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12-17-2009, 03:20 PM   #1
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Sensor shift during "long" exposures

I noticed this several months ago during a DC trip, but ignored it since it only happened a couple times and I couldn't find anything online about it, but now it's getting annoying. I was in the living room testing out my new flash and set the camera for a 10sec exposure. I had the camera sitting on the desk and clicked the shutter. I heard the sensor move and felt the camera jostle a little (imgp8908.jpg). I attributed it to the shake reduction being off, so I turned it on, and it was significantly worse (imgp8909.jpg).

Has anyone seen this before?? If so, what could be causing it?? Is there a fix for it?? I'm only at firmware 1.00, but I've only seen that 1.01 allows for larger SD cards.

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12-17-2009, 03:35 PM   #2
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SR on or off?
12-17-2009, 03:38 PM   #3
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I thought of something similar but different than this. When you click the shutter button, the mirror flips and I guess it causes the sensor to move or something.

https://www.pentaxforums.com/forums/pentax-dslr-discussion/83063-k-7-horizon-correction.html
12-17-2009, 03:41 PM   #4
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QuoteOriginally posted by ryan s Quote
SR on or off?
Both, the first image is with it OFF, the second (much worse) is with it on.

QuoteOriginally posted by LeDave Quote
I thought of something similar but different than this. When you click the shutter button, the mirror flips and I guess it causes the sensor to move or something.

https://www.pentaxforums.com/forums/pentax-dslr-discussion/83063-k-7-horizon-correction.html
This happens well after the mirror flips up.

i should mention, this isn't limited to a 10sec exposure, it seems to happen on anything over 4sec. Just tested it, and on a 15 sec exposure, it happened 4 times.


Last edited by eclipsed450; 12-17-2009 at 03:47 PM.
12-17-2009, 03:53 PM   #5
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This is what tripods are for.
12-17-2009, 03:58 PM   #6
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QuoteOriginally posted by Marc Sabatella Quote
This is what tripods are for.
it does it on a tripod as well, manual or auto focus, sr on or off, any of my lenses, eneloops or energizers, flash or no flash...i'm seriously at a loss guys...

Last edited by eclipsed450; 12-17-2009 at 04:07 PM.
12-17-2009, 04:10 PM   #7
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Haven't heard of this - maybe there is something wrong with yours. Many people do long exposures with tripods..
12-17-2009, 09:06 PM   #8
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Did you have mirror lock up set for the long exposures? Even with SR off, this should be enabled to minimise mirror shake, and especially with a a tripod etc.

On my K200D that's done with the self timer on 2sec - you hear the mirror flick up when the countdown starts, then the shutter.

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12-18-2009, 03:49 AM   #9
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QuoteOriginally posted by eclipsed450 Quote
it does it on a tripod as well, manual or auto focus, sr on or off, any of my lenses, eneloops or energizers, flash or no flash...i'm seriously at a loss guys...
I often take longer low-light exposures of 10 seconds up to 5 minutes.
I haven't experienced it before, even without using the mirror-up function.

There's a risk of camera movement if I press the shutter directly - this can be avoided by using a remote trigger or the 2-second delay function. Other than that, no problems at all.
12-18-2009, 07:36 AM   #10
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That's bizzare. I don't know what camera you are using so I'm assuming something with SR and sensor cleaning capability. When I was reading this I thought that:

1. Camera movement. BUT AS OP STATED, the camera sat on the desk so essentially it's similar as sitting on a tripod.

2. Environment movement. IDK, maybe you live next to a train and the train was going by. But this is so unlikely.

3. Sensor movement. This could be:
a. SR got activated regardless if you turned it on or off. But then SR does not have that much movement.

b. Sensor cleaning got kicked in some how that move the sensor filter. This movement (from my experience with the K-x) is strong enough to jostle the camera a bit. That explains the crazy blur with SR off where the vibration from the sensor cleaning motor shakes the camera a bit. When the SR on, the SR tries to compensate for the vibration and somehow caused the intense shake (harmonic perhaps?).


I'm leaning toward 3b. That would indicate either corruption in your firmware (memory chips get corrupted sometimes), or something shortwired inside. Sorry man, but either way it's going to have to go to the expert repairman or Pentax.
12-18-2009, 11:44 AM   #11
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QuoteOriginally posted by eclipsed450 Quote
it does it on a tripod as well
Yes, but if the tripod is worth the money, it will hold the camera steady despite whatever tiny amount of vibration might be occurring normally. Although of course, if your camera is defective and is actually having abnormal movement, that's another matter. No way for us to know that, really.
12-18-2009, 12:51 PM   #12
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QuoteOriginally posted by pentaxpup Quote
That's bizzare. I don't know what camera you are using so I'm assuming something with SR and sensor cleaning capability. When I was reading this I thought that:

3. Sensor movement. This could be:
b. Sensor cleaning got kicked in some how that move the sensor filter. This movement (from my experience with the K-x) is strong enough to jostle the camera a bit. That explains the crazy blur with SR off where the vibration from the sensor cleaning motor shakes the camera a bit. When the SR on, the SR tries to compensate for the vibration and somehow caused the intense shake (harmonic perhaps?).


I'm leaning toward 3b. That would indicate either corruption in your firmware (memory chips get corrupted sometimes), or something shortwired inside. Sorry man, but either way it's going to have to go to the expert repairman or Pentax.
That's about what it feels and sounds like, although not as quick and not as jostling as the sensor cleaning, but there's definately a shift of sorts - and as you said, it's not that same humming/buzzing that SR makes when a the camera moves when SR is on. i've asked pentax and they (the 2 techs i talked to) hadn't heard of the problem i described and they suggested sending it in :-( for those that have had to send their baby to the shop, what can i be looking at for a ballpark cost seeing that i'm out of warranty??? if it needs to be fixed (hardware or software) and its significant, i'd rather hold off and put that money into a new body since this one already has ~20k accuations
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