LumoLabs: Shutter induced blur with the Pentax K-7 camera

frank · 08-26-2010, 03:25 PM

Is this a RUMOR or NEWS?

Wonder if this thread should be moved to DSLR subforum instead of staying here

bjan · 08-26-2010, 04:00 PM

Falk, I did not change the focus distance and the shote where by pressing the shutter button manually with care whilst the camera was on a stable table on a bean bag. I assume that 1/100 should create very blurr free pics this way right. I will do some more testing like you propose and try to come back with the results. For me however the "smeering " look of some of my pictures that I all find around this 1/100 area in my collection are due to the phenomen found in my (simple) test . It would be nice if I could find an other higher standard camera to make a comparison. It is not sais ofcourse that e.g a Nikon d300 will not act simillar with any given shuttertime/ frequency. what about digital shutters ?

falconeye · 08-26-2010, 04:38 PM

Originally posted by bjan

Falk, I did not change the focus distance and the shote where by pressing the shutter button manually with care whilst the camera was on a stable table on a bean bag

bjan, that should be ok if this is what you mean: you focussed the camera prior to the first shot and then switched autofocus off. Repeated trigger presses of even a static subject would move the focus. Some testers even tape the focus ring to make sure the focus stays fixed (not required with Pentax as it has no "fly-by-wire" focus).

Originally posted by bjan

I assume that 1/100 should create very blurr free pics this way right.

Yes, but it's not 100% safe. We first ran a test that free-hand and a special kind of tripod combined with a remote trigger and MLU yielded the same results. Our tripod was similiar to a bean bag but different (described in the Image Understanding Paper).

Your bean bag could have elastic behaviour and you could "catch" a movement of the bag bouncing back a few µm when you release the trigger with your digit. If you want to be on the safe side, activate Lifeview and use a remote trigger (or the timer).

As a general remark: handheld can beat weak tripods when used w/o MLU or remote trigger/timer. This is because the mirror or trigger action can excite a vibration which is poorly dampened. The human arm is much better dampened. This is why I asked if you used a remote trigger and mirror lockup. Manual focus, remote trigger/timer and mirror lockup/LV are required before one can draw conclusions from your test. I don't say the result would be any different. Because actually, I cannot know.

falconeye · 08-26-2010, 04:48 PM

Originally posted by frank

Is this a RUMOR or NEWS?

Wonder if this thread should be moved to DSLR subforum instead of staying here

It was News when the paper appeared on falklumo.com/lumolabs. Of course, it's no News anymore (except if there are new developments to report about like the effect of the recent firmware update).

Maybe, others have an opinion if now another section would be better suited? I am undecided because theoretically, any thread in this section would have to be moved off section when it is no longer new or rumor; but actually never is.

bjan · 08-26-2010, 04:55 PM

Thanks Falk for your extensive and polite replies. I will do some more testing including your recommendations. However I do not see anyhow why I repeatedly do not get any "pinsharp" shots with 17mm at 1/100 and a always "pinsharp" shot at 1/850 with a camera that has SR used by an experienced steady arm and hand . We will sees what my future tests will bring and I will keep you posted. By the way I do still LOVE my K7 . But... a little dent in our loveaffair. A bit more open for flirting .

**Ex Finn.** · 08-26-2010, 05:07 PM

It must be raining where you all live

.

Cheers, Mike.

falconeye · 08-26-2010, 05:09 PM

Originally posted by bjan

A bit more open for flirting .

Let's hope that Pentax at least still believes in and strives for life-long love

Originally posted by Ex Finn.

It must be raining where you all live

.

Don't know, it's utterly dark

**Ex Finn.** · 08-26-2010, 05:27 PM

Originally posted by falconeye

Let's hope that Pentax at least still believes in and strives for life-long love

Don't know, it's utterly dark

Stick around, in couple hours it will be daylight again

.

dlacouture · 08-27-2010, 01:18 AM

Originally posted by bjan

Thanks Falk for your extensive and polite replies. I will do some more testing including your recommendations. However I do not see anyhow why I repeatedly do not get any "pinsharp" shots with 17mm at 1/100 and a always "pinsharp" shot at 1/850 with a camera that has SR used by an experienced steady arm and hand . We will sees what my future tests will bring and I will keep you posted. By the way I do still LOVE my K7 . But... a little dent in our loveaffair. A bit more open for flirting .

And try also at 1/10 or 1/20, you should get sharp pics again...

bjan · 08-27-2010, 02:42 AM

Yeah.. and with 1 minute exposure on a tripod with no moving subjects around things should be quit sharp as well !
I JUST DON`T WANT A CAMERA THAT I HAVE TO WORK MY AROUND A 1/80 OR 1/100 SHUTTERTIME WITH

axl · 08-27-2010, 02:54 AM

I apologize but I didn't go though all of the pages, but does K-x have the same/similar issue?

alessandro63 · 08-27-2010, 04:15 AM

Originally posted by falconeye

Some testers even tape the focus ring to make sure the focus stays fixed (not required with Pentax as it has no "fly-by-wire" focus).

In Pentax cameras, as in any other DSLR, you can just decouple the focusing from the shutter button, really no need to tape anything nor to switch to manual focusing.
And of course, if pressing manually, much better to use delayed shutter.

What's impressive is the quantity of variables one must keep in account to try to verify if this issue exists: what do you think is the real incidence of this problem in real life shots? I mean: not detracting anything from your research, it appears that the chance to have a blurred shot caused by the shutter is a very very secondary one, cause it's impossible to eliminate the sum of all the other causes, that appear to be of greater amplitude.

Cheers
Alessandro

falconeye · 08-27-2010, 04:50 AM

Originally posted by alessandro63

In Pentax cameras, as in any other DSLR, you can just decouple the focusing from the shutter button, really no need to tape anything nor to switch to manual focusing.

Yes, or one uses the AF button to disable focus when pressing the shutter

What I meant was some camera makes where mounting a lens to a body may change its focus (during protocol initialization) even if all settings are manual. And testers sometimes have to switch lenses within a series and so some tape the lens.

Originally posted by alessandro63

What's impressive is the quantity of variables one must keep in account to try to verify if this issue exists: what do you think is the real incidence of this problem in real life shots?

Alessandro,

your point is valid to a point. We wrote in the Understanding Image Sharpness Paper about. All the factors which add to blur ...

But the problem is relevant in real life nevertheless. I wouldn't say it is the #1 cause for blurred images which is why I can live with that. But make a thought experiment: Assume you have 4 causes each having a 50% chance to blur an image (like defocus, lens softness, motion blur, shutter blur -- simplified model for our thought experiment!). Then the chance for an unblurred image is 6% only. Which isn't that unrealistic by the way. Tack-sharp images are the exception, not the rule (at least in demanding rather than tourist-snapshot situations). If you can then eliminate one reason for blur, the chance for an unblurred image raises to 12%. Twice as many tack-sharp images.

So, even though the single cause is largely dominated by the other causes for blur, it still makes a difference. Reasoning like this can be counterintuitive sometimes.

ihasa · 09-15-2010, 02:42 PM

Debating with myself whether to send my K-7 back. I have managed to replicated the shutter blur effect and while yeah, it's work-around-able, avoiding 1/80-1/100 with wide angle lenses is not ideal. That shutter speed corresponds to f8-f11 apertures in typical cloudy weather at 100ISO. This is the kind of thing I could forgive a cheap body like the K-x, but not a super-expensive camera like the K-7. Another thing which occurs to me is that the K-x is more flexible at getting round this problem (if it also suffers from it) because you don't have to worry so much about bumping up the ISO.

On the other hand, I'm liking most other aspects of the K-7.

I hope Pentax had this issue in their minds when they designed the K-5!

cfraz · 09-15-2010, 04:55 PM

Quote:

Maybe, others have an opinion if now another section would be better suited? I am undecided because theoretically, any thread in this section would have to be moved off section when it is no longer new or rumor; but actually never is.

The news was that you did some experiments and wrote up the results. The content has significance beyond the news item that may be important in discussions of future (and past!) generations of DSLR's, so I think the discussion rightly belongs in DSLR section. Maybe having the main discussion in DSLR with a post in News with a pointer to the main discussion thread is best. Anyway, that would be my vote should you do some work on, say the K5 or K-r (hint hint).

08-26-2010, 05:07 PM	#126
Ex Finn. Site Supporter Join Date: Nov 2007 Location: Southern Maryland. Espoo. Kouvola. Photos: Gallery \| Albums Posts: 7,975	It must be raining where you all live. Cheers, Mike.

08-26-2010, 05:09 PM	#127
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Originally posted by bjan A bit more open for flirting . Let's hope that Pentax at least still believes in and strives for life-long love Originally posted by Ex Finn. It must be raining where you all live. Don't know, it's utterly dark

08-26-2010, 05:27 PM	#128
Ex Finn. Site Supporter Join Date: Nov 2007 Location: Southern Maryland. Espoo. Kouvola. Photos: Gallery \| Albums Posts: 7,975	Originally posted by falconeye Let's hope that Pentax at least still believes in and strives for life-long love Don't know, it's utterly dark Stick around, in couple hours it will be daylight again.

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08-26-2010, 03:25 PM	#121
frank Veteran Member Join Date: Nov 2006 Location: Singapore Photos: Gallery Posts: 3,202	Is this a RUMOR or NEWS? Wonder if this thread should be moved to DSLR subforum instead of staying here

08-26-2010, 04:00 PM	#122
bjan Senior Member Join Date: Feb 2010 Posts: 116	Falk, I did not change the focus distance and the shote where by pressing the shutter button manually with care whilst the camera was on a stable table on a bean bag. I assume that 1/100 should create very blurr free pics this way right. I will do some more testing like you propose and try to come back with the results. For me however the "smeering " look of some of my pictures that I all find around this 1/100 area in my collection are due to the phenomen found in my (simple) test . It would be nice if I could find an other higher standard camera to make a comparison. It is not sais ofcourse that e.g a Nikon d300 will not act simillar with any given shuttertime/ frequency. what about digital shutters ?

08-26-2010, 04:38 PM	#123
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Originally posted by bjan Falk, I did not change the focus distance and the shote where by pressing the shutter button manually with care whilst the camera was on a stable table on a bean bag bjan, that should be ok if this is what you mean: you focussed the camera prior to the first shot and then switched autofocus off. Repeated trigger presses of even a static subject would move the focus. Some testers even tape the focus ring to make sure the focus stays fixed (not required with Pentax as it has no "fly-by-wire" focus). Originally posted by bjan I assume that 1/100 should create very blurr free pics this way right. Yes, but it's not 100% safe. We first ran a test that free-hand and a special kind of tripod combined with a remote trigger and MLU yielded the same results. Our tripod was similiar to a bean bag but different (described in the Image Understanding Paper). Your bean bag could have elastic behaviour and you could "catch" a movement of the bag bouncing back a few µm when you release the trigger with your digit. If you want to be on the safe side, activate Lifeview and use a remote trigger (or the timer). As a general remark: handheld can beat weak tripods when used w/o MLU or remote trigger/timer. This is because the mirror or trigger action can excite a vibration which is poorly dampened. The human arm is much better dampened. This is why I asked if you used a remote trigger and mirror lockup. Manual focus, remote trigger/timer and mirror lockup/LV are required before one can draw conclusions from your test. I don't say the result would be any different. Because actually, I cannot know.

08-26-2010, 04:48 PM	#124
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Originally posted by frank Is this a RUMOR or NEWS? Wonder if this thread should be moved to DSLR subforum instead of staying here It was News when the paper appeared on falklumo.com/lumolabs. Of course, it's no News anymore (except if there are new developments to report about like the effect of the recent firmware update). Maybe, others have an opinion if now another section would be better suited? I am undecided because theoretically, any thread in this section would have to be moved off section when it is no longer new or rumor; but actually never is.

08-26-2010, 04:55 PM	#125
bjan Senior Member Join Date: Feb 2010 Posts: 116	Thanks Falk for your extensive and polite replies. I will do some more testing including your recommendations. However I do not see anyhow why I repeatedly do not get any "pinsharp" shots with 17mm at 1/100 and a always "pinsharp" shot at 1/850 with a camera that has SR used by an experienced steady arm and hand . We will sees what my future tests will bring and I will keep you posted. By the way I do still LOVE my K7 . But... a little dent in our loveaffair. A bit more open for flirting .

08-27-2010, 01:18 AM	#129
dlacouture Veteran Member Join Date: Jul 2008 Location: Var, South of France Photos: Albums Posts: 1,074	Originally posted by bjan Thanks Falk for your extensive and polite replies. I will do some more testing including your recommendations. However I do not see anyhow why I repeatedly do not get any "pinsharp" shots with 17mm at 1/100 and a always "pinsharp" shot at 1/850 with a camera that has SR used by an experienced steady arm and hand . We will sees what my future tests will bring and I will keep you posted. By the way I do still LOVE my K7 . But... a little dent in our loveaffair. A bit more open for flirting . And try also at 1/10 or 1/20, you should get sharp pics again...

08-27-2010, 02:42 AM	#130
bjan Senior Member Join Date: Feb 2010 Posts: 116	Yeah.. and with 1 minute exposure on a tripod with no moving subjects around things should be quit sharp as well ! I JUST DON`T WANT A CAMERA THAT I HAVE TO WORK MY AROUND A 1/80 OR 1/100 SHUTTERTIME WITH

08-27-2010, 02:54 AM	#131
axl Veteran Member Join Date: Mar 2007 Location: Nove Zamky, Slovakia Photos: Gallery \| Albums Posts: 7,183	I apologize but I didn't go though all of the pages, but does K-x have the same/similar issue?

08-27-2010, 04:15 AM	#132
alessandro63 Forum Member Join Date: Jul 2009 Location: Italy Posts: 57	Originally posted by falconeye Some testers even tape the focus ring to make sure the focus stays fixed (not required with Pentax as it has no "fly-by-wire" focus). In Pentax cameras, as in any other DSLR, you can just decouple the focusing from the shutter button, really no need to tape anything nor to switch to manual focusing. And of course, if pressing manually, much better to use delayed shutter. What's impressive is the quantity of variables one must keep in account to try to verify if this issue exists: what do you think is the real incidence of this problem in real life shots? I mean: not detracting anything from your research, it appears that the chance to have a blurred shot caused by the shutter is a very very secondary one, cause it's impossible to eliminate the sum of all the other causes, that appear to be of greater amplitude. Cheers Alessandro

08-27-2010, 04:50 AM	#133
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871 Original Poster	Originally posted by alessandro63 In Pentax cameras, as in any other DSLR, you can just decouple the focusing from the shutter button, really no need to tape anything nor to switch to manual focusing. Yes, or one uses the AF button to disable focus when pressing the shutter What I meant was some camera makes where mounting a lens to a body may change its focus (during protocol initialization) even if all settings are manual. And testers sometimes have to switch lenses within a series and so some tape the lens. Originally posted by alessandro63 What's impressive is the quantity of variables one must keep in account to try to verify if this issue exists: what do you think is the real incidence of this problem in real life shots? Alessandro, your point is valid to a point. We wrote in the Understanding Image Sharpness Paper about. All the factors which add to blur ... But the problem is relevant in real life nevertheless. I wouldn't say it is the #1 cause for blurred images which is why I can live with that. But make a thought experiment: Assume you have 4 causes each having a 50% chance to blur an image (like defocus, lens softness, motion blur, shutter blur -- simplified model for our thought experiment!). Then the chance for an unblurred image is 6% only. Which isn't that unrealistic by the way. Tack-sharp images are the exception, not the rule (at least in demanding rather than tourist-snapshot situations). If you can then eliminate one reason for blur, the chance for an unblurred image raises to 12%. Twice as many tack-sharp images. So, even though the single cause is largely dominated by the other causes for blur, it still makes a difference. Reasoning like this can be counterintuitive sometimes.

09-15-2010, 02:42 PM	#134
ihasa Veteran Member Join Date: Jul 2009 Location: West Midlands Photos: Gallery Posts: 2,066	Debating with myself whether to send my K-7 back. I have managed to replicated the shutter blur effect and while yeah, it's work-around-able, avoiding 1/80-1/100 with wide angle lenses is not ideal. That shutter speed corresponds to f8-f11 apertures in typical cloudy weather at 100ISO. This is the kind of thing I could forgive a cheap body like the K-x, but not a super-expensive camera like the K-7. Another thing which occurs to me is that the K-x is more flexible at getting round this problem (if it also suffers from it) because you don't have to worry so much about bumping up the ISO. On the other hand, I'm liking most other aspects of the K-7. I hope Pentax had this issue in their minds when they designed the K-5!

09-15-2010, 04:55 PM	#135
cfraz Veteran Member Join Date: Jan 2009 Location: Oregon, USA Posts: 521	Quote: Maybe, others have an opinion if now another section would be better suited? I am undecided because theoretically, any thread in this section would have to be moved off section when it is no longer new or rumor; but actually never is. The news was that you did some experiments and wrote up the results. The content has significance beyond the news item that may be important in discussions of future (and past!) generations of DSLR's, so I think the discussion rightly belongs in DSLR section. Maybe having the main discussion in DSLR with a post in News with a pointer to the main discussion thread is best. Anyway, that would be my vote should you do some work on, say the K5 or K-r (hint hint).