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08-26-2010, 05:41 AM   #106
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bjan, relax!
The first one is out of focus. Look at the hedge.

08-26-2010, 05:47 AM   #107
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QuoteOriginally posted by bjan Quote
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.
The problem here is no one is sure if this can be resolved with a firmware fix, or if it would require a hardware modification. Reports from users at DPR suggest that Pentax has refused this as a warranty issue, meaning that the performance is within their accepted guidelines, at least as Pentax stands now. This is also an issue with the K-x.

Your option as a consumer might be to:

1) Send it in for warranty with demonstrable evidence.
2) Ask for a refund and move to another brand.
3) Buy a newer model without this effect.
4) Small claims court for lesser performance than specified.

Somewhere in California someone may be prepping a class action lawsuit

Will Pentax be compelled by market, legal, or regulatory forces to indemnify K-7/K-x consumers? Hard to say. Many people just move on.
08-26-2010, 05:53 AM   #108
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QuoteOriginally posted by blende8 Quote
bjan, relax!
The first one is out of focus. Look at the hedge.
Not necessarily, to get the 1/800s speed he probably had to use a wider aperture. Anyway the test is not very good if two different apertures were used, if the camera was refocused between shots, etc. Maybe shutter blur, maybe not. Anyway this is a serious issue and may explain why I got less than satisfactory results using polarizers (using them will often lower my shutter speed to around the 1/100s).

Last edited by ManuH; 08-26-2010 at 06:22 AM.
08-26-2010, 06:02 AM   #109
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Which apertures where used? (Perhaps refraction is involved in this particular example.)

08-26-2010, 06:04 AM   #110
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QuoteOriginally posted by ManuH Quote
Not necessarily, to get the 1/800s speed he probably had use a wider aperture.
Ah, of course, you are right!
08-26-2010, 06:22 AM   #111
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F3.2 for the 1/800 THAT EXPLAINS THE HEDGE mr "BLENDE 8 " F8 for the 1/100 shot.
I do really know how to focus correct and the result is quit shocking so if anyone has good story to it it would be fine. The test is still very good with these 2 apertures because both should give a more or less equal sharpnes on a vertical area as in this sample. especially with this lens that is not a no go in this respect of sharpness with these apertures especially as these crops are from the middlle of the orignial picture. So no excuses found yet as far as I am concerned . (I would like to find one though in order to be wrong with my findings)
08-26-2010, 08:00 AM   #112
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QuoteOriginally posted by bjan Quote
So no excuses found yet as far as I am concerned . (I would like to find one though in order to be wrong with my findings)
It could be that your lens does make a pronounced focus shift when changing aperture values. Just a wild guess. You could find out by trying a series of manual focus shots where you change manual focus gradually between shots.

To be sure that you are seeing shutter-induced blur, try to make another exposure at ~1/20 (with SR on). It should be sharper than the 1/100 shot.

You could also closely examine the blur of your 1/100 shot to check for vertical motion blur. If you are seeing horizontal motion blur or just defocus blur, you are not seeing the shutter-induced blur Falk et al. wrote about.
08-26-2010, 08:33 AM   #113
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QuoteOriginally posted by bjan Quote
F3.2 for the 1/800 THAT EXPLAINS THE HEDGE mr "BLENDE 8 " F8 for the 1/100 shot.
bjan, you may have given a valid example or not.

In our study, we found it rather difficult to first eliminate/equalize all other sources of blur and set a stage for accurate measurements.

One way to work around some of the problems is to use smaller increments in shutter speed (use 1/320, 1/160, 1/80, 1/40), use ISO 100-800 with constant aperture and fix focus (LV focussing). If the depth of field isn't at least 1m, use a bean bag tripod as one moves easily forth and back using the camera handheld. Use SR at 1/40s handheld at least. The subject is good enough to see the effect. Maybe, make one more image at 1/80s in portrait orientation to see if the horizontal structure gets sharper.

08-26-2010, 09:51 AM   #114
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thanks for comment Falk.
I did use a bean bag. I did do increments and found slighter differences. this was the most extended difference and I could repeat the result over and over. The distance I took the Phot from was about 75 centimetres so we talk about roughly 30 till about 75 centimetres DOF available for the pictures taken ( 3.2 and 8 AF), this is more than enough to avoid any problems with DOF in this vertical example . (lens length was 17mm)
Going down from 1/100 things improved a little but did never reach the 1/800 sharpness.
With or without SR (on the lower times) Would you consider the results of my test valid as a result of shutter blur and cooping with the outcome of your research ?
08-26-2010, 10:01 AM   #115
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What other factor than shutter blur could anyone think of (giving no camerashake (shot on beanbag on a steady table) and no misfocussing ) ?

Condider that my examples photo`s could be repeatedly taken with same results
08-26-2010, 10:37 AM   #116
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QuoteOriginally posted by Aristophanes Quote
The problem here is no one is sure if this can be resolved with a firmware fix, or if it would require a hardware modification. Reports from users at DPR suggest that Pentax has refused this as a warranty issue, meaning that the performance is within their accepted guidelines, at least as Pentax stands now. This is also an issue with the K-x.

Your option as a consumer might be to:

1) Send it in for warranty with demonstrable evidence.
2) Ask for a refund and move to another brand.
3) Buy a newer model without this effect.
4) Small claims court for lesser performance than specified.

Somewhere in California someone may be prepping a class action lawsuit

Will Pentax be compelled by market, legal, or regulatory forces to indemnify K-7/K-x consumers? Hard to say. Many people just move on.
And ask Toyota for some advice...
08-26-2010, 11:55 AM   #117
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Interesting you're bringing up Toyota. Due to a huge media campaign, everybody "knows" how much of a deathtrap their cars are.
Of course, it's all fiction - Toyota isn't any worse than other manufacturers, some of which had much to gain from all these scandals. Even fake "science" was deliberately used in order to "prove" the unprovable - it didn't work.
And now, we're close to find, well... that they aren't any worse, their cars are as safe as other's.

Would we find the same about Pentax? That they aren't worse, their cameras are not junk - but actually quite capable tools?
Fortunately, we don't have a "professor Gilbert"; but it's not the first time I'm hearing about a class action. Is our cameras that bad?

Well, as a Pentax/Toyota owner, I know the answers But do you?
08-26-2010, 12:30 PM   #118
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QuoteOriginally posted by bjan Quote
What other factor than shutter blur could anyone think of (giving no camerashake (shot on beanbag on a steady table) and no misfocussing ) ?
Difficult to say. Shutter blur s the most likely cause. But you cannot be sure. F8 should avoid focus problems IF you didn't change the focus distance. On AF, the variation in focus may be more significant than anything else. Even at F8. Ultrawide angle lenses cause some trouble with AF. You really would like to check in 90 portrait or at 1/40s to have another point of reference as well.

With my 12mm Sigma lens, I've seen the AF focus to anything in between 0.7m and 1.2m with a target 2m away. I would say that the 1m offset is due to imprecise labelling of the lens' distance scale. But the 70% variation is worrysome. So, manual and constant focus is mandatory for this kind of pixel-peeping tests.

I am a bit worried that the blur in your case doesn't look asymmetric and that you seem to see a difference between 1/250s and 1/800s which we didn't see in our study. Did you use a remote trigger (or timer)?


P.S.
There are lenses which are sharper at f/3.2 than at f/8. In the center at 17mm, even the 17-70mm is sharper at f/4 than at f/8. Don't know which lens you used though and the effect is marginal anyway.

Last edited by falconeye; 08-26-2010 at 02:21 PM.
08-26-2010, 01:24 PM   #119
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QuoteOriginally posted by bjan Quote
What other factor than shutter blur could anyone think of (giving no camerashake (shot on beanbag on a steady table) and no misfocussing ) ?
Did you see my post at all? I offered an explanation (AF problems) and ways to check what kind of problems you are facing.

Admittedly, an aperture-induced focus shift is unlikely to produce such an outcome but doing a manual focus bracketing as I suggested would help to eliminate AF problems from the puzzle. Also, examining the nature of the blur (directionless -> misfocus, vertical -> shutter-induced, horizontal or mixed -> camera shake caused perhaps through shutter release) is key. If you don't have a remote control, use the 12sec timer option to eliminate shake from pressing the shutter release button.

Last edited by Class A; 08-26-2010 at 01:35 PM.
08-26-2010, 03:05 PM   #120
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QuoteOriginally posted by Kunzite Quote
Interesting you're bringing up Toyota. Due to a huge media campaign, everybody "knows" how much of a deathtrap their cars are.
Of course, it's all fiction - Toyota isn't any worse than other manufacturers, some of which had much to gain from all these scandals. Even fake "science" was deliberately used in order to "prove" the unprovable - it didn't work.
And now, we're close to find, well... that they aren't any worse, their cars are as safe as other's.

Would we find the same about Pentax? That they aren't worse, their cameras are not junk - but actually quite capable tools?
Fortunately, we don't have a "professor Gilbert"; but it's not the first time I'm hearing about a class action. Is our cameras that bad?

Well, as a Pentax/Toyota owner, I know the answers But do you?
When I was a youngster, and once 18 years old, my first car was a Corolla, the 2nd, 3rd, 4th and… 8th were all Corolla's. I had them all in about 3 years, second-hand and very old and 'tired'. The secret : my uncle was a Toyota dealer!
Now I drive Volvo, I presume for the rest of my life…
I do shoot Pentax (LX) too, since 1985, hopfully for…
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