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07-21-2010, 04:49 PM   #1
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Shutter induced blur with the Pentax K-7 camera

Blur that occurs at about 1/80 up to 1/200 is a K7 trait that a considerable number of K7 users have experienced. Three researchers have executed a thorough examination and published their findings at

LumoLabs -- Shutter-induced blur for Pentax K-7

or on their blog at:

Falk Lumo: LumoLabs: Shutter-induced blur with an SLR camera

This effect has caused me some distress as it seems not only to come with ww lenses as the paper suggests but also with other lightweight lenses, such as DA70 in this example at 1/160 (f6.3).

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Last edited by Marignac; 07-21-2010 at 05:01 PM.
07-21-2010, 05:05 PM   #2
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The results are republished here, too, by the author.

https://www.pentaxforums.com/forums/pentax-news-rumors/108199-lumolabs-shutte...-7-camera.html
07-21-2010, 09:45 PM   #3
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I've noticed this with various cameras, though generally at somewhat slower speeds. The Super Program film camera for example, shook so badly at around 1/8-1/15 second that it took a 15 pound wood tripod to hold it steady with a longish lens.
07-21-2010, 10:54 PM   #4
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I've had a few similarly spoiled pictures from my K-7, with unexplainable blur where the shutter speed was well above the limit of the SR capability.
I suppose this explains those shots.

It seems to be a rare, unusual event to me , as I'm still very happy with the output from the camera.
It does worry me it might spoil THAT shot just at THAT priceless, unrepeatable moment.

07-22-2010, 06:39 AM   #5
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a couple of questions and comments

has anyone looked to see if this is a SR issue only or does it occurr with SR turned off. specifically is the vibration causing the SR to respond or causing the sensor to move ?

also, with respect to tripod use, there has always been a need to stabalize tripods with weight suspended from the tripod because of the high frequency vibrations possible in the tripod itself.
07-22-2010, 06:55 AM   #6
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QuoteOriginally posted by Lowell Goudge Quote
a couple of questions and comments

has anyone looked to see if this is a SR issue only or does it occurr with SR turned off. specifically is the vibration causing the SR to respond or causing the sensor to move ?

also, with respect to tripod use, there has always been a need to stabalize tripods with weight suspended from the tripod because of the high frequency vibrations possible in the tripod itself.
True about the tripods. When I was still using metal legged tripods I found that a bungee cord wrapped around the legs at the first lock did an admirable job of damping vibration.
What I found with the Super Program was that it was smooth from high speed down to 1/60th. At 1/30 some cameras induced shake was noted, at 1/15 it was quite a bit worse, topping out at 1/8, and by 1/4 it has pretty much either gone or masked by the long exposure time.
My test beds for this was a Manfrotto 055 (which is a pretty light tripod for a metal one), and 028 (029? I can never keep straight which is the tripod, which is the head), which is quite a heavy tripod, and a Zone VI standard.
None of my 3 LX bodies showed this tendency.
07-22-2010, 07:36 AM   #7
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I noticed the same effect with K-x a short while ago. I got sometimes blurry pictures with 1/60-1/200 shutter speeds and wide angle lenses, so I did some tests and got similar conclusions as LumoLabs, but I wasn't sure if it was caused by shutter although it seemed so. Thanks to LumoLabs people for doing this research. Before this research I though that my camera could be broken.

Because of this blur effect I have been avoiding those shutter speeds with 18-30 mm focal lengths and have gotten much less blurry pictures.
07-22-2010, 09:43 AM   #8
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All this research is also something of an advertisement for deconvolution software. Like FocusMagic, which I recommend any camera user have in their PP toolbox.

07-22-2010, 06:11 PM   #9
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QuoteOriginally posted by rawr Quote
All this research is also something of an advertisement for deconvolution software. Like FocusMagic, which I recommend any camera user have in their PP toolbox.
Yes, Focus Magic works like *Magic. I'm still trying to figure out the maths of how it does it - some of it I can understand, but not the overall process.

One very good feature, even if you choose not to edit the photo, is that Focus Magic does an objective calculation of how "sharp" your photo is overall. It won't "know", of course, if you focused on the wrong object, but overall picture blur is quantifiable.

That comes back to my original point. The vast majority of my K-7 photos are as sharp as anything coming from other brand cameras, confirmed with Focus Magic.
The rest is lens and user (me) dependent.

I've had very few unexplainable blurred photos.

So I appreciate the excellent work Falk has done, I hope Pentax works to solve it, but its a minor issue to me, and I still very much trust the K-7 as a photographic tool.
07-23-2010, 11:07 AM   #10
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I have recently purchased a K-7 and after reading the shutter blur posts I frantically tested shutter speeds from 1/45-1/250 with both the 18-55 WR lens as a lightweight option and my Sigma 10-20 using both a cheap wobbly tabletop tripod or handheld.

While far from a rigorous or scientific testing method, I can detect no shutter blur from 1/60 to 1/25, at least not to the point I can see it at %100 view. I'm not saying it's not there, it's just not noticeable to me.

Perhaps I got lucky or it has not manifested itself yet, or the camera's or shutter's manufacturing run did not have an issue. I am certainly sorry it is causing problems for some people.

I'm using the 1.03 firmware.
Eric
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