[Paul Evans]

Yesterday morning I was out photographing the dawn on top of Mam Tor in Derbyshire, UK. Temps probably around -2 degrees C. I was out for around 3 hrs, standing around in the cold. I used various lenses, 16-45, 35mm Macro and towards the end of the session, I had the 77mm limited on - had two weird exposures. Took loads of frames that were fine, but for two exposures only, close but not sequential to each other, I think (but can't swear) that the camera display indicated 1/30 sec exposure. The shutter actually stayed open for 30 secs (so totally white frame was the result). I had ISO set to 80 throughout the session, camera in Aperture Priority, battery not full (over 300 shots taken since full charge) but not flat either. Before and since the camera has behaved perfectly.
Could be user error but no idea what I've done...anyone have any bright ideas?
Done a search but can't see any mention of similar problems.
I've kept the affected images so can query the metadata.

Cheers all

Paul

[derekkite]

I've had shots like that with a dodgy adaptall mount. Could be the mount connections were not being made or some short due to condensation. The back of my camera gets dripping wet from breath condensation at those temperatures.

[Paul Evans]

That kind of sounds feasible - mounting and unmounting lenses, possible some connection slightly dodgy or bit of damp somewhere...

Paul

[Paul Evans]

Just checked the AE metering segment EXIF data on the affected images. Pics taken immediately before and after have AE metering segments 1-16 reading values between 11 and 14. The affected images (taken of similar subjects - hills and moors - in the same light) have AE metering segment values of -2.6 to -2.9. So looks like the camera is setting a very long shutter speed (30 secs) because it believes there is no light.....worrying...

Paul

[jbinpg]

When I have had something similar happen to me, I have either accidentally pressed the green button or the AE lock. Just sayin....

[SpecialK]

I've had a few frames in a sequence go very over or very under for no reason.

https://www.pentaxforums.com/forums/pentax-k-5-forum/161077-odd-exposures.html

[Paul Evans]

Hmm - if I had pressed the AE lock before taking the lens cap off, would it have produced these symptoms? Cold fingers in gloves could possibly have done that....I'll experiment a bit.
"Being a muppet" is a much happier answer than "my camera has a weird intermittent fault that nobody else has".

Cheers guys

Paul

[Dionisis_K]

From what you are telling i m' pretty sure that was the issue.. Don't worry your camera should be fine...

[Paul Evans]

Diagnosis confirmed guys - user error.
When I check the EXIF data for these frames, AE lock is engaged and the metering segment data is all blacks. Phew, I can relax (and feel slightly embarrassed) now.
Thanks for your input. Handy thing that EXIF data!
One followup question - my EXIF utility - PhotoME - shows data for 16 AE metering segments, the K5 has 77 segment metering. Anyone know why only 16 are shown? Is this a PhotoME limitation?

Cheers

Paul

[jbinpg]

Glad you got the AE lock sorted, Paul. As for metering segments used, sounds like you have it in center-weighted metering mode. You need to switch to multi-segment metering which examines the whole sensor area for all 77 zones to be calculated. The metering mode switch is immediately below the exposure mode dial.

Jack