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12-02-2010, 06:01 AM   #31
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QuoteOriginally posted by andre-mz5 Quote
I would be interested to see if this type of blur is also noticed on SONY DSLR which use in-body SR too. Thus it is may be caused by the concept of using in-body SR. For verification these test should also be executed with a 7D or D7000 which should show NO BLUR at all since they do not use in-body SR.
I guess you never bothered reading Falk`s white paper on this issue, did you?

12-02-2010, 06:09 AM   #32
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This is NOT inevitable with a "floating sensor"

Those of you who think that this effect is the inevitable result of Pentax's approach to SR must not have read all of Falk's reports on this issue. The effect is close to zero on the K20D. This was shown in his earlier reports, and is repeated in his report on the K-5:

"The absolute magnitude of the effect sits halfway in between a K20D which has almost no measurable effect and a K-7 which exhibits an effect large enough to make some people notice in their work." (from Falk Lumo: LumoLabs: Pentax K-5 shutter, emphasis added.)

Something was changed in the K-7 design that introduced this problem. It was not a problem with the K20D. Apparently Pentax hasn't yet figured out what went wrong. But it certainly is not as simple as a "floating sensor", or the K20D would also have had the problem.

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12-02-2010, 09:11 AM   #33
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QuoteOriginally posted by Michaelina2 Quote
(emphasis added)
I bought up the question of sample variation because in my day job of warranty analysis it is VERY important. It is the difference between a fleetwide defect (similar to a automobile mfg recall) and a minor reoccurring glitch. The problem is sample variation isn't all that easy to verify. That said I trust Falk's judgement on this. There are certain engneering functions that aren't subject to sample variation. And I know little enough of optics and optical engineering to make any kind of judgement. A DSLR camera body is somewhat different from a subway car.

NaCl(if it was about dynamic braking maybe I'd give some input)H2O
12-02-2010, 09:17 AM   #34
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QuoteOriginally posted by falconeye Quote
Our K-7 study didn't indicate a significant effect of sample variation. But we never exactly measured it. So, I'm not sure how large the sample variation can be for the K-5. It's more a feeling I have that the difference is real rather than sample variation.
Thanks Falk, sort of what I expected. However I know very little about optics and optical engineering, I'll leave that to youse guys.

NaCl(subway cars aren't much like cameras)H2O

12-02-2010, 09:57 AM   #35
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QuoteOriginally posted by Abstract Quote
"In these cases, we highly recommend to shoot at 1/25s (or slower) and to enable shake reduction as it is highly efficient at such exposure speeds. The images will be sharper than at 1/100s!"
That seems insane.
QuoteOriginally posted by ogl Quote
It sounds insane for me too.
The above are quotes copy-pasted from the K-7 report.

I do not appreciate such out of contect quotes.

For the K-7, the above statement is correct for a certain range of focal lengths. Nothing insane.

Please, don't quote from the K-7 documents if it isn't applicable here in the K-5 context. Apply some sanity.
12-02-2010, 10:04 AM   #36
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I understand ogl is disappointed. What else?

But otherwise, please don't blow this out of proportion. We're talking about a subpixel phenomenon. I don't think this affects day to day photography anymore. And without the K-7 precedent, nobody would have looked into this and for other makes, nobody actually does

What I found is what we would have expected:

The problem is mitigated enough for people not to take notice anymore. But not entirely eliminated (wasn't expected either in light of similialities with the K-7).


So, my report is basically a confirmation of what everybody was thinking already. It shouldn't be worth a big discussion but I find it reassuring to know the hard facts now.
12-02-2010, 10:19 AM   #37
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Nice to read that Pentax made good improvements.
12-02-2010, 10:29 AM   #38
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QuoteOriginally posted by Abstract Quote
Just a random thought that popped into my head, do we really need shake reduction at a shutter of 1/100 and above? Am I missing something cause I always felt that images came out clear at anything above this...I always had trouble at 1/60 and below. I don't know, trying to figure all this out.
I think this is a good point. Why not ask for a FW update to allow selecting the shutter speed where SR should join in??

12-02-2010, 10:32 AM   #39
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i think falk has explained several times that sr has nothing to do with it, this is shutter induced blur, and it can happen just as well on film cameras. i might be wrong, but i'd suggest you read falk's thorough article before starting to "process" his statements.
12-02-2010, 10:51 AM   #40
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1. does anyone have an example of what this would look like on a 100% crop?

2. would the effect be less if you use the mirror lock mode?

Last edited by PixleFish; 12-02-2010 at 11:02 AM.
12-02-2010, 11:05 AM   #41
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I have the K-7 and have not noticed any shutter blur effect until recently (very slightly and hardly noticable) when I used flash. Does that blur occur only on certain range of shutter speed and also focal length used? Thanks....
12-02-2010, 11:15 AM   #42
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As far as I know, flash disables SR...

edit: but as said above, maybe SR isn't the issue. I dunno.
12-02-2010, 11:39 AM   #43
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QuoteOriginally posted by kittykat46 Quote
You do need shake reduction for 1/100 secs shutter speed when you are using a 300mm lens. I have taken a few shots with the K-5 and the DA 55-300mm @ 300mm, and I haven't seen any blurring.
Let's introduce some sanity into the discussion. Consider the relative impacts of miniscule shutter blur shooting with SR and camera shake shooting without SR under the conditions described above. It should not be hard to see that the former is inconsequential, while the latter is not. Remember, folks, the shutter blur effect that Falk has measured for the K-5 is visible only with the most careful inspection at ridiculous enlargement sizes. It has little or no impact on real word photography. I think that Falk has been quite clear about this in interpreting his own work. Listen to the man, and stop obsessing about trivialities.

Rob
12-02-2010, 12:17 PM   #44
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QuoteOriginally posted by robgo2 Quote
Let's introduce some sanity into the discussion. Consider the relative impacts of miniscule shutter blur shooting with SR and camera shake shooting without SR under the conditions described above. It should not be hard to see that the former is inconsequential, while the latter is not. Remember, folks, the shutter blur effect that Falk has measured for the K-5 is visible only with the most careful inspection at ridiculous enlargement sizes. It has little or no impact on real word photography. I think that Falk has been quite clear about this in interpreting his own work. Listen to the man, and stop obsessing about trivialities.
Amen !
12-02-2010, 12:52 PM   #45
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QuoteOriginally posted by robgo2 Quote
Let's introduce some sanity into the discussion. Consider the relative impacts of miniscule shutter blur shooting with SR and camera shake shooting without SR under the conditions described above. It should not be hard to see that the former is inconsequential, while the latter is not. Remember, folks, the shutter blur effect that Falk has measured for the K-5 is visible only with the most careful inspection at ridiculous enlargement sizes. It has little or no impact on real word photography. I think that Falk has been quite clear about this in interpreting his own work. Listen to the man, and stop obsessing about trivialities.

Rob

+1, and well said.
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