K-50, Aperture Ring and Av Mode

**K2 to K50** · 09-08-2019, 11:45 PM

Originally posted by pschlute

Not quite. Changing the aperture using the ring on a K-mount lens will not stop the lens down. The lens is stopped down during capture. This enables open aperture focussing. But the mounts used on a modern DSLR are such that the stop-down will only take place in M or B or X mode. In Av mode (and any other auto mode) the lens will not be stopped down at capture.
.........
ps. M42 lenses behave differently

OK, seems I have been misunderstanding how the M lenses work on my K50 or KP. This forum continues to be an education!

stevebrot · 09-09-2019, 04:48 PM

Originally posted by m42man

So, if you're unlucky enough to get aperture block failure, you get the benefit of an arguably superior option when using a legacy lens.

Except that you have to remember to set exposure compensation to match the aperture ring setting and even then the metering might not be right. I don't know that this is better than simply using M mode on a properly functioning camera.

Steve

m42man · 09-10-2019, 02:30 AM

Originally posted by stevebrot

Except that you have to remember to set exposure compensation to match the aperture ring setting and even then the metering might not be right. I don't know that this is better than simply using M mode on a properly functioning camera.

Steve

Well, equally, you can set an aperture (perhaps to maximise sharpness) and then shoot away without needing to remember to use the green button before each shot (assuming lighting is varying).

But why do you say the metering might not be right? Metering is carried out wide open, just like a normal camera, and the appropriate shutter speed set according to the chosen shooting aperture, just like a normal camera. Exposure compensation is effectively just the same as the camera actually knowing the (relative) aperture (whether for a vintage SLR via a non-crippled K-mount linkage, or by the user selecting an aperture using a thumbwheel).

So you'd expect the same exposure accuracy as you get for a lens in normal use.

Stop-down metering sounds like it would be immune to exposure errors due to the actual aperture being inaccurately implemented by the lens, but in my experience this seems to be outweighed by errors presumably induced by the metering system coping badly with varying apertures.

Anyway, it's nice to have the choice. I'd suggest users try both methods and compare results for themselves.

**photogem** · 09-13-2019, 10:53 AM

Originally posted by Adam

All Pentax cameras should behave this way AFAIK- you just need to allow the use of the aperture ring through the menu.

I was curious about it but wanted to wait until I had a Pentax with a stuck solenoid in my house.

Today a K-50 arrived, typical symptons.

I tried it the way member m42man suggested (lens: F50/1,7) and came to the same conclusions!
It works exactly the way he described.

Then I took an already repaired K-30, set it on AV but the lens not on A but a chose aperture:
Opposite you thought it did not work (wait, more will come!)

It would not fire when I changed the A-ring to any other position than A.

As soon as I press the the release button, the display goes off, as if there would be some kind of shortage and the K30 would not fire.
Back on A and all is fine.

So I tried it with the K5II and suprise: It works the same way as the K-30 with the stuck solenoid!

I then opened the K-50 for repair but then placed the battery back in and then the F50/1,7:
The solenoid does not actuate at all.

Then I exchanged the solenoid (white solenoid): All was working as usual and as it should.

I then tested it again in AV mode but the lens not on A but a chosen aperture and very strangly it works .. and yet, the solenoid does not actuate!

So I have no explanation at all but have to wait until further K30's or similar arrive here and I can test.

Last edited by photogem; 09-14-2019 at 03:34 AM.

stevebrot · 09-13-2019, 12:28 PM

Originally posted by photogem

So I tried it with the K5II and suprise: It works the same way as the K-30 with the stuck solenoid!

The behavior of the K-30 with the stuck solenoid makes sense, assuming the camera treats all non-A lenses as "wide open" in all auto-exposure modes. A K-5II behaving the same way is completely unexpected unless the camera is broken. No stop-down with a non-A lens has been the norm in other than M, X, and B modes with crippled mount cameras pretty much forever.*

Steve

* All dSLRs. I don't know about the crippled mount film cameras.

**photogem** · 09-14-2019, 03:42 AM

Originally posted by stevebrot

The behavior of the K-30 with the stuck solenoid makes sense, assuming the camera treats all non-A lenses as "wide open" in all auto-exposure modes. A K-5II behaving the same way is completely unexpected unless the camera is broken.

The K5II is in best order. So are my KP and K3II:

Which means I tested this on those as well, they behave all like the K5II and thus work in AV-mode with an A-Lens preset on a chose aperture.

I then tested it on another K50 as well as on a K500 and another K30 (those are around in the family because I repaired quite a few):

With a stuck solenoid all behave the same and can be used this limited way in AV-mode.
The solenoid does not actuate if an A-lens is not on A but on a chose aperture

But as soon as the solenoid is alright again, we have two different results:

- The K50/K500 work in AV-mode with chosen aperture instead of A

- The K30 does not work anymore, the display goes off and there is no action.

Strange but so it is. Maybe (allthough I can't think of any reason) this is because all K30's I repaired have the modified K50 1.10 firmware .

stevebrot · 09-14-2019, 10:56 AM

Originally posted by photogem

The K5II is in best order. So are my KP and K3II:

Which means I tested this on those as well, they behave all like the K5II and thus work in AV-mode with an A-Lens preset on a chose aperture...

I am thinking I misunderstood you. Let me get this straight...

None of these cameras (K30/K-50/K-500 included) is supposed to stop down in Av mode when an A-lens is set to other than the "A" position, though the camera will meter for the wide-open aperture and will take a picture.*
The OP's K-50 has aperture control failure and breaks the rule above by stopping down to the aperture set on the lens. Comments from other users with aperture control failure confirm the OP's discovery.
Your K-5II works the same as your K-3II and KP as well as the repaired K-50 and K-500, meaning that they work according to the rule in #1 above and do not stop down in Av mode, but do allow a metered photo to be taken.
The unrepaired K-50 works the same as reported by the OP and allows stop-down to the aperture ring setting in Av mode.
The repaired K-30 (hacked K-50 firmware) fails to fire shutter with an A-lens set to other than the "A" position and the camera in Av mode. The display also fails.

The repaired K-30 behavior is strange and if traceable to the hacked firmware, might be a caution against using that hack. You might want to contact the firmware author with your observation. Edit: Assuming the K-30 had been set to enable aperture ring and that the display was not failing due to other issue.

Steve

* At least that is how the user manuals read.

Last edited by stevebrot; 09-19-2019 at 07:50 AM.

**photogem** · 09-18-2019, 10:01 PM

Originally posted by stevebrot

The repaired K-30 behavior is strange and if traceable to the hacked firmware, might be a caution against using that hack. You might want to contact the firmware author with your observation.

I have to wait until I have another K-30 with a stuck solenoid to do further tests.
Then I can check its behaviour with the original firmware.

**photogem** · 09-25-2019, 06:44 AM - **1 Like**

Update: Came across a Pentax K-30 with firmware 1.06:

Same (for the K-30 normal!) behaviour!

This method using an A-lens in AV-mode but other than A-setting
does NOT WORK with the K-30!

No matter if the solenoid is functioning or not!

I have tried it with:

- F50/1,7
- F35-70/3,5-4-5 Macro
- D-FA 100/2,8 Macro
- A50/1,2

no difference!

m42man · 09-25-2019, 10:57 AM

Originally posted by photogem

Update: Came across a Pentax K-30 with firmware 1.06:

Same (for the K-30 normal!) behaviour!

This method using an A-lens in AV-mode but other than A-setting
does NOT WORK with the K-30!

No matter if the solenoid is functioning or not!

I have tried it with:

- F50/1,7
- F35-70/3,5-4-5 Macro
- D-FA 100/2,8 Macro
- A50/1,2

no difference!

Ah! So - just to clarify - a firmware update to 1.06 returns the K30/K50 (K500?) to business as usual?

Very interesting (I can imagine there will be some users with that firmware who will want to return it to an earlier version).

Thanks for the info!

**photogem** · 09-25-2019, 06:42 PM

Originally posted by m42man

Ah! So - just to clarify - a firmware update to 1.06 returns the K30/K50 (K500?) to business as usual?
Very interesting (I can imagine there will be some users with that firmware who will want to return it to an earlier version).
Thanks for the info!

No, the K30 behaves exactly the same with firmware 1.10 or 1.06.

m42man · 09-26-2019, 03:01 AM

Originally posted by photogem

No, the K30 behaves exactly the same with firmware 1.10 or 1.06.

Still unclear to me.

Does your K-30 with broken solenoid stop down a lens with aperture set by its ring in Av mode a) with firmware 1.00 and b) with firmware 1.06?

**photogem** · 09-26-2019, 11:27 PM

Originally posted by m42man

Still unclear to me.

Does your K-30 with broken solenoid stop down a lens with aperture set by its ring in Av mode a) with firmware 1.00 and b) with firmware 1.06?

No, it doesn't stop down! I don't have one with firmware 1.00 so I only could check this with

- firmware 1.06
- firmware 1.10 (the unofficial firmware)

In both cases the K-30 will just not fire, when pushing the shutter release button the LCD goes off and nothing happens.
As if a short circuit happens.
Can't be linked to AF because I tried it with manual A-lenses as well.

hnikesch · 11-04-2019, 02:51 PM

Looks like it's a good thing I updated my failed K30 to the K50 hack as I have several FA and K lenses that didn't see much use. My KP gets the DA lenses and the Broken K30 works great in AV mode with FA and K lenses. One more reason for not opening the K30 and destroying my KM for it's solenoid.

photogem is the K2000 flash solenoid a good white solenoid, I can live without the popup flash

**photogem** · 11-04-2019, 10:16 PM

Originally posted by hnikesch

photogem is the K2000 flash solenoid a good white solenoid, I can live without the popup flash

If it is white-coloured, yes. As far as I can tell it was more in Europe that they already tested the green solenoids in the flash with the K-m
k-x etc. but not USA.

You can install the green solenoid into the flash-circuit of your k-m/2000.

09-14-2019, 10:56 AM	#22
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by photogem The K5II is in best order. So are my KP and K3II: Which means I tested this on those as well, they behave all like the K5II and thus work in AV-mode with an A-Lens preset on a chose aperture... I am thinking I misunderstood you. Let me get this straight... None of these cameras (K30/K-50/K-500 included) is supposed to stop down in Av mode when an A-lens is set to other than the "A" position, though the camera will meter for the wide-open aperture and will take a picture.* The OP's K-50 has aperture control failure and breaks the rule above by stopping down to the aperture set on the lens. Comments from other users with aperture control failure confirm the OP's discovery. Your K-5II works the same as your K-3II and KP as well as the repaired K-50 and K-500, meaning that they work according to the rule in #1 above and do not stop down in Av mode, but do allow a metered photo to be taken. The unrepaired K-50 works the same as reported by the OP and allows stop-down to the aperture ring setting in Av mode. The repaired K-30 (hacked K-50 firmware) fails to fire shutter with an A-lens set to other than the "A" position and the camera in Av mode. The display also fails. The repaired K-30 behavior is strange and if traceable to the hacked firmware, might be a caution against using that hack. You might want to contact the firmware author with your observation. Edit: Assuming the K-30 had been set to enable aperture ring and that the display was not failing due to other issue. Steve * At least that is how the user manuals read. Last edited by stevebrot; 09-19-2019 at 07:50 AM.

09-18-2019, 10:01 PM	#23
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by stevebrot The repaired K-30 behavior is strange and if traceable to the hacked firmware, might be a caution against using that hack. You might want to contact the firmware author with your observation. I have to wait until I have another K-30 with a stuck solenoid to do further tests. Then I can check its behaviour with the original firmware. Last edited by photogem; 09-18-2019 at 10:09 PM.

09-25-2019, 06:44 AM - 1 Like	#24
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Pentax K-30 does not work in AV if A-lens is other than A-Setting! Update: Came across a Pentax K-30 with firmware 1.06: Same (for the K-30 normal!) behaviour! This method using an A-lens in AV-mode but other than A-setting does NOT WORK with the K-30! No matter if the solenoid is functioning or not! I have tried it with: - F50/1,7 - F35-70/3,5-4-5 Macro - D-FA 100/2,8 Macro - A50/1,2 no difference! Last edited by photogem; 09-25-2019 at 06:58 AM.

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09-08-2019, 11:45 PM	#16
K2 to K50 Loyal Site Supporter Join Date: Jan 2019 Location: Ipswich QLD Australia Photos: Gallery \| Albums Posts: 4,790	Originally posted by pschlute Not quite. Changing the aperture using the ring on a K-mount lens will not stop the lens down. The lens is stopped down during capture. This enables open aperture focussing. But the mounts used on a modern DSLR are such that the stop-down will only take place in M or B or X mode. In Av mode (and any other auto mode) the lens will not be stopped down at capture. ......... ps. M42 lenses behave differently OK, seems I have been misunderstanding how the M lenses work on my K50 or KP. This forum continues to be an education!

09-09-2019, 04:48 PM	#17
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by m42man So, if you're unlucky enough to get aperture block failure, you get the benefit of an arguably superior option when using a legacy lens. Except that you have to remember to set exposure compensation to match the aperture ring setting and even then the metering might not be right. I don't know that this is better than simply using M mode on a properly functioning camera. Steve

09-10-2019, 02:30 AM	#18
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623 Original Poster	Originally posted by stevebrot Except that you have to remember to set exposure compensation to match the aperture ring setting and even then the metering might not be right. I don't know that this is better than simply using M mode on a properly functioning camera. Steve Well, equally, you can set an aperture (perhaps to maximise sharpness) and then shoot away without needing to remember to use the green button before each shot (assuming lighting is varying). But why do you say the metering might not be right? Metering is carried out wide open, just like a normal camera, and the appropriate shutter speed set according to the chosen shooting aperture, just like a normal camera. Exposure compensation is effectively just the same as the camera actually knowing the (relative) aperture (whether for a vintage SLR via a non-crippled K-mount linkage, or by the user selecting an aperture using a thumbwheel). So you'd expect the same exposure accuracy as you get for a lens in normal use. Stop-down metering sounds like it would be immune to exposure errors due to the actual aperture being inaccurately implemented by the lens, but in my experience this seems to be outweighed by errors presumably induced by the metering system coping badly with varying apertures. Anyway, it's nice to have the choice. I'd suggest users try both methods and compare results for themselves.

09-13-2019, 10:53 AM	#19
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by Adam All Pentax cameras should behave this way AFAIK- you just need to allow the use of the aperture ring through the menu. I was curious about it but wanted to wait until I had a Pentax with a stuck solenoid in my house. Today a K-50 arrived, typical symptons. I tried it the way member m42man suggested (lens: F50/1,7) and came to the same conclusions! It works exactly the way he described. Then I took an already repaired K-30, set it on AV but the lens not on A but a chose aperture: Opposite you thought it did not work (wait, more will come!) It would not fire when I changed the A-ring to any other position than A. As soon as I press the the release button, the display goes off, as if there would be some kind of shortage and the K30 would not fire. Back on A and all is fine. So I tried it with the K5II and suprise: It works the same way as the K-30 with the stuck solenoid! I then opened the K-50 for repair but then placed the battery back in and then the F50/1,7: The solenoid does not actuate at all. Then I exchanged the solenoid (white solenoid): All was working as usual and as it should. I then tested it again in AV mode but the lens not on A but a chosen aperture and very strangly it works .. and yet, the solenoid does not actuate! So I have no explanation at all but have to wait until further K30's or similar arrive here and I can test. Last edited by photogem; 09-14-2019 at 03:34 AM.

09-13-2019, 12:28 PM	#20
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by photogem So I tried it with the K5II and suprise: It works the same way as the K-30 with the stuck solenoid! The behavior of the K-30 with the stuck solenoid makes sense, assuming the camera treats all non-A lenses as "wide open" in all auto-exposure modes. A K-5II behaving the same way is completely unexpected unless the camera is broken. No stop-down with a non-A lens has been the norm in other than M, X, and B modes with crippled mount cameras pretty much forever.* Steve * All dSLRs. I don't know about the crippled mount film cameras.

09-14-2019, 03:42 AM	#21
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by stevebrot The behavior of the K-30 with the stuck solenoid makes sense, assuming the camera treats all non-A lenses as "wide open" in all auto-exposure modes. A K-5II behaving the same way is completely unexpected unless the camera is broken. The K5II is in best order. So are my KP and K3II: Which means I tested this on those as well, they behave all like the K5II and thus work in AV-mode with an A-Lens preset on a chose aperture. I then tested it on another K50 as well as on a K500 and another K30 (those are around in the family because I repaired quite a few): With a stuck solenoid all behave the same and can be used this limited way in AV-mode. The solenoid does not actuate if an A-lens is not on A but on a chose aperture But as soon as the solenoid is alright again, we have two different results: - The K50/K500 work in AV-mode with chosen aperture instead of A - The K30 does not work anymore, the display goes off and there is no action. Strange but so it is. Maybe (allthough I can't think of any reason) this is because all K30's I repaired have the modified K50 1.10 firmware .

09-25-2019, 10:57 AM	#25
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623 Original Poster	Originally posted by photogem Update: Came across a Pentax K-30 with firmware 1.06: Same (for the K-30 normal!) behaviour! This method using an A-lens in AV-mode but other than A-setting does NOT WORK with the K-30! No matter if the solenoid is functioning or not! I have tried it with: - F50/1,7 - F35-70/3,5-4-5 Macro - D-FA 100/2,8 Macro - A50/1,2 no difference! Ah! So - just to clarify - a firmware update to 1.06 returns the K30/K50 (K500?) to business as usual? Very interesting (I can imagine there will be some users with that firmware who will want to return it to an earlier version). Thanks for the info!

09-25-2019, 06:42 PM	#26
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by m42man Ah! So - just to clarify - a firmware update to 1.06 returns the K30/K50 (K500?) to business as usual? Very interesting (I can imagine there will be some users with that firmware who will want to return it to an earlier version). Thanks for the info! No, the K30 behaves exactly the same with firmware 1.10 or 1.06.

09-26-2019, 03:01 AM	#27
m42man Veteran Member Join Date: Jan 2010 Location: Southern England Posts: 623 Original Poster	Originally posted by photogem No, the K30 behaves exactly the same with firmware 1.10 or 1.06. Still unclear to me. Does your K-30 with broken solenoid stop down a lens with aperture set by its ring in Av mode a) with firmware 1.00 and b) with firmware 1.06?

09-26-2019, 11:27 PM	#28
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by m42man Still unclear to me. Does your K-30 with broken solenoid stop down a lens with aperture set by its ring in Av mode a) with firmware 1.00 and b) with firmware 1.06? No, it doesn't stop down! I don't have one with firmware 1.00 so I only could check this with - firmware 1.06 - firmware 1.10 (the unofficial firmware) In both cases the K-30 will just not fire, when pushing the shutter release button the LCD goes off and nothing happens. As if a short circuit happens. Can't be linked to AF because I tried it with manual A-lenses as well.

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11-04-2019, 02:51 PM	#29
hnikesch Veteran Member Join Date: May 2009 Location: Michigan, USA Photos: Albums Posts: 1,316	Looks like it's a good thing I updated my failed K30 to the K50 hack as I have several FA and K lenses that didn't see much use. My KP gets the DA lenses and the Broken K30 works great in AV mode with FA and K lenses. One more reason for not opening the K30 and destroying my KM for it's solenoid. photogem is the K2000 flash solenoid a good white solenoid, I can live without the popup flash

11-04-2019, 10:16 PM	#30
photogem Site Supporter Join Date: Apr 2015 Posts: 3,519	Originally posted by hnikesch photogem is the K2000 flash solenoid a good white solenoid, I can live without the popup flash If it is white-coloured, yes. As far as I can tell it was more in Europe that they already tested the green solenoids in the flash with the K-m k-x etc. but not USA. You can install the green solenoid into the flash-circuit of your k-m/2000.