[Robert N]

Regarding shake reduction (SR) performance in the K-3, is anyone aware of a Pentax SR performance curve that relates to lens focal length.
I am making the assumption that the limitation of movement of the camera sensor during shake reduction will tie in to a maximum lens focal length, after which the shake reduction benefits will be minimal. From my own experience, SR performance up to around 200mm focal length is excellent. With a 300mm lens, from trials, the 'norms' I stick with are minimum shutter speeds (static subject) for optimum sharpness of 320th sec. (hand held), 250th sec. (monopod), 160th sec. (tripod). For longer lenses (typically the HD PENTAX-D FA 150-450mm F4.5-5.6 ED DC AW at the 450mm end), how do users find this lens performs with and without SR for static subjects.
Looking forward to members comments.

[savoche]

I usually operate with "sharp enough" rather than demanding "optimum sharpness" in all situations. At 300mm I try not to go below 1/180th hand held. Slower than that the "sharp enough" rate drops quite a bit. On tripod I switch off SR to avoid having it induce camera shake.

[photoptimist]

My experience with the K-5 and K-1 suggests that SR performance is linear with focal length and is typically a couple of stops. Thus, I'll use a 300 mm lens with shutter speeds as slow as 1/90 or 1/60. Coffee, hunger, and wind degrade SR performance. A calm mind, calm wind, and solid footing can help. For extra assurance, I sometimes squeeze off a couple of shots with deep breathes in between each one to maximize the chance of a sharp "keeper."

Note: SR on a monopod or tripod can be tricky and is generally not recommended. Depending on the exact structural properties of the support, head, and the mass of the lens, the use of SR on a pod might work well or might be an absolute disaster. Under some conditions, the control loop for the SR system can make the camera-tripod system vibrate violently. If you put the camera on a tripod, enable liveview, zoom in on the screen, you can sometimes see the effect. Instead of stabilizing the live view image, the SR system will make in vibrate. In the worst situations, the thing sounds like a very angry wasp.

[othar]

While you are likely correct, that the maximum benefit of SR will decrease with increasing focal lenght, because the sensor has to move further to eliminate the same amount of camerashake, this issue is typicaly taken into account with the rule of thumb to use faster shutter speeds than the reciprocal value of your focal lenght (or 2x your focal lenght, maybe 1.5x too depending on sensor size; there are some variations of this rule)
That beeing said I have been able to get useable (not overly sharp but reasonably sharp) pictures at 1/25 sec with a 400mm lens on APS-C in very bad lightning (but a very good day steady hand wise )

[pschlute]

I always prefer to try and get optimal shutter speed with a long lens rather than rely on SR to make up the difference. But it works exceptionally well

[garywakeling]

My experience with the K-5 and K-1 suggests that SR performance is linear with focal length and is typically a couple of stops. Thus, I'll use a 300 mm lens with shutter speeds as slow as 1/90 or 1/60. Coffee, hunger, and wind degrade SR performance. A calm mind, calm wind, and solid footing can help. For extra assurance, I sometimes squeeze off a couple of shots with deep breathes in between each one to maximize the chance of a sharp "keeper."

Note: SR on a monopod or tripod can be tricky and is generally not recommended. Depending on the exact structural properties of the support, head, and the mass of the lens, the use of SR on a pod might work well or might be an absolute disaster. Under some conditions, the control loop for the SR system can make the camera-tripod system vibrate violently. If you put the camera on a tripod, enable liveview, zoom in on the screen, you can sometimes see the effect. Instead of stabilizing the live view image, the SR system will make in vibrate. In the worst situations, the thing sounds like a very angry wasp.

I love the angry wasp description, I have heard the wasp and never understood why until now

[tduell]

I pondered on this question shortly after I started using the DFA 150-450, and asked a question here.
If I recall correctly it was suggested that the 4-4.5 stops available from the K-3/K-3II was with a focal length of 85mm. Not sure where that came from.
If that's correct, I would assume that longer focal lengths could expect less.

Cheers,
Terry

[Robert N]

Many thanks to all for your replies on my K-3 SR performance curves query.
No one has identified a definitive limit to focal length the SR system can handle, which is encouraging news. Certainly up to medium telephoto lengths, the SR works superbly - for my 16-85mm lens, I can hand hold at one 10th second and still get pin sharp images. I still stick with my 'norms' with SR on, when using a 300mm lens, even with monopod and tripod use as the monopod always generates some movement and even when pressing the shutter button on a medium weight tripod, again a slight camera movement occurs.
When using the remote 'mirror up' mode on a tripod, of course the camera automatically switches off the SR.