Why Does SR lower The Shutter Speed?

I meant to post this the other day but it slipped my mind with everything else that was going on with my K20D.

I was attempting to shoot a duck sitting on a rock in the middle of the river, couldnt get a position i like with my Tripod so opted to hand hold.

With the Tripod i was getting f8 and a shutter speed of 400 @ iso 800.

When i removed it from the Tripod and turned SR on it dropped to a shutter speed of under 200.

Anyone any ideas why it does that?
Ive used Canon IS and Nikon VR lenses and never recalled them doing that when the IS or VR was switched on.

To properly answer this we would need to know more about your other settings such as metering mode and if the light changed when you moved your camera.

Many factors contribute to shutter speed, SR is not one of these that I am aware of. However, since SR is on the camera may choose a lower ISO for more quality, knowing that you have more latitude.

I am not aware of this behaviour happening on my K10D.

What program mode were you shooting at Craig? That is quite interesting, never noticed it, but again I never looked for that.

The lighting probably changed. I've never noticed any
difference.

shim

My thoughts precisely. I have often used P Mode to fire quite a few shots successively within seconds of each other and noticed that there are changes in the EXIF in the shots

Although the shutter is stepless, the readout is not, so it only shows an approximation. If the light level is very close to another value then moving the camera slightly may trip it into another value.

The simple answer is that you moved the camera and the light reading changed. Nothing to do with SR.

Craig, must be due to light changes, doesn't seem to have been affected by the SR.
I just did a simple test by flipping the SR switch on and off while taking the shots handheld and no changes there.

Definitely seems that when you moved from the tripod to handheld there must have been light changes, or any other changes that must have affected your SS

Thanks for the replies guys, those were my initial thought also but it happened everytime i removed the camera from the tripod and turned on SR.

Setting were in AV for that scenario, but i noticed that in other modes it would give me ISO warnings.
ISO was set manually, set to f8 in AV mode.
Tripod Mounted around 1/400, SR on around 1/200 or lower.
I wont be getting my K20D replaced for a few days it seems so i wont be able to do a Tripod SR off, Tripod SR On test to see what happens.

I think the answer is probably quite a simple one:

With the camera on the tripod were you looking through the viewfinder when you took your shot? Moving your eye away from the VF (and not covering it) allows more light to fall on the metering sensor and so will change the exposure value given by the camera.

Is it not possible that the camera was actually in program mode, and when SR was turned on, it knew that a lower shutter speed would work - thereby enabling it to use a smaller aperture for greater DOF and/or better sharpness.

There was no way for it to know when it was on a tripod, and it would then have used a "safe" speed.

G

George, I wrote the same comment but try it for yourself there is no difference

Flicking the switch on and off, while the camera is on the tripod would seem to be the conclusive test.

Where?

G

Not in this topic Stefan.

I did but deleted it soon after, since I tried it out right away and didn't found out to be true.
I wrote it before or after CraigF1969 second messages so he or Hefty should have gotten an email when I posted the comment.
Maybe they, a moderator or someone else behind the forum can confirm that but you need to take my word on it now