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02-27-2010, 07:21 AM   #46
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QuoteOriginally posted by Wheatfield Quote
I believe earlier in the thread I indicated that with careful shooting technique, Pentax shake reduction would probably net well over a 4 stop advantage.
However, I also believe that the results that we were directed to in post #29 are probably false, and I took the time to explain why, and expanded on that somewhat with an explanation of scientific testing.
It's a a pity that you are so argumentative that you can't see when you are being agreed with.
It's more the comment that went "People who start changing all sorts of parameters during a "test" and then drawing a conclusion are idiots." that offended me. Especially since I just spent 2 hours doing my own tests and then drew some conclusions from it. My poor, delicate sensibilities got bruised when I got called an idiot out of the blue like that.

QuoteOriginally posted by Wheatfield Quote
Well, you do have a good handle on arrogance yourself. I suppose that for you, looking at me is like looking in a mirror.
nooooo! I don't want to be a bad Canadian! NNNOOOOO!!!!

In any case, this whole debate is pointless. You said it yourself, someone with an excellent shooting technique could probably yield better results than a 4 EV improvement. Trying to gauge the effectiveness of SR in a scientific way would prove nothing, since every photographer has a different technique and different physical capabilities that affect how much camera shake gets induced under different circumstances. For me, I got a between 3 and 4 EV improvement. Someone with a really poor technique or super weak arms might get better results from a 10-year old in-lens IS system.

(oh no! I just made my own poorly-veiled insult towards some poor, innocent person!)

However based on my own tests, I CAN draw the following conclusions:

- *I* gain a 3-4 EV improvement with firmware 1.03 and shake reduction enabled

- *I* can get sharp pictures down to 1/6 shutter speed at 135mm from 30 feet away with shake reduction enabled

- *I* only gained a 2 EV improvement with firmware 1.01 and shake reduction enabled (I downgraded the firmware to confirm this)

- The results of my experiment were repeatable. I just finished doing the same experiment with each firmware version 2 more times each, and I got about the same results +/- 5%.

02-27-2010, 07:46 AM   #47
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QuoteOriginally posted by GoremanX Quote
However based on my own tests, I CAN draw the following conclusions:

- *I* gain a 3-4 EV improvement with firmware 1.03 and shake reduction enabled
Looking at the results you posted in post #20 I would say 3EV improvement, (which is much better then I do with my K10d), but you cant really claim 4EV based on those numbers as I understand it.
02-27-2010, 08:05 AM   #48
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QuoteOriginally posted by Gimbal Quote
Looking at the results you posted in post #20 I would say 3EV improvement, (which is much better then I do with my K10d), but you cant really claim 4EV based on those numbers as I understand it.
I suppose my results at 1/100 were pretty close with and without SR, so it's hard to claim an "improvement" there. I should've tried going slower than 1/6 to see if I can still get sharp shots with SR turned on...
02-27-2010, 10:12 AM   #49
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QuoteOriginally posted by GoremanX Quote

nooooo! I don't want to be a bad Canadian! NNNOOOOO!!!!
It's probably because we have been importing our culture for so long now.

02-27-2010, 01:15 PM   #50
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QuoteOriginally posted by Gimbal Quote
Looking at the results you posted in post #20 I would say 3EV improvement, (which is much better then I do with my K10d), but you cant really claim 4EV based on those numbers as I understand it.
Yes, with our "old" K10 and K20 bodies 2 f-stops is a good upper limit and about 1.5 f-stops is more the realistic average. I never got those 3 f-stops by SR.

BUT what really helps is a good shoulder mount. With my Novoflex 400 I can usually handhold 1/100s and sometimes even 1/40 is tack sharp.

Ben
02-27-2010, 01:28 PM   #51
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QuoteOriginally posted by Ben_Edict Quote
BUT what really helps is a good shoulder mount. With my Novoflex 400 I can usually handhold 1/100s and sometimes even 1/40 is tack sharp.
well... yeah, but a shoulder mount is like a different type of shake reduction.

I wonder how slow I could get the shutter speed to go with my K-7's SR enabled and a shoulder mount? I bet I could get sharp pictures at 0.5!!! (as long as the subject is immobile)
04-13-2010, 03:05 PM   #52
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My reinterpretation of the work of P.Smith

I have worked out a reinterpretation of the wonderful work of P. Smith.

First, go have a look again at his admirable work as linked by the OP:

-> Study of the Effectiveness of Shake Reduction in the Pentax K7

BTW, anybody knows who P. Smith is?


Basically, what I did is extract the data and error margins and replotted them as blur-widths (in px) plus upper/lower std.deviation margins against the exposure time (in ms).



Then and within error margins (exceptions noted below), I do basically find a linear relationsship between blur width and shutter speed. Just as one may naively expect.
My results in a nutshell:
  • Result applies to a focal length of 50mm. Other focal lengths not studied!!
  • Result applies to the Pentax K-7 camera owned by P.Smith. Sample variation not studied.
  • Result applies to handholding shake of P.Smith. Other shakers not studied.
    -- end of disclaimers --
  • Shake reduction on/off has no significant effect at 1/100s and below.
  • Shake reduction is fully effective at 1/50s and above.
  • Shake reduction delivers an advantage of 3.0 stops between 1/50s and 1/8s (as derived by comparing the slopes of the two dotted lines in the graphics).
  • Shake reduction is most effective around 1/25s where it delivers an advantage in excess of 4.0 stops.
  • Shake reduction is less effective at 1/6s (and probably above).
  • With SR, acceptable blur widths (0-2px) are possible with 5x the exposure time (150 ms vs. 30 ms or 2.3 stops).
  • As a rule of thumb, shooting at x times 1/focal-s shutter speed yields 4x Ám shake without and 0.5x Ám with shake reduction (e.g., x=2 for 1/25s at 50mm).

In summary, SR delivers between 2.5 and 4 stops advantage in the range of shutter speeds requiring stabilization for 50 mm.


Because shake with SR on is so exceptionally low around 45 ms (1/22s), it may be a good advice actually to set exposure time accordingly. At this exposure time and 1/20s - 1/25s, the K-7 SR in P. Smith's hand and with 50mm delivers tripod-quality sharpness!

Last edited by falconeye; 04-13-2010 at 03:15 PM.
04-13-2010, 03:32 PM   #53
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I'll say that I miss SR dearly with my D700 (not having any VR lenses yet), despite its ISO advantage.

04-13-2010, 11:25 PM   #54
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Avast! Only ye weak landlubbers need this Shake Reduction mumbo jumbo! Aye, true sailors balance on the one wooden leg...









Haha! I only kid.. :-p
04-14-2010, 07:20 AM   #55
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QuoteOriginally posted by falconeye Quote
BTW, anybody knows who P. Smith is?
P. Smith is our new member labnut
04-14-2010, 11:41 AM   #56
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Read all about it in this thread:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/97590-pentax-shake...ited-test.html
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