Optical Stabilisation Vs Shake Reduction.

I find SR shots sharper at lower speeds, but always take three or four if possible to make sure I can choose the sharpest.

Perhaps you are shooting before it stabilises CyclopicFun? The EXIF data will tell you.

Curious, I do exactly the opposite. The OS of the Sigma lenses has 2 options, 1 = horizontal and vertical stabilisation, and 2 = only vertical stabilisation (for panning left to right or vice versa in landscape orientation). When panning, you don't really want horizontal stabilisation because as you pan (move) the camera left or right, the horizontal stabiliser could ruin the image.

That's as I understand it anyway.

The Pentax in body SR system is either on or off in all axis' with no possibility to limit it to only one plane. I think it caters for rotational movement as well as horizontal and vertical.

I'm not sure if Sigmas system can deal with rotational movement, but I think not.

I just don't seem to get on with Sigma OS option 2 ... come to that I don't use option 2 (panning mode) on my Canon L lenses either.

I use mode 2 on the Sigma 70-200mm at the track when taking panning car shots. Works well.

To reawaken this old thread, just as far as in-body shake reduction is concerned.

Common sense suggests that SR will be most effective with slow shutter speeds. I don't know how fast the mechanical response time is, with recent Pentax models, but surely when one is exposing for, say, 1/1000 sec or faster, SR cannot significantly improve sharpness.

Of course, the focal length will come into the calculation, but is there any data to suggest the shutter speed above which SR contributes little if anything to an average photo taken with a 35mm lens on an APS-C camera?

I've only seen tests from the K-7 and K-5 which showed SR most effective a few stops either side of 1/20th sec. and hardly any advantage at around 1/125th or faster.

The SR has improved since but I wouldn't expect much improvement at fast speeds.

See....
http://blog.falklumo.com/search/label/shake%20reduction

Fuji owners have this to help them

https://fujifilm-blog.com/2016/06/16/banish-camera-shake-with-a-stringpod/
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Personally I use the old shutter speed vs focal length calculation, anything below I use SR and anything above I switch it off. I do find that at high shutter speeds having SR on gives me less keepers when doing an air show.

Having tried in lens OS on a canon for the first time recently, I was blown away. Stabilising whilst lookong through the viewfinder was excellent, and something I really wish I had.

It's been available for years on Pentax via certain Sigma lenses. The 150-500mm is quite impressive and also useful for use on a tripod when 500 or 500+TC will still shake.

I never though about it before, but it probably makes manual focus easier if the image is stationary.

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