[corvin]

I've looked around and cannot find a thread on the subject. Forgive me if this has been discussed.

On three of our four K-3s, when we shoot in continuous mode, the first shot will be properly exposed and then the subsequent shots will be incredibly overexposed (same settings shown in the EXIF). All have 1.40 version of the firmware installed and I cannot find any setting differences that would cause this.

Seems to be a common problem (or repeated user error across three bodies).

Does anyone have experience with correcting this problem? Or guesses?

Thanks!

[stevebrot]

Seems to be a common problem (or repeated user error across three bodies).

Common with you, it appears! Levity aside, I will do a look-back for similar posts to see if they hold clues.

Does anyone have experience with correcting this problem? Or guesses?

Same lens or all lenses?
Exposure mode?

Can you provide a file link for an overexposed shot (DNG/PEF or in-camera JPEG with full EXIF intact)?


Steve

[Madaboutpix]

Have been using a K-3 for nearly five years, which has seen a fair share of use in continuous mode, and not noted a significant tendency to such worsening overexposure within bursts. Could it be that it occurs when you are panning or tracking subjects in motion and the light is changing? What kind of metering mode are you in?

Posting sample images showing the problem -- or better still, linking to full-res images with EXIFs -- could help a lot to pinpoint the problem and possibly come up with a solution, you know ...

[Dipsoid]

Are you using any automatic exposure mode? I find when I shoot aperture priority I get slight variations on exposure when using continuous mode, but that's likely normal. I've never had drastic exposure changes however.

[MetteHHH]

Sounds like you might have an aperture blade problem? This would occur if your lens has slow aperture blades that are unable to keep up with your frame rate - sounds like what I experience with my "sticky" copy of my DA 100mm f4 WR lens. Try searching for "sticky aperture blades" in the forums?

Which lens/lenses are mounted when the problem occurs?

[stevebrot]

Sounds like you might have an aperture blade problem? This would occur if your lens has slow aperture blades that are unable to keep up with your frame rate - sounds like what I experience with my "sticky" copy of my DA 100mm f4 WR lens. Try searching for "sticky aperture blades" in the forums?

Which lens/lenses are mounted when the problem occurs?

Thanks for noticing this thread. I am reviewing your thread from four years ago for clues.

Random overexposure problem getting worse! - PentaxForums.com

Did you ever get the problem resolved?


Steve

[stevebrot]

On three of our four K-3s

This is quite off-topic, but perhaps not. About a year ago you posted regarding problems with your four K-x bodies. Are you doing some sort of specialty shooting, by any chance?


Steve

[BigMackCam]

I've had my K-3 since not long after it was released, and have never experienced this problem (including just now when I tested it again). I'm on firmware version 1.30.

If the EXIF data shows the same ISO, shutter speed and aperture settings and nothing has changed in the scene, I can only think that there's an issue with the lens aperture control mechanism, or the camera's control mechanism for operating it.

Could you confirm if the issue is happening with more than one lens? Also, for the three cameras where this is happening, what shutter count level have you reached with each one? Have they been heavily used?

[MetteHHH]

Thanks for noticing this thread. I am reviewing your thread from four years ago for clues.

Random overexposure problem getting worse! - PentaxForums.com

Did you ever get the problem resolved?


Steve

Well the lens was still under warranty, so I sent it back to the store with a description of the problem (and a link to the thread here!) and they had it opened and cleaned for oil. It did help, at least for a while, but with continous shooting I do get overexposed shots. Also I think I have observed that the problem is worse in cold weather - but I didn't test it properly.

I thought about sending it back again, but I might not get around to it. Shipping costs, waiting for weeks... it might not be worth the trouble I think. It stops down further than it used to, at least.

[corvin]

Let's see if I can answer all of the questions:

Happens on different lenses on all three bodies. Doesn't appear to play favorites that way with lenses or combinations.

Exposure mode = AV and TAV that I've noticed so far. Can try others.

In-camera mode from two in a sequence: https://emmisoure.zenfolio.com/p104379158 (I paid for zenfolio but have yet to build anything there - ugh!) - think I've set it to be downloadable (original .jpgs)

Often occurs when panning or tracking birds/insects. Sometimes, though, when I think I'm holding still, too. Burst shots of flowers, birds, etc.

Could be a sticky blade problem. But unlikely. I've swapped out lenses among bodies. And it seems to be a body rather than a lens problem. I'll explore that further, though. (to MetteHHH)

Re 4x Kx bodies - I hate swapping lenses. And my wife and I both shoot. So I try to collect the current body that I'm shooting. And then refrain from swapping lenses so much. Mostly I shoot bees, birds, flowers, and gardens. Nothing too special about any of that.

Shutter count of one is 100k+. The other two are...I think...~20K or so. (16K on the posted .jpg. - the other is roughly similar)

I'm 99pct sure it's not an issue with lenses. I've used so many (some new) among the cameras and it does seem body specific. In fact, after the bees on the muscari, I put a lens that's had blown-out results onto the "good" body and got consistently-lit shots. I can fiddle further there.

Thanks for the replies so far. Let me know if I've missed an answer or have not been clear.

[stevebrot]

In-camera mode from two in a sequence: https://emmisoure.zenfolio.com/p104379158 (I paid for zenfolio but have yet to build anything there - ugh!) - think I've set it to be downloadable (original .jpgs)

Thanks! I downloaded both files and found no smoking gun. The body had only 16151 shutter actuations and was made in March 2014. The recorded metadata are essentially identical between the two frames. Assuming the lens iris mechanism is functioning properly (no lazy aperture)and that both are natural light phots, possible causes include:

• Change in light between start and end of shutter burst
• Fault in aperture controller mechanism or electronics
• Fault in shutter controller timing or lazy trailing curtain
• Fault in sensor or supporting electronics
• Fault in image processor

Why this should be happening with several bodies from the same owner with few reported similar issues on the K-3 is troubling.

@MetHHH, what is your camera serial number?

Note: I am not rulling out the lens.


Steve

[BigMackCam]

Thanks! I downloaded both files and found no smoking gun. The body had only 16151 shutter actuations and was made in March 2014. The recorded metadata are essentially identical between the two frames. Assuming the lens iris mechanism is functioning properly (no lazy aperture), possible causes include:

• Change in light between start and end of shutter burst
• Fault in aperture controller mechanism or electronics
• Fault in shutter controller timing or lazy trailing curtain
• Fault in sensor or supporting electronics
• Fault in image processor

Why this should be happening with several bodies from the same owner with few reported similar issues on the K-3 is troubling.

@MetHHH, what is your camera serial number?


Steve

Steve, can I ask what tool you're using to analyse EXIF data, please? I'd be interested to see what the manufacture date of my own K-3 is... thanks in advance

[stevebrot]

I'm 99pct sure it's not an issue with lenses

What happens if you do a burst with the same lens at maximum aperture?


Steve

[stevebrot]

Steve, can I ask what tool you're using to analyse EXIF data, please? I'd be interested to see what the manufacture date of my own K-3 is... thanks in advance

ExifTool


Steve

[corvin]

By that do you mean wide open, Steve? At 2.8? (I suspect so).

---------- Post added 04-23-19 at 06:34 PM ----------

Small, quick test. About 200 shots each camera.

Tried the 100mm 2.8 WR macro on a "bad" body (the one with ~16K) and got blowout at 2.8 and 11.
Moved the lens to the one "good" K-3 and got consistent light at 2.8 and 11.

Both on H igh burst, TAV mode. Spot focus, spot metering.