myself. Thanks for the reply.

Just ask here in the forum if somebody would be able to repair it for you.
Ask in the appropriate forum:
Pentax K-30 & K-50 - PentaxForums.com
who knows, you might find somebody.
It's worth a try.

Well, and then you can try a repairshop I myself would normally not recommend:
Pentax Camera Repair - Aperture Control Repair
At least they seem to give longer warranty.

For US$ 100 + shipping the cheapest hope for somebody unable to apply DIY, which of course for some is just too scary...

Once again, if the aperature control has failed, live view would not get proper exposures either, but the OP says live view is fine.

Well, it might not be the solenoid. By fortunate I really meant since LV was said to work fine, the thread went that the solenoid was probably NOT the problem, so that is fortunate.

Those advices are wrong and totally misleading!
In my TUTORIAL for detection of aperture-block failure and in many other posts and discussions me and others made it very clear that LiveView often still works!

And I explained it in all detail why this is so but why one would get EXIF-Data which show the problem because in LV the lens closes to f4,0
if the solenoid is alright, but the aperture closes fully if the solenoid is stuck.
And yet, pictures often "seem*" fine. This is because for quite a while the solenoid gets some extra power because it actuates twice.
When the mirror goes down after the first actuation energy is freed (milli-amperes) which often release the stuck solenoid when you press the release button. (@Tracy68: This is technical stuff, but important because otherwise nonsense** gets spread in the internet!)


*seem, because metering is not 100% correct.
** nonsense in the sense of making no sense because based of lack of sense and lack of understanding of technical facts
i.e. not at all meant as an insult!

[photogem]

If the problem is with the diaphragm actuator, it would cause the same exposure problem in both viewfinder and live mode. It occures to me that in DSLR cameras there are two light metering sensors, one in the pentaprism housing that works when in view finder mode, reflected by the mirror, and in live view with the mirror up the main sensor itself determins the correct exposure. I'm thinking the sensor in the viewfinder is faulty, that's why the images are dark in that mode. You can check diaphragm operation by setting to manual, set shutter speed to one second and while looking into the lense you can watch the diaphragm close when you trigger the shutter. Try it with various f stop settings and observe for varied aperature operation. If the meter in the prism is faulty, I would think the camera should still expose properly in both live view and viewfinder mode if you use full manual mode providing the ISO, shutter and aperature are all set correctly. Something to try anyway.

This was the first post complete misleading:
Please read and understand:
Detection of aperture block/diaphragm-block failure/stuck solenoid K-30, K-50, K500 - PentaxForums.com
It would be good if those giving advice first study the problem.
By the way, what you name diaphragm-actuator is the solenoid and the problem is known since many years now.
Discussed in every detail.

[mikesbike]

Well then, if Maxman1947's theory is not plausible, simply disregard my post.

[photogem]

Well then, if Maxman1947's theory is not plausible, simply disregard my post.

It is not about being "not plausible" but being totally i.e. 100% wrong! And thus misleading not only the TO but others who will read such a thread!

The problem is that sometimes claims are made without having researched further.


We had the "dark-image-syndrome" now since about 2013/14 and it has been studied in all detail.
Giving others advice is very valuable because that is one of the reasons this forum is great and unique.
But one should know about the stuff one writes about.

For example you took on Maxman1947's claims and thus all the sudden we have wrong news about an issue which spread.

It is not about disregarding your post, quite the opposite!


Your post confirms Maxman1947's claim and thus strengthens something that should not be strengthened because it is 100% wrong:
LV does still work and what the TO describes for 99% certainty is the stuck solenoid and nothing else!

[mikesbike]

Perhaps I should have said "maybe so" in stronger terms. I meant in that spirit rather than backing up his claim. Simply dismissing his claim and the reasons why should be enough, which you did. I did not in any way dispute your response. If I did in any way mislead anyone, I apologize. There are numerous other alternate ideas given in this thread, and also experiences with exposure failure issues, other than the solenoid, apparently reported.

If shooting in manual mode will actually allow for the aperture to be set properly on one's own, using the camera's control of aperture as I outlined and not a lens aperture ring, with good exposure outcome yet the solenoid is nonetheless defective, then that was misleading and I do again apologize. If that is true, then one might possibly obtain a light meter for less than the $100 fix- which would just install another vulnerable solenoid. In this case, that could offer a workaround other than having to resort to lenses having an aperture ring to set aperture. And perhaps learn more about light meter reading and photography in the process.

---------- Post added 10-21-20 at 04:32 PM ----------

Given that you are not that fond of the camera, the most reasonable path might be to take the money that might have been applied towards a repair and use it to purchase something that is more to your liking.

My original and my main advice did and still does concur with Steve's. With the KP you get a much better camera in many ways. In addition to NOT being subject to the aperture solenoid failure, the body is of a much more durable build of pro-level quality, it has a superior set of controls, a pull-out screen for times when shooting from a high or low position, or when on a tripod set at a position far below eye-level, superior metering for more accurate exposures, much better higher ISO imaging for low light and/or action shooting, upgraded autofocus, and greater resolution for all around superior imaging. Great for JPEG images right out of the camera with its superior in-camera processing. And more features than I can think to list. All in a compact, easy to pack and easy to use design. The price these days is remarkable for a camera in this class.

[reh321]

Perhaps I should have said "maybe so" in stronger terms. I meant in that spirit rather than backing up his claim. Simply dismissing his claim and the reasons why should be enough, which you did. I did not in any way dispute your response. If I did in any way mislead anyone, I apologize. There are numerous other alternate ideas given in this thread, and also experiences with exposure failure issues, other than the solenoid, apparently reported.

If shooting in manual mode will actually allow for the aperture to be set properly on one's own, using the camera's control of aperture as I outlined and not a lens aperture ring, with good exposure outcome yet the solenoid is nonetheless defective, then that was misleading and I do again apologize. If that is true, then one might possibly obtain a light meter for less than the $100 fix- which would just install another vulnerable solenoid. In this case, that could offer a workaround other than having to resort to lenses having an aperture ring to set aperture. And perhaps learn more about light meter reading and photography in the process.

The basic issue is that this is not an 'exposure' issue.
The body's meter correctly computes exposure - the EXIF shows the correct exposure.

This is an "execution" issue.

If I use my DA 18-135mm lens on my K-30 in a situation that calls for an f/8 aperture, the EXIF will read "f/8". but the lens will deliver f/22 and the photo will be dark.
If I use my Sigma 10-20mm lens on my K-30 in a situation that calls for a f/8 aperture, the EXIF will read "f/8", but the lens will deliver f/32 and the photo will be darker if possible.

Using a lens where an aperture ring allows the lens to control the aperture works.

If I use my FA 28-105mm lens on my K-30 in a situation that calls for an f/8 aperture, I can set the aperture ring to "f/8", and the EXIF will not contain an f-stop but the photo will be fine.

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Last edited by reh321; 10-21-2020 at 05:05 PM.

[mikesbike]

The basic issue is that this is not an 'exposure' issue.
The body's meter correctly computes exposure - the EXIF shows the correct exposure.

This is an "execution" issue.

If I use my DA 18-135mm lens on my K-30 in a situation that calls for an f/8 aperture, the EXIF will read "f/8". but the lens will deliver f/22 and the photo will be dark.
If I use my Sigma 10-20mm lens on my K-30 in a situation that calls for a f/8 aperture, the EXIF will read "f/8", but the lens will deliver f/32 and the photo will be darker if possible.

Using a lens where an aperture ring allows the lens to control the aperture works.

If I use my FA 28-105mm lens on my K-30 in a situation that calls for an f/8 aperture, I can set the aperture ring to "f/8", and the EXIF will not contain an f-stop but the photo will be fine.

Yes, I get this, since it is the solenoid problem in this case. But I was referring here to others saying they've had faulty exposure problems from other causes.

So you are saying that if you have the solenoid problem, and you shot in manual mode, setting your aperture with the camera, not an aperture ring, the shot will turn out dark, indicating the cause being the typical solenoid issue. If this is true, my statement to the OP was not misleading.

---------- Post added 10-21-20 at 08:20 PM ----------

If I use my FA 28-105mm lens on my K-30 in a situation that calls for an f/8 aperture, I can set the aperture ring to "f/8", and the EXIF will not contain an f-stop but the photo will be fine.

Actually, that is not too bad then, since you can still use an AF lens and shoot with its aperture ring in the old way, but would miss out for other modes like Tv or fully automatic "P" or other AE modes where the camera sets the aperture.

[photogem]

The basic issue is that this is not an 'exposure' issue.
The body's meter correctly computes exposure - the EXIF shows the correct exposure.

This is an "execution" issue.

If I use my DA 18-135mm lens on my K-30 in a situation that calls for an f/8 aperture, the EXIF will read "f/8". but the lens will deliver f/22 and the photo will be dark.
If I use my Sigma 10-20mm lens on my K-30 in a situation that calls for a f/8 aperture, the EXIF will read "f/8", but the lens will deliver f/32 and the photo will be darker if possible.

This is as you describe it and of course also correct using lenses with an A-ring with pre-select aperture in M-Mode


But what EXIF can you read using LV if it still works with your K30?
I don't have any Pentax with stuck solenoid with me right now so I can't check and LV does not work always, possibly your K30 won't have it working either?

@mikesbike:
What was misleading was:

Well, it might not be the solenoid. By fortunate I really meant since LV was said to work fine, the thread went that the solenoid was probably NOT the problem, so that is fortunate.

because it strengthened the wrong claim of Maxman1947
The thread did NOT go towards "that the solenoid was probably NOT the problem" but the opposite.

I had answered about Maxman1949's wrong assumption/claim in my answer to reh321 in post #23

If I would have been able to I would have linked THIS THREAD much earlier but it was not possible then!

[reh321]

The basic issue is that this is not an 'exposure' issue.
The body's meter correctly computes exposure - the EXIF shows the correct exposure.

This is an "execution" issue.

If I use my DA 18-135mm lens on my K-30 in a situation that calls for an f/8 aperture, the EXIF will read "f/8". but the lens will deliver f/22 and the photo will be dark.
If I use my Sigma 10-20mm lens on my K-30 in a situation that calls for a f/8 aperture, the EXIF will read "f/8", but the lens will deliver f/32 and the photo will be darker if possible.

Using a lens where an aperture ring allows the lens to control the aperture works.

If I use my FA 28-105mm lens on my K-30 in a situation that calls for an f/8 aperture, I can set the aperture ring to "f/8", and the EXIF will not contain an f-stop but the photo will be fine.

It was cloudy/fogish this morning, but I took two photos to illustrate the issue.

I ran both photos through gimp {to generate a histogram - I didn't actually change anything}, which seems to mess up the EXIF some, but in both photos, I had my K-30 set to 'Av' mode, ISO=800.

The first photo had f-stop of f/8, which gave shutter speed = 1/45. The body's f-stop control actually delivered f/32, so the histogram was scrunched over to the left.

The second photo had f-stop of f/22, which gave shutter speed = 1/6. The body's f-stop control actually delivered f/32, so the histogram was the left 1/2 of the graph.

[reh321]

But what EXIF can you read using LV if it still works with your K30?
I don't have any Pentax with stuck solenoid with me right now so I can't check and LV does not work always, possibly your K30 won't have it working either?

After reading your post, I tried the first photo again {the F/8 one} using LV.
This time, my camera was reporting a shutter speed of 1 second, so I sat the camera on our deck rail;
on the LCD, the building was flashing, to show it was "blown", but the histogram doesn't show that at all - really confusing!

[photogem]

It was cloudy/fogish this morning, but I took two photos to illustrate the issue.

I ran both photos through gimp {to generate a histogram - I didn't actually change anything}, which seems to mess up the EXIF some, but in both photos, I had my K-30 set to 'Av' mode, ISO=800.

The first photo had f-stop of f/8, which gave shutter speed = 1/45. The body's f-stop control actually delivered f/32, so the histogram was scrunched over to the left.

The second photo had f-stop of f/22, which gave shutter speed = 1/6. The body's f-stop control actually delivered f/32, so the histogram was the left 1/2 of the graph.

f-stop f/22 is too close to the lens you used being fully stopped down!
Depending what the max aperture of a lens is, i.e. f22 or f32, the actuation of the solenoid is not important, i.e. if stuck, the camera meters anyway f22 or f32
and thus the picture is fine, which I described here in detail:
Detection of aperture block/diaphragm-block failure/stuck solenoid K-30, K-50, K500 - PentaxForums.com

The best would be photos wide open or lets say f4 or f5,6!

[mikesbike]

What was misleading was:
Originally posted by mikesbike*
Well, it might not be the solenoid. By fortunate I really meant since LV was said to work fine, the thread went that the solenoid was probably NOT the problem, so that is fortunate.
because it strengthened the wrong claim of Maxman1947
The thread did NOT go towards "that the solenoid was probab

Well, this is taking things out of context, making too much of it. and if read no further would be misleading. My goal was not to specifically "take sides". The gist of what I was getting at was as follows-

What I was trying to say, putting myself in that position, and likewise not having experience in this matter, was some of those responding saying one thing- which maybe so, maybe not, while others say differently- maybe so and maybe not- what to believe. Then as to actual advice I gave, was to address the reality of the situation, there being a simple test which the intention of my post was to give and did give. As a solution, it would clarify the matter- the faulty aperture solenoid or something else. Then with your very convincing subsequent posts, I thought- why mention the simple test yet again. The test may just be a waste of time.

---------- Post added 10-23-20 at 08:19 PM ----------

I had my K-30 set to 'Av' mode, ISO=800.

The only way I have ever used an aperture ring on a DSLR is when using an old MF lens having no "A" position, then shooting in "M" mode and with the green button to set shutter speed. So my question is, if using an AF lens or another having the "A" position, and using the Av mode instead, activating the "Use Aperture Ring" feature and setting the aperture via the lens ring, does the Av mode setting still engage the camera's (defective) aperture control- or does it disconnect from that and revert to the lens ring setting? In other words, can I then use Av instead of the M setting?

[photogem]

As a solution, it would clarify the matter- the faulty aperture solenoid or something else. Then with your very convincing subsequent posts, I thought- why mention the simple test yet again. The test may just be a waste of time.

The test is crucial, because it gives right away an answer: Either the solenoid is stuck or it works.
The test does exactly that and then one knows.
And in 99% of all dark image problems with a Pentax DSLR since the K30 and using a solenoid this is the very culprit.

[m42man]

The only way I have ever used an aperture ring on a DSLR is when using an old MF lens having no "A" position, then shooting in "M" mode and with the green button to set shutter speed. So my question is, if using an AF lens or another having the "A" position, and using the Av mode instead, activating the "Use Aperture Ring" feature and setting the aperture via the lens ring, does the Av mode setting still engage the camera's (defective) aperture control- or does it disconnect from that and revert to the lens ring setting? In other words, can I then use Av instead of the M setting?

A strange quirk seems to be that, with an afflicted K-50, you can set Av mode, with Aperture Ring Enabled, and the camera will stop the lens down to the aperture set by the aperture-ring when the shutter is fired. This is not the behaviour you get with a healthy camera.

This is very handy, but as far as metering is concerned, the camera has no knowledge of the set aperture, so assumes the same aperture as when metering was done - i.e., wide-open. So, in order to get the correct exposure, you need to use exposure compensation. For example, if you're using an f2 lens set to f4, you need to set +2EV compensation. Works a treat, and exposure is accurate, as this apes normal operation (unlike stopped-down metering with the green button).