Shake reduction off for tripod use - why?

If someone could explain the theory of this I would be grateful. After all if I have very steady hands and shooting at a high shutter speed how does the camera know it's not on a tripod and SR would be on as default. A supplementary but related camera shake question - I don't think my K-m has a mirror up mode to reduce by vibration but I gather this occurs in timer mode (remote timer as well?)
Dave

You may have steady hands, but a tripod generally is steadier

The shake reduction (SR) is designed to compensate for your hands movement (I think muscles have a natural tremor around 10 Hz). At high shutter speed SR does not help (I have the feeling that it may be even affecting the image negatively at very high speeds 1/750 s or so; no trials made on this one so far, though).
My guess (and I would need to read up on this) is, that when the camera is on the tripod the SR's acceleration sensors don't give a signal but, being an electronic circuit, as noise is always present this leads to tiny accelerations being detected and therefore the sensor moved to compensate for these ghost motions.

When using the timer modes (2s or 10s, I believe) then the camera assumes that it is on a tripod (or put on a surface that doesn't move) and therefore disables SR. This is the only way for the camera to know (or better assume) that it is on a tripod.

BTW: For the K20 it is the same, mirror up is activated in the timer modes but no way to do it manually (or at least I never have used (or missed) such a setting).

Prieni

In addition, with the K20D and later models the sensor is clamped into position when SR is off.

For the ultimate sharpness that has to be better than it being held in position by magnetic fields.

It is? I wonder how.

Dan

Well I must admit that SR is always switched on, but I rarely take anything beyond 1s even on a tripod.

The only time I switched it off, I forgot to switch it back on again

When you use an infrared remote it also turn off the SR, don't know if it does it when connected to the PC or with a wired remote.

I'm am always forgetting to turn off SR and then turn it back on again...

Well you'd be a lot better off leaving it on then.

Lots of people have speculated along Prieni's lines...
... and it is superficially plausible.

However, no one, to my knowledge, has come up with a shred of actual evidence supporting such claims, in the nearly three years I've been following the discussions on the topic. If someone cares to lend me a cable release that's K10D compatible (or better still, give me one for Christmas ), I'll repeat the experiment I reported some time ago.

In the meantime, I continue to leave the SR switch in the 'on' position, tripod or not.

mine is always on. i do wonder though, when not it is on and not required, in some way can this affect the overall results of the image?

That's what I do as well. But on the tripod it actually is off, as I always use the 2s delay on the tripod.

And yes, I'm often surprised when I want to take a shot and all goes dark in the viewfinder because I forgot to disable the 2s delay again...

Prieni

Gets me as well
Matt

Yes, me too. Or the 3s delay with the IR remote.

The one thing I would like to try, as I say, is a cable release. There is a hint of ambiguity in the K10D manual, where it says:

[quote="K10D manual"]... SR automatically turns of in the following circumstances:

Self-timer, 2s self-timer, remote control shooting, 3s delay shooting, bulb shooting, or wireless mode with external flash[/quote]At a stretch of the imagination, you could just about interpret this as implying that with a cable release (as distinct from an IR remote), it doesn't switch off.

Please could someone with one, plug it in and see whether SR switches off automatically or not?

Yes, me too again, many times. I've lost quite a few grab shots that way...

Chris, will give it a try tonight.
I've both the IR and a cable release.

Can't comment on whether or not is it, but if it is, it is probably done with a small solenoid.
Some of the CCTV cameras we use have a green filter over the sensor in daylight and when they switch to mono for low light images a tiny solenoid moves the filter out of the away. Probably the same sort of thing to clamp the sensor.

I can only tell you what I've read. How the sensor is clamped I have no idea, but it seems a better idea thatn having it magnetically floating at all times.