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08-25-2010, 04:34 AM   #91
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QuoteOriginally posted by Ryhfeed Quote
I`ve checked again and either i have a surprisingly good K7, or im not such i pixelpeeper i thougt after all. Discovered another thing though (now opening Pandoras box with a curious but vacant facial expression): If i shoot a burst of 2-3frames at any given shutter speed, and after that the SR hand symbol has lit up, the second or third fram is always (or at least in 80% of my VERY unscientific test) a tiny bit sharper than the first. (And i still percieve the first frame as sharp, the difference is subtle but easily noticable already on the cameras display.) Hmmm...I also dug out my old K10D and tried it and discovered the same thing there. Not double daring you again, but: Is this a phenomenon you (or anyone) have encountered?
I'd say the first pic is blurred because you're still moving to actuate the shutter...
Following pics are then taken once your hand has settled...

08-25-2010, 04:58 AM   #92
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QuoteOriginally posted by Class A Quote
I wouldn't be so sure that the designers knew about the problem that well.
99.9% certain they knew about shutter slap. It's an issue of severity and trade-offs. Pentax's engineers may have underestimated the severity.
08-25-2010, 05:01 AM   #93
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QuoteOriginally posted by Class A Quote
And who know how a lens-based SR system reacts to shutter-induced camera movement?
Good point. It may have been a core reasons to use lens-stabilization instead of in-body.
08-25-2010, 05:13 AM   #94
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QuoteOriginally posted by Aristophanes Quote
99.9% certain they knew about shutter slap. It's an issue of severity and trade-offs. Pentax's engineers may have underestimated the severity.
I don't follow. If they knew about the interaction between shutter slap and SR then they would have been in a position to measure the effect. How can they then underestimate the severity?
Either they accepted the compromise or they didn't know about it. No one, except insiders, can be sure (down to the tenth decimal place ) which of the two cases were the case.

08-25-2010, 05:27 AM   #95
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QuoteOriginally posted by Class A Quote
I don't follow. If they knew about the interaction between shutter slap and SR then they would have been in a position to measure the effect. How can they then underestimate the severity?
Either they accepted the compromise or they didn't know about it. No one, except insiders, can be sure (down to the tenth decimal place ) which of the two cases were the case.
Shutter and mirror slap have been around since there have been shutters and mirrors! So maybe they measured less accurately than Falk? There are many controlled situation tests that fail in the "real world" where this issue popped up almost immediately with both the K-7 and K-x (as did the 16-50 SDM failures).
08-25-2010, 05:28 AM   #96
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QuoteOriginally posted by Class A Quote
Do you know that he was one of the first in Germany to receive a K-7 for testing?
About that, I wonder if he will get the same chance with the K5?
08-25-2010, 05:43 AM   #97
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QuoteOriginally posted by Thom Hogan via Aristophanes Quote
Indeed, I’m almost certain that the camera companies know this example very well. It’s a design choice. The Olympus m4/3 cameras exhibit the same issue, probably for the same reasons. It’s a cost/performance decision.
As far as classical shutter blur is concerned, I tend to agree with Thom. However, we spent quite some time to find out that classical shutter blur cannot explain more than maybe 50% of the effect. Probably less. Classical shutter blur is small enough for the K-7. There is a yet to be fully explained magnifying effect involved and it cannot be as simple as "it's the existance of an SR apparatus" because then the K20D would show the same effect. So, the magnifying effect is avoidable and it is not a design decision.

Of course, this has all be discussed at lengths. I only mention it again because I doubt that Thom has gained a detailed enough understanding of what you were talking about to him.
08-25-2010, 06:02 AM   #98
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QuoteOriginally posted by Class A Quote
I don't follow. If they knew about the interaction between shutter slap and SR then they would have been in a position to measure the effect. How can they then underestimate the severity?
Either they accepted the compromise or they didn't know about it. No one, except insiders, can be sure (down to the tenth decimal place ) which of the two cases were the case.
QuoteOriginally posted by falconeye Quote
As far as classical shutter blur is concerned, I tend to agree with Thom. However, we spent quite some time to find out that classical shutter blur cannot explain more than maybe 50% of the effect. Probably less. Classical shutter blur is small enough for the K-7. There is a yet to be fully explained magnifying effect involved and it cannot be as simple as "it's the existance of an SR apparatus" because then the K20D would show the same effect. So, the magnifying effect is avoidable and it is not a design decision.

Of course, this has all be discussed at lengths. I only mention it again because I doubt that Thom has gained a detailed enough understanding of what you were talking about to him.
Actually, he read your article, then commented. We were discussing design and manufacturing defects and warranties.

I suspect Pentax thought they had damped or controlled the interplay between SR and shutter enough, mismeasured (or did not have the tools to measure the "magnifying effect") and did not do enough "real world" testing. By the time it became an issue, they had the choice of diverting internal resources to fixing the K-7/K-x current problem, or working the next gen to control it better, perhaps in part thanks to Falk. I believe they chose the latter as this was detailed quite late in the product cycle. OTOH, perhaps the blur falls within Pentax's acceptable norms. If that is the case, then they are out-of-sync with many of their customers. Again, it's water under the bridge as a new model is forthcoming. We'll have to see with the K-5/r. And we'll have to see if there is a potential K-7/x fix after the new cameras are out the door and resources can be diverted to addressing the issue (if possible). Sadly, quite a few overly blurry photos will be taken between now and said fix. I do think this has affected new K-7 sales.


Last edited by Aristophanes; 08-25-2010 at 06:26 AM.
08-25-2010, 06:27 AM   #99
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QuoteOriginally posted by Aristophanes Quote
Shutter and mirror slap have been around since there have been shutters and mirrors!
But the K-7 shutter-induced blur problem can only be explained in conjunction with the SR mechanism and that hasn't been around since there have been shutters and mirrors.

QuoteOriginally posted by Aristophanes Quote
So maybe they measured less accurately than Falk? There are many controlled situation tests that fail in the "real world" ...
But in this case it would not have been a concious "we can live with that"-design-decision.

I'm inclined to think that they weren't aware of the real world effect and one has to acknowledge that it took the user base a long time to identify a problem at all as well. In many circumstances other factors will create greater blur so we're not talking about an issue that makes the camera obviously unusable for certain shutter speeds.

BTW, judging from what zackspeed wrote when Falk et al. reported about the shutter-blur issue, the new cameras were already finished. Not sure whether the shutter-induced blur findings could influence the new development at all. Let's hope that the new cameras are not affected. No matter how insignificant the effect may be for many users in practice, it would still be tainting the new cameras and may prove to be harmful for sales.
08-25-2010, 06:39 AM   #100
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QuoteOriginally posted by Class A Quote
But the K-7 shutter-induced blur problem can only be explained in conjunction with the SR mechanism and that hasn't been around since there have been shutters and mirrors.


But in this case it would not have been a concious "we can live with that"-design-decision.
We don't know Pentax's parameters. We can only speculate that this is beyond theirs and Falk has illuminated the matter. It may very well be Pentax finds the blur within their acceptable norms, in which case Falk is a white paper critic trying to move that acceptable norm.

QuoteQuote:
I'm inclined to think that they weren't aware of the real world effect and one has to acknowledge that it took the user base a long time to identify a problem at all as well. In many circumstances other factors will create greater blur so we're not talking about an issue that makes the camera obviously unusable for certain shutter speeds.

BTW, judging from what zackspeed wrote when Falk et al. reported about the shutter-blur issue, the new cameras were already finished. Not sure whether the shutter-induced blur findings could influence the new development at all. Let's hope that the new cameras are not affected. No matter how insignificant the effect may be for many users in practice, it would still be tainting the new cameras and may prove to be harmful for sales.
Concerns about abnormal blur were seen on DPR almost immediately with the K-7 and K-x. Any sane manufacturer listens to consumer feedback. Some of it was very detailed right away, narrowing down the shutter speed problem within Falk's measured range. Most attributed it to the mirror, but many correctly guessed that there was an SR interaction responsible. Many were puzzled that the blur was reproducible with SR off on tripod shooting. Hence, the shutter slap conclusion. Falk empirically detailed.

I agree not addressing the issue will harm sales, and may contribute to the perception than in-body SR is less effective and more problematic than in-lens correction. I, for one, will not spend the $$ unless I see this blur issue addressed. The SS range is simply too common to have this much variation causing visibly noticeable blur.
08-25-2010, 06:59 AM   #101
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Let's hope this is fixed on the K-5.
08-25-2010, 07:44 AM   #102
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I have made some more tests later today with 1/100 and 1/800 comparisons with 17mm length. Over and over again the difference between a snapshotcamera slightly smeered/blurred picture and a TACSHARP super picture. I don`t know how to post them but believe me on my (experienced fotographer) word. Side by side comparison makes things soo obvious. Stupid that I never came to the idea to make a side by side test to see this but it did never cross my mind that my sometimes dissapointment with sharpness could have something to do with shuttertime ( shutter movement freqencies) when I look back in my Photo files it is indeed the around 1/100 sec wide angle "sweetspot" where the dissapointment took me.
08-25-2010, 04:05 PM   #103
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Here is a real life crappy comparison, shot with 16-50 at 16 mm.1/80 first and 1/800 second, f:whatever. hand held in poor lighting, jpeg, no processing except 100% crop.,
Both look pretty darn good to me, well within expectations and acceptable, given the conditions.

Cheers, Mike.

Both ISO 200, one is f: 9 and other f: 2.8
On second one, you can see NR. kicking in loosing some detail.

Last edited by Ex Finn.; 11-11-2014 at 05:51 PM.
08-26-2010, 05:10 AM   #104
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08-26-2010, 05:17 AM   #105
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As I am not very good at uploading pictures I have placed 2 same pictures in my posting above of the 1/100 sec crop 17mm with my Pentax K7. Sorry for that but I don`t want to mess around and accidently delete the whole stuff.
Picture (2) on top is as said 1/100 sec focused on screw on horizontal wooden strip at top of little litehouse in the middle and the same I did with same exposure and only seconds after the 1/100 picture with 1/800 . Amazing sharpness difference isn`t it ? I can repeat this reslut each time .
Look at the strip of wood on top with the screw in the middle. the amount of details in the 1/800 picture is amzing but completely blurred out at 1/100 !
THIS IS SHUTTER BLUR FROM MY PENTAX K7 ! I don`t want this so I want PENTAX to act fast !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I challenge all nikon and Canon owners to do the same sort of test and see if they manage to create this ridiculous differences with their camera`s.
I am a PENTAX lover from the first hour but this is killing my love affair soon I am afraid.

Last edited by bjan; 08-26-2010 at 05:28 AM.
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