K-1's more than random overexposure with FAJ 18-35mm and FA Ltd 77mm

CXP68 · 01-28-2017, 12:06 AM

Hi,

My Pentax K-1 (bought last August through CR Kennedy, Melbourne) has experienced occasional overexposure (sometimes the whole picture was totally overposed). But I just thought it's an operating error and had ignored it until yesterday I had more frequent overexposure pictures (please see a few attached for comparison). I used two lenses as shown on the title. I used multi-segment exposure mode for those pictures and usually applied -0.7 exposure compensation or more.

Given your experience, I would like to know if this indicates a faulty camera or there might be an easy fix on my part. I read on another Pentaxforums thread about a similar problem with K-3 (https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/302516-r...d-16-85-a.html). Just as a background, I have a K-3 and never seem to have the same problem (maybe once or twice during the past few years), and I am now travelling and don't have K-3 with me to test whether it's the lenses' problem or K-1's problem. I shot K-3 often with FA Ltd 77mm and it seems all fine, but yesterday's consistent overexposure with the same lens on K-1 has me very concerned.

Any advice and help would be greatly appreciated.

CX

Attached Images

View Picture EXIF

View Picture EXIF

biz-engineer · 01-28-2017, 02:05 AM

The fix is either manual exposure, or send the camera for repair.

BROO · 01-28-2017, 02:35 AM

Your ISO is different between shots in the EXIF data. Are you inadvertently changing it with the third dial on the K1?

rawr · 01-28-2017, 02:47 AM

Your ISO is going all over the place, from ISO 100 to ISO 3200. Limit it to a narrower range - eg ISO 100-800 perhaps. Plus your last FA77 image says you were using manual exposure plus manual WB.

Perhaps switch to centre-weighted average for your metering and see if that makes a difference.

biz-engineer · 01-28-2017, 04:06 AM

oupps i did not see it was manual exposure... in that case I don't think it's a camera issue.

stevebrot · 01-28-2017, 04:27 AM

I remember your previous problem which definitely pointed to faulty aperture actuation, probably with the lens. In that case, the overexposure happened for photos having identical aperture, shutter, and ISO settings.

Based on the full EXIF, your photos above seem to indicate metering error (EV varies by factor of 4 on top pair). By any chance are you set up to have exposure follow focus point? (Focus point is "zone select, near left, single point", on the top pair, but framing is different.) You are using TAv mode and Av mode (presumed auto-ISO), so lazy aperture or aperture controller is another possible cause with the lens not fully opening between exposures.

Steve

stevebrot · 01-28-2017, 04:34 AM

Originally posted by biz-engineer

oupps i did not see it was manual exposure... in that case I don't think it's a camera issue.

The top two are TAv mode and the bottom two are Av mode (presumably auto-ISO). The metered EVs are way different between the top and bottom for each pair.

Steve

Last edited by stevebrot; 01-28-2017 at 04:44 AM.

stevebrot · 01-28-2017, 05:01 AM

Originally posted by stevebrot

Based on the full EXIF, your photos above seem to indicate metering error (EV varies by factor of 4 on top pair).

Just noticed that AE Lock was engaged for all four photos (???). Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo?

Steve

rawr · 01-28-2017, 05:22 AM

Originally posted by stevebrot

Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo?

Full EXIF from a straight-out-of-camera JPEG image would be nice to identify the camera settings. Hard to do that from the current stripped-down EXIF.

stevebrot · 01-28-2017, 09:33 AM

Originally posted by rawr

Full EXIF from a straight-out-of-camera JPEG image would be nice to identify the camera settings. Hard to do that from the current stripped-down EXIF.

The posted photos are SOOC JPEG, though shot at ridiculously low resolution.* I was able to extract the full set of metadata from all four images using ExifTool.

Steve

* They may also be embedded thumbnails...both have full EXIF, IIRC

rawr · 01-28-2017, 06:28 PM

Originally posted by stevebrot

The posted photos are SOOC JPEG, though shot at ridiculously low resolution

True. I should have EXIFTOOL'd them earlier. Lots of metadata indeed for a 50K JPEG! Probably about 10% of the byte count.

I also noticed AE Lock was active - eg on the last FA 77 image. Hence AE was 'frozen'. Easy to accidentally press that button.

**DDoram** · 01-28-2017, 07:59 PM

I have had the same issue with my K1 but it only occurs about 1 per thousand pics.

CXP68 · 01-28-2017, 11:58 PM

Originally posted by stevebrot

Just noticed that AE Lock was engaged for all four photos (???). Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo?

Steve

Many thanks Steve for pointing that out. I just checked my camera custom setting and indeed "AE-L with AF Locked" was set as "On" (I might did this when doing some portraits a while ago but then forgot to change this back). I think that could well be the source of problem. I had thought that this would not affect exposure too much under the multi-segment (as opposed to spot) metering mode, but I may be wrong here, hence the exposed pictures (but then I rarely got under-exposed pictures under these conditions). I will do some new tests and see if changing "AE-L with AF Locked" to "Off" will fix the problem - fingers crossed. Thanks again!

---------- Post added 01-29-17 at 12:01 AM ----------

Originally posted by rawr

True. I should have EXIFTOOL'd them earlier. Lots of metadata indeed for a 50K JPEG! Probably about 10% of the byte count.

I also noticed AE Lock was active - eg on the last FA 77 image. Hence AE was 'frozen'. Easy to accidentally press that button.

Many thanks for helping zero in on the AE lock issue. I will do new tests and report back if this is the problem.

---------- Post added 01-29-17 at 12:07 AM ----------

Originally posted by BROO

Your ISO is different between shots in the EXIF data. Are you inadvertently changing it with the third dial on the K1?

The second dial was set on Wifi and so I wouldn't be able to accidentally change the ISO between different shots through the third dial. But thanks for the reminder.

CXP68 · 01-29-2017, 12:20 AM

Originally posted by biz-engineer

oupps i did not see it was manual exposure... in that case I don't think it's a camera issue.

These pictures were shot with either aperture priority or TAv, not full manual exposure. Attached at the bottom is a screenshot of that totally exposure picture's shooting info as shown in Digital Camera Utility 5.0, which may be more accurate.

---------- Post added 01-29-17 at 12:25 AM ----------

Originally posted by stevebrot

The posted photos are SOOC JPEG, though shot at ridiculously low resolution.* I was able to extract the full set of metadata from all four images using ExifTool.

Steve

* They may also be embedded thumbnails...both have full EXIF, IIRC

Sorry Steve for the low-resolution pictures - I resized them before uploading onto the site just in case the larger file size slows down the uploading. I normally shoot both RAW and JPEG in maximum resolution.

CXP68 · 01-29-2017, 02:03 AM

Thank you all for the quick and very helpful replies and suggestions. I just did some test shots. When AE-L with AF was turned on, I again had over-exposed shots. When "Off", the exposures were consistently normal. So the 'On' setting for AE-L with AF seems to be the problem. It's a big relief that it's user error on my part. Many thanks again for helping out and I really appreciate it.

01-28-2017, 04:27 AM	#6
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	I remember your previous problem which definitely pointed to faulty aperture actuation, probably with the lens. In that case, the overexposure happened for photos having identical aperture, shutter, and ISO settings. Based on the full EXIF, your photos above seem to indicate metering error (EV varies by factor of 4 on top pair). By any chance are you set up to have exposure follow focus point? (Focus point is "zone select, near left, single point", on the top pair, but framing is different.) You are using TAv mode and Av mode (presumed auto-ISO), so lazy aperture or aperture controller is another possible cause with the lens not fully opening between exposures. Steve Last edited by stevebrot; 01-28-2017 at 04:44 AM.

01-28-2017, 11:58 PM	#13
CXP68 New Member Join Date: Feb 2015 Location: Victoria Posts: 12 Original Poster	Originally posted by stevebrot Just noticed that AE Lock was engaged for all four photos (???). Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo? Steve Many thanks Steve for pointing that out. I just checked my camera custom setting and indeed "AE-L with AF Locked" was set as "On" (I might did this when doing some portraits a while ago but then forgot to change this back). I think that could well be the source of problem. I had thought that this would not affect exposure too much under the multi-segment (as opposed to spot) metering mode, but I may be wrong here, hence the exposed pictures (but then I rarely got under-exposed pictures under these conditions). I will do some new tests and see if changing "AE-L with AF Locked" to "Off" will fix the problem - fingers crossed. Thanks again! ---------- Post added 01-29-17 at 12:01 AM ---------- Originally posted by rawr True. I should have EXIFTOOL'd them earlier. Lots of metadata indeed for a 50K JPEG! Probably about 10% of the byte count. I also noticed AE Lock was active - eg on the last FA 77 image. Hence AE was 'frozen'. Easy to accidentally press that button. Many thanks for helping zero in on the AE lock issue. I will do new tests and report back if this is the problem. ---------- Post added 01-29-17 at 12:07 AM ---------- Originally posted by BROO Your ISO is different between shots in the EXIF data. Are you inadvertently changing it with the third dial on the K1? The second dial was set on Wifi and so I wouldn't be able to accidentally change the ISO between different shots through the third dial. But thanks for the reminder. Last edited by CXP68; 01-29-2017 at 01:44 AM.

01-29-2017, 12:20 AM	#14
CXP68 New Member Join Date: Feb 2015 Location: Victoria Posts: 12 Original Poster	Originally posted by biz-engineer oupps i did not see it was manual exposure... in that case I don't think it's a camera issue. These pictures were shot with either aperture priority or TAv, not full manual exposure. Attached at the bottom is a screenshot of that totally exposure picture's shooting info as shown in Digital Camera Utility 5.0, which may be more accurate. ---------- Post added 01-29-17 at 12:25 AM ---------- Originally posted by stevebrot The posted photos are SOOC JPEG, though shot at ridiculously low resolution.* I was able to extract the full set of metadata from all four images using ExifTool. Steve * They may also be embedded thumbnails...both have full EXIF, IIRC Sorry Steve for the low-resolution pictures - I resized them before uploading onto the site just in case the larger file size slows down the uploading. I normally shoot both RAW and JPEG in maximum resolution. Attached Images Last edited by CXP68; 01-29-2017 at 12:38 AM.

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01-28-2017, 02:05 AM	#2
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,225	The fix is either manual exposure, or send the camera for repair.

01-28-2017, 02:35 AM	#3
BROO Veteran Member Join Date: Feb 2016 Photos: Gallery \| Albums Posts: 655	Your ISO is different between shots in the EXIF data. Are you inadvertently changing it with the third dial on the K1?

01-28-2017, 02:47 AM	#4
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Your ISO is going all over the place, from ISO 100 to ISO 3200. Limit it to a narrower range - eg ISO 100-800 perhaps. Plus your last FA77 image says you were using manual exposure plus manual WB. Perhaps switch to centre-weighted average for your metering and see if that makes a difference.

01-28-2017, 04:06 AM	#5
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,225	oupps i did not see it was manual exposure... in that case I don't think it's a camera issue.

01-28-2017, 04:34 AM	#7
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by biz-engineer oupps i did not see it was manual exposure... in that case I don't think it's a camera issue. The top two are TAv mode and the bottom two are Av mode (presumably auto-ISO). The metered EVs are way different between the top and bottom for each pair. Steve Last edited by stevebrot; 01-28-2017 at 04:44 AM.

01-28-2017, 05:01 AM	#8
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by stevebrot Based on the full EXIF, your photos above seem to indicate metering error (EV varies by factor of 4 on top pair). Just noticed that AE Lock was engaged for all four photos (???). Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo? Steve

01-28-2017, 05:22 AM	#9
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Originally posted by stevebrot Are you set to AE-L when AF locks or was the AE inadvertently locked at the wrong exposure before taking the photo? Full EXIF from a straight-out-of-camera JPEG image would be nice to identify the camera settings. Hard to do that from the current stripped-down EXIF.

01-28-2017, 09:33 AM	#10
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by rawr Full EXIF from a straight-out-of-camera JPEG image would be nice to identify the camera settings. Hard to do that from the current stripped-down EXIF. The posted photos are SOOC JPEG, though shot at ridiculously low resolution.* I was able to extract the full set of metadata from all four images using ExifTool. Steve * They may also be embedded thumbnails...both have full EXIF, IIRC

01-28-2017, 06:28 PM	#11
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Originally posted by stevebrot The posted photos are SOOC JPEG, though shot at ridiculously low resolution True. I should have EXIFTOOL'd them earlier. Lots of metadata indeed for a 50K JPEG! Probably about 10% of the byte count. I also noticed AE Lock was active - eg on the last FA 77 image. Hence AE was 'frozen'. Easy to accidentally press that button.

01-28-2017, 07:59 PM	#12
DDoram Site Supporter Join Date: Jan 2009 Location: Edmonton, Alberta Canada Posts: 632	I have had the same issue with my K1 but it only occurs about 1 per thousand pics.

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01-29-2017, 02:03 AM	#15
CXP68 New Member Join Date: Feb 2015 Location: Victoria Posts: 12 Original Poster	Thank you all for the quick and very helpful replies and suggestions. I just did some test shots. When AE-L with AF was turned on, I again had over-exposed shots. When "Off", the exposures were consistently normal. So the 'On' setting for AE-L with AF seems to be the problem. It's a big relief that it's user error on my part. Many thanks again for helping out and I really appreciate it.