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12-03-2010, 04:33 PM   #16
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QuoteOriginally posted by creampuff Quote
Imo the shutter blur bunkum is just more pseudo-scientific crap. Unfortunately pseudo-scientific tests is a fav topic for some and the more it gets circulated, the more it takes a life of its own, needlessly scaring sensible people witless. Btw, I have never encountered any supposed issue with my K-5 or my previous K-7 for that matter.
I welcome this thread.

My shutter blur evaluation isn't pseudo-scientific or crap. But despite the fact that I said as clear as possible that the entire effect is a subpixel effect for the K-5 people won't notice in their work, people won't easily believe this. Of course, I wouldn't have done the work for the K-5 if the K-7 wouldn't have required it.

Also, I think I succeded to communicate that the K-5 has no "problem" here. I don't see a forum mill, not even over there at DPR where I didn't post on purpose.

Moreover, this thread is another good effort.

Nevertheless, bashing of my work should go in "my" thread. This thread would be better used for image examples.

In my study, I show an image where the effect is strong enough to see it with the naked eye, i.e. where the effect exceeds a pixel. Such images are the exception though and I don't expect to see them here in this thread.

So, let the images speak and rightly so

12-03-2010, 04:52 PM   #17
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Picture sharpness is overrated anyway.




Falk, thank you for your excellent investigations! I am very happy to see the K5 results.

My best regards,
Bob
12-03-2010, 05:05 PM   #18
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I'm old.
My tremor is worse than 2pixels worth of blur.

But my K-7 and K-5 fix it and make my photos look good (at least to me anyway).
12-03-2010, 09:03 PM   #19
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Testing is always a great idea and a lot of work. Kudos to falconeye or anyone else that spends the time to do an in depth study. Heres another addition DA40 at iso400, 1/80, f4


Last edited by ivoire; 05-05-2011 at 06:04 AM.
12-04-2010, 02:37 PM   #20
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Shutter blurr

GimbaL and whoever is interested:
LumoLabs tested the K-7. When did they test the K-5? I found that there is a difference between the K-7 and the K-5 when using SR on a tripod. The K-7 needs to have SR disabled, even with FW 1.10, otherwise you add blurr to shots taken at under 1/180 speed. It also has real problems with LV on a tripod when SR is active. Not so the K-5. I do get actually sharper pictures in LV below 1/100 with the K-5 and telephoto lenses up to 500mm than in VF mode. I thought this was due to mirror slap. Now I read the LumoLab acrticle and they claim the mirror movement has nothing to do with it. I think it has for the K-5 and that it is 'masked' by a stronger shutter effect in the K-7, perhaps. I didn't do a scientific test, as LumoLabs did, but I can provide photos if anyone is interested. Bottom line, Pentax must have fixed something to reduce the shutter blurr in the K-5, but the 'mirror slap effect ' is now obvious at shutter speeds below 1/100, even with SR on, IMHO.
12-04-2010, 05:30 PM   #21
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QuoteOriginally posted by EyeofmyPentax Quote
but the 'mirror slap effect ' is now obvious at shutter speeds below 1/100, even with SR on, IMHO.
My LumoLabs article about the K-5 is discussed in a sibling thread. AFAIK, this thread (you are reading now and where you posted) is dedicated to photos.

K-5 mirror slap is measurable on a weak enough tripod. But not free hand. Further details via the other thread, please.
12-04-2010, 08:58 PM   #22
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QuoteOriginally posted by falconeye Quote
I welcome this thread.

My shutter blur evaluation isn't pseudo-scientific or crap. But despite the fact that I said as clear as possible that the entire effect is a subpixel effect for the K-5 people won't notice in their work, people won't easily believe this. Of course, I wouldn't have done the work for the K-5 if the K-7 wouldn't have required it.
Falk, in my statistical knowledge I believe your tests weakness is not the method you are using but is the number of the sample size, statistically n:1 does not represent the universe (in statistical terms universe means the number of the K-7 or K-5 ever produced). With a sample is size of 1 you are assuming that all of the produced cameras are behaving same as the ones you are tested., which might not be scientific.. You have to perform an a-priori power analysis and calculate the sample size to report the mean difference with a precision (for 95.0% confidence level). Then you have to test minimum enough number of cameras to be able to report shutter shake levels of a certain camera model(s).

For instance a Power analysis sample


unless explaining to us (at least to me) why would you expect all K-7's or K-5 will behave (in the shutter shake levels of course) exactly same as you are tested.

I have to mention that I would like to thank you for your tests here once more.
12-05-2010, 04:11 AM   #23
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QuoteOriginally posted by cbaytan Quote
unless explaining to us (at least to me) why would you expect all K-7's or K-5 will behave (in the shutter shake levels of course) exactly same as you are tested.
Wrong thread (again).
Moreover, I commented about sample variation in my study and the appropriate thread, already.

QuoteOriginally posted by cbaytan Quote
I have to mention that I would like to thank you for your tests here once more.
You have a strange way to say thank you

12-05-2010, 06:30 AM   #24
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QuoteOriginally posted by falconeye Quote
Wrong thread (again).
Moreover, I commented about sample variation in my study and the appropriate thread, already.
Why wrong thread Falk? I've quoted you. In fact I am not aware the thread you are mentioning, would you point us please?
12-05-2010, 07:13 AM   #25
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QuoteOriginally posted by cbaytan Quote
Why wrong thread Falk? I've quoted you. In fact I am not aware the thread you are mentioning, would you point us please?
https://www.pentaxforums.com/forums/pentax-k-5-forum/124523-lumolabs-shutter-...-5-camera.html

It's on the same page of thread listings as this one, has 4x #replies and a clear title. Is it really this difficult to find?

Anyway, I may post pictures at shutter blur speed here but otherwise won't respond anymore.
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