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Thanks for the explanation, good to know.
However, if this was the reason, the images should show some sort of motion blur instead, I guess?
-- Markus
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[quote name='mst' timestamp='1294842471' post='5450']
Thanks for the explanation, good to know.
However, if this was the reason, the images should show some sort of motion blur instead, I guess?
-- Markus
[/quote]
Any chance of seeing a sample of what it looks like?
[quote name='Ayoh' timestamp='1294839641' post='5446']
Could it be on account of mass change of the sensor and SR assembly due to replacement cover glass? The dynamic response of the SR system could be affected by a mass change. Did the blur occur at all shutter speeds?
[/quote]
Hmmm, but shouldn´t this be the same problem for all Pentax cameras?
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[quote name='mst' timestamp='1294839971' post='5448']
SR is switched off in the lab, the shadows remained, though.
-- Markus
[/quote]
They exchanged their replacement glass with the original AA filter and the image was fine again. Really a mystery.
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Possibly due to a difference in mass as stipulated...
[quote name='Klaus' timestamp='1294850815' post='5455']
They exchanged their replacement glass with the original AA filter and the image was fine again. Really a mystery.
[/quote]
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[quote name='Ayoh' timestamp='1294869922' post='5458']
Possibly due to a difference in mass as stipulated...
[/quote]
If so the problem would have showed up in tele shots as well. The effect decreased towards longer focal lengths.
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Not necessarily as it is difficult to know with certainty how a mass change would affect the response of the SR system throughout its operating range.
The only alternative I can think of would be to attribute the effect to some mysterious optical interaction of the replacement filter glass with:
- the sensor cover glass and/or
- IR cut filter
- dust filter
This seems unlikely however as the effect would probably not be exclusive to the k-5.
The SR system seems the most likely culprit. A fix could be to add/remove weight to the sensor stage to maintain the original specification, or more crudely, rigidly fix the platform using screws and permanently disable SR.
[quote name='Klaus' timestamp='1294876817' post='5459']
If so the problem would have showed up in tele shots as well. The effect decreased towards longer focal lengths.
[/quote]
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[quote name='Klaus' timestamp='1294876817' post='5459']
If so the problem would have showed up in tele shots as well. The effect decreased towards longer focal lengths.
[/quote]
We are not privy to the shots taken. So, we can only take guesses. But usually, wider angle shots are taken with longer exposure times than tele stuff. We already know from the K7 that the SR system gives a blur problem at certain low-ish shutter speeds due to mirror slap moving the sensor.
So if that a difference between the taken wider angle shots and the tele shots, that will explain it partly.
Also, it could be that the longer lenses are more heavy, or the camera is held differently, which might absorb more energy from the mirror slap, making the SR assembly move less with the tele shots.
Hello,
It is indeed possible that the shutter blur is compensated by the SR system. If you know the disturbances of the shutter actuation (measurable), then you can add a signal to the feedback system to compensate therefor. If the mass of the sensor is reduced now (or only the centre of gravity has changed a little or all the moments of inertia are a little bit different), then the compensation signal is too strong or even totally inappropriate, considering that SR accounts for tilting and rotation as well, as far as I know.
Maybe you can ask Pentax for a new calibration of the SR system.
coon
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