One OVER and one UNDER exposed shot with the K-70

RobSpain · 09-20-2021, 02:13 AM

Just started to have an unusual experience with my K-70. When switching on (after the camera has been OFF for a few hours), the very first shot using the OVF is UNDER exposed. Again, with the camera OFF for a while and using LV, the very first shot is OVER exposed. Thereafter, using either OVF or LV all shots are perfectly exposed. I was using a fully charged battery. To ensure it’s not a lens problem, I’ve repeated the above using both the 18-50mm kit lens and the Sigma 10-20mm f/3.5, with the same result. I’ve also tried this test on a daily bases for the last couple of weeks and the reoccurrence is as regular as clockwork!

The camera is 3 years old with around 30,000 shots, mostly HDR as I use the camera for real estate photography. I’ve not had any problems up to now but this started just recently. Of course I’ve read much on the subject of K-70/K-50 etc. shutter failures but I don’t think I’ve ever seen a post detailing the above abnormality of 1 under and 1 over, and thereafter everything OK.

Any thoughts?

TIA! Robert

pschlute · 09-20-2021, 02:29 AM

Originally posted by RobSpain

mostly HDR

It sounds like the camera is still in HDR mode when you switch it back on.

RobSpain · 09-20-2021, 02:40 AM

Originally posted by pschlute

It sounds like the camera is still in HDR mode when you switch it back on.

No. It was in AV priority. EV compensation was zero.

biz-engineer · 09-20-2021, 03:07 AM

Originally posted by RobSpain

No. It was in AV priority. EV compensation was zero.

Pentax cameras can be in AV priority, with EV compensation = 0 , and HDR enabled. HDR mode comes on top of ~~drive~~ exposure modes such as Sv,Tv, Av, TAv, P, M etc. Exposure compensation and HDR are two independant things, you can shoot HDR images with any exposure compensation setting.

Last edited by biz-engineer; 09-20-2021 at 03:23 AM.

RobSpain · 09-20-2021, 03:14 AM

Originally posted by biz-engineer

Pentax cameras can be in AV priority, with EV compensation = 0 , and HDR enabled. HDR mode comes on top of drive modes such as Sv,Tv, Av, TAv, P, M etc. Exposure compensation and HDR are two independant things, you can shoot HDR images with any exposure compensation setting.

Yes, I'm aware of that, but no, it was set to single drive mode. I've just switched the camera on again right now, taken the first shot with the OVF, and again the first shot is under exposed, the second and subsequent shots are perfect.

biz-engineer · 09-20-2021, 03:25 AM

Originally posted by RobSpain

Yes, I'm aware of that, but no, it was set to single drive mode. I've just switched the camera on again right now, taken the first shot with the OVF, and again the first shot is under exposed, the second and subsequent shots are perfect.

maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not.

RobSpain · 09-20-2021, 03:27 AM

Originally posted by biz-engineer

maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not.

I'll leave the camera off a little while more and then try that. I'll get back...

Right, I've just tried the DoF simulation using LV and the first shot is OVER exposed as per my original post above. Thereafter, every shot is exposed correctly. So if nothing else, the fault is very consistent! Does this mean that I have a solenoid problem, or not?

Last edited by RobSpain; 09-20-2021 at 04:40 AM.

RobSpain · 09-20-2021, 04:42 AM

Originally posted by biz-engineer

maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not.

I have tried that and replied above...

pschlute · 09-20-2021, 06:17 AM

Are you using USER modes ?

Wasp · 09-20-2021, 07:27 AM

It could be the harbinger of the dreaded aperture block failure...

Tutorial: Detection of aperture block failure on Pentax DLSRs with solenoid - PentaxForums.com

K70 aperture block? - PentaxForums.com

biz-engineer · 09-20-2021, 07:58 AM

Originally posted by RobSpain

Does this mean that I have a solenoid problem, or not?

I can't tell. If you still get the first exposure underexposed after having "exercised" the aperture mechanism via DoF preview, and you also "exercised" the shutter by going in Live View On and Off. Try very fast shutter speed (1/4000) at high ISO and slow shutter speed (1 second) at base ISO (100). If you still don't find anything, it looks more like another problem, perhaps a firmware problem or a metering problem. Make sure to set the camera exposure to manual mode, so that ISO, shutter speed and aperture settings are fixed. What the exif says for the first shot, second shot etc... are exposure settings the same? Other possibilities firmware went amok, then do a full camera reset first by removing the battery and back in again, or even by restoring all settings to factory settings.

**Bob 256** · 09-20-2021, 08:01 AM

Dumb question but have you checked to see if any bracketing modes are engaged? I would think the camera would try to take two sequential pictures (one over and one under) but something to consider???? Ditto on what biz-engineer said in previous post about resetting & reloading firmware.

RobSpain · 09-20-2021, 08:38 AM

Originally posted by pschlute

Are you using USER modes ?

i indeed do use and have set up 2 of the user mode dials for different HDR scenarios, but neither of these were in play with regard to the reported problem above.

---------- Post added 09-20-21 at 05:41 PM ----------

Originally posted by Bob 256

Dumb question but have you checked to see if any bracketing modes are engaged? I would think the camera would try to take two sequential pictures (one over and one under) but something to consider???? Ditto on what biz-engineer said in previous post about resetting & reloading firmware.

No, they are definitely not. Yes, I'm gonna try some other settings are per the biz-engineer.

pschlute · 09-20-2021, 12:49 PM

Sounds like you need a new camera in that case.

**DeepThrob** · 09-20-2021, 02:03 PM

Did you reset it ?

09-20-2021, 02:13 AM	#1
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488	One OVER and one UNDER exposed shot with the K-70 Just started to have an unusual experience with my K-70. When switching on (after the camera has been OFF for a few hours), the very first shot using the OVF is UNDER exposed. Again, with the camera OFF for a while and using LV, the very first shot is OVER exposed. Thereafter, using either OVF or LV all shots are perfectly exposed. I was using a fully charged battery. To ensure it’s not a lens problem, I’ve repeated the above using both the 18-50mm kit lens and the Sigma 10-20mm f/3.5, with the same result. I’ve also tried this test on a daily bases for the last couple of weeks and the reoccurrence is as regular as clockwork! The camera is 3 years old with around 30,000 shots, mostly HDR as I use the camera for real estate photography. I’ve not had any problems up to now but this started just recently. Of course I’ve read much on the subject of K-70/K-50 etc. shutter failures but I don’t think I’ve ever seen a post detailing the above abnormality of 1 under and 1 over, and thereafter everything OK. Any thoughts? TIA! Robert

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09-20-2021, 02:29 AM	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	Originally posted by RobSpain mostly HDR It sounds like the camera is still in HDR mode when you switch it back on.

09-20-2021, 02:40 AM	#3
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488 Original Poster	Originally posted by pschlute It sounds like the camera is still in HDR mode when you switch it back on. No. It was in AV priority. EV compensation was zero.

09-20-2021, 03:07 AM	#4
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by RobSpain No. It was in AV priority. EV compensation was zero. Pentax cameras can be in AV priority, with EV compensation = 0 , and HDR enabled. HDR mode comes on top of ~~drive~~ exposure modes such as Sv,Tv, Av, TAv, P, M etc. Exposure compensation and HDR are two independant things, you can shoot HDR images with any exposure compensation setting. Last edited by biz-engineer; 09-20-2021 at 03:23 AM.

09-20-2021, 03:14 AM	#5
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488 Original Poster	Originally posted by biz-engineer Pentax cameras can be in AV priority, with EV compensation = 0 , and HDR enabled. HDR mode comes on top of drive modes such as Sv,Tv, Av, TAv, P, M etc. Exposure compensation and HDR are two independant things, you can shoot HDR images with any exposure compensation setting. Yes, I'm aware of that, but no, it was set to single drive mode. I've just switched the camera on again right now, taken the first shot with the OVF, and again the first shot is under exposed, the second and subsequent shots are perfect.

09-20-2021, 03:25 AM	#6
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by RobSpain Yes, I'm aware of that, but no, it was set to single drive mode. I've just switched the camera on again right now, taken the first shot with the OVF, and again the first shot is under exposed, the second and subsequent shots are perfect. maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not.

09-20-2021, 03:27 AM	#7
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488 Original Poster	Originally posted by biz-engineer maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not. I'll leave the camera off a little while more and then try that. I'll get back... Right, I've just tried the DoF simulation using LV and the first shot is OVER exposed as per my original post above. Thereafter, every shot is exposed correctly. So if nothing else, the fault is very consistent! Does this mean that I have a solenoid problem, or not? Last edited by RobSpain; 09-20-2021 at 04:40 AM.

09-20-2021, 04:42 AM	#8
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488 Original Poster	Originally posted by biz-engineer maybe you have the infamous solenoid problem. Try do an DoF simulation to activate the aperture level a few times before taking the first shot, see if the first shot is still underexposed or not. I have tried that and replied above...

09-20-2021, 06:17 AM	#9
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	Are you using USER modes ?

09-20-2021, 07:27 AM	#10
Wasp Pentaxian Join Date: Mar 2017 Location: Pretoria Photos: Gallery Posts: 4,661	It could be the harbinger of the dreaded aperture block failure... Tutorial: Detection of aperture block failure on Pentax DLSRs with solenoid - PentaxForums.com K70 aperture block? - PentaxForums.com

09-20-2021, 07:58 AM	#11
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by RobSpain Does this mean that I have a solenoid problem, or not? I can't tell. If you still get the first exposure underexposed after having "exercised" the aperture mechanism via DoF preview, and you also "exercised" the shutter by going in Live View On and Off. Try very fast shutter speed (1/4000) at high ISO and slow shutter speed (1 second) at base ISO (100). If you still don't find anything, it looks more like another problem, perhaps a firmware problem or a metering problem. Make sure to set the camera exposure to manual mode, so that ISO, shutter speed and aperture settings are fixed. What the exif says for the first shot, second shot etc... are exposure settings the same? Other possibilities firmware went amok, then do a full camera reset first by removing the battery and back in again, or even by restoring all settings to factory settings.

09-20-2021, 08:01 AM	#12
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	Dumb question but have you checked to see if any bracketing modes are engaged? I would think the camera would try to take two sequential pictures (one over and one under) but something to consider???? Ditto on what biz-engineer said in previous post about resetting & reloading firmware.

09-20-2021, 08:38 AM	#13
RobSpain Pentaxian Join Date: Oct 2018 Location: Malaga province Posts: 488 Original Poster	Originally posted by pschlute Are you using USER modes ? i indeed do use and have set up 2 of the user mode dials for different HDR scenarios, but neither of these were in play with regard to the reported problem above. ---------- Post added 09-20-21 at 05:41 PM ---------- Originally posted by Bob 256 Dumb question but have you checked to see if any bracketing modes are engaged? I would think the camera would try to take two sequential pictures (one over and one under) but something to consider???? Ditto on what biz-engineer said in previous post about resetting & reloading firmware. No, they are definitely not. Yes, I'm gonna try some other settings are per the biz-engineer.

09-20-2021, 12:49 PM	#14
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	Sounds like you need a new camera in that case.

09-20-2021, 02:03 PM	#15
DeepThrob Site Supporter Join Date: Nov 2012 Location: Taos, New Mexico Posts: 295	Did you reset it ?