View Full Version : Pentax Shake Reduction

10-05-2010, 9:31am
Some interesting information...


(Small screen shot, copy considered fair use for education, reporting etc)

10-05-2010, 6:05pm
G'day Kym

okay ... my exposure system's not fully tuned - what are you trying to tell us?

Regards, Phil

28-05-2010, 10:54pm
some light reading (not) on the subject


this guy has a lot of interesting pentax info

28-05-2010, 11:15pm
I just wish they would change the name. I'm sure it sounds great in Japanese, but in English, "shake reduction" always sounds like something you buy from Jenny Craig, a low-fat milk substitute, presumably. They sjould have called it something short and easy to remember, such as ISVROISSRSS.

29-05-2010, 9:57am
About 2 or 3 Schooners works for me !!!!

29-05-2010, 2:27pm
lets not even consider VR then! ok canon wins with IS but I think pansonic with Mega-OIS is good too


I have just been reading your old post on cropping and effective image size wrt bird photography, very imformative thanks.


29-05-2010, 2:28pm
yes it was rather heavy going

29-05-2010, 2:49pm
LOL! @ Tannin(as per usual! :D)

kind'a more seriously I find point 2. hard to believe!

mirror slap resonance is not only closely related to the particular lens used(and subsequently focal length), but 100% dependent on it.
I can't believe that with a 500mm(or longer lens) with a very long lens barrel, overhanging(by a country mile) forward of the COG wil never cause movement to the point where even the best optical stabilisation application will not succeed!

The problem I have with 'Shorty'(500mirror) is that the issue is based on the Chaos Theory. I can get sharp shots at 1/60 one moment and a total loss the next at 1/500th, due to mirror slap. And that lens is short!
Add any TC to a 500mm lens and I think point number 2 will fall down into a heap very quickly!

this test only encompasses a 50mm lens.

I find it hard to believe too that mirror slap on a 50mm lens(on a good tripod/head of course!) will be evident at 1/125-1/80s!!

So(out of curiosity) is the sensor able to move freely with SR turned off? I would havethought that the SR mechanisms themselves would be a rigid structure.

That is; whatever the arms or legs that hold the SR mechanism to the sensor would be rigid, or that the SR would be locked down tight and rigid itself.
If any of the links from body to SR mechanism to sensor are not properly rigid(or rigidly controlled) then SR would be a random event. :confused013

OH! and by the way you forgot the most important piece of information!!..

Quote from the same author:

The prior expectations of the photographer may also have a large bearing on the outcome. It
is hypothesised that Shake Reduction technology leads photographers to relax their
standards of care and this in turn is a cause of unsharp images. A study to test this hypothesis
should also be carried out.


you slackass lazy Pentaxians!!

29-05-2010, 3:27pm
OK, Arthur. It's lousy weather here and I'm not going out, so I might as well waste the afternoon addressing your post as spend it any other way. :)

I can't believe that anyone would manufacture, let alone use, a 500mm lens that didn't have a proper tripod mounting ring, and thus is not set on the tripod roughly in balance. (Not counting your weirdo mirror thing, which would fit in a pocket if you aren't too fashionable.)

I'm only guessing, but to read between the lines of the quoted text, I don't think they are talking about mirror slap resonance of the whole camera-lens system. It reads more like a dismissal of a phoney claim to the effect that the sensor shake electro-mechanical compensation system can get into a resonance loop with the physical camera/lens system. Feedback/resonance loops like that are common in many fields of engineering, and you would expect any designer worth his salt to be aware of the possibility, and expect to see the design team spend time working to eliminate exactly that problem very early in the development cycle of the product.

3: "The prior expectations of the photographer may also have a large bearing on the outcome. It is hypothesised that Shake Reduction technology leads photographers to relax their standards of care and this in turn is a cause of unsharp images."

OK. I'll buy that. But it can work in reverse too. As you know, I have to do most of my landscape work handheld because of the physical difficulty of carrying two tripods around. This makes life difficult when the light isn't strong, but I have come to have a lot of faith in the wonderful image stabilisation of my two workhorse landscape lenses, the 24-105/4 and the 100-400/4.5-5.6. Using those lenses, I feel relaxed and confident that, with a little care, I can get good, sharp shots at insanely low shutter speeds. So I hold them right and don't tense up and the shots are good. Then I pick up a different lens without IS and I try too hard and smear shots I should nail without difficulty.