What's causing this?

Not in my experience it doesn't. My camera is quite often set to wireless flash, and SR works normally.

Nooooooo.... not again!!!!!!

Has there been any new evidence I've missed since the last time I had a rant on this subject? If not, I'm still convinced this is an urban myth.


Do any of the instructions books also say why they say this? The Pentax ones don't, AFAIK.

P139, K-5 manual

No they don't say why Chris, but they all say it. Given that the manufacturers are in accord, perhaps we should believe them? After all, there doesn't seem to be much evidence that it isn't true either, and I'm too busy to stop and check everything the manual says, as I'm sure everybody else is.

If it's not true, then why do they all say it is?

AFAIK couple of other makes I am involved also don't say why

I have seen with my own eyes SR induced shake on a tripod. It was pretty impossible to mistake for anything else, it was a moon shot and the resultant double image (with SR at 500mm) was very impressive.

Now that is a comment I wanted to read. Coming from someone who has first hand experience. In that case I will take it for granted that SR kept on while on tripod does induce shake.

Pentax manual:

Ok, and how did you release the shutter in this case?

And if you want examples look at
link

Also see the K-x manual - bottom of page 129 where it gives a caution
Bolding is mine

I certainly learnt my lesson from that thread

Thanks for quoting the relevant bit, Gwyn.

However, what this does not say, is why they recommend you turn off the SR.

It certainly does not say "Turn the SR off, because you'll get worse results with it than without it."

I mean, we all know that even with the 3-4 stops improvement you get with SR, eventually you'll get to an exposure that is so long that it can't compensate enough to give you perfect sharpness.

What I'm looking for is either an 'official' statement from the manufacturer along the lines that the effect that John (and many others) allege is real, or some proper evidence from someone that's done a suitable experiemnt.

Well they don't, do they. They tell you to turn the SR off, absolutely, and for all I know, they have a good reason for it.

But AFAIK, they never say why, and now we have this story that goes around that alleges that the SR mechanism itself induces shake.

It's only this that I'm challenging.

Chris, this is the exact reason why I conducted an experiment, albeit with a non Pentax (sorry I didn't have any choice )

I was constantly forgetting my SR on when using the camera on a tripod. I am used to frequently change handheld to tripod and back again constantly even in the field. At times hand holding to shoot and occasionally sticking it on a tripod. And would be caught often with SR on after already a few shots taken. And when I would turn it off then suddenly handholding I would end up shooting a few frames with the SR off. Got sick and tired of that and decided to just leave it on all the time. And one day I went through the details of checking it up at home. Although non scientific but I tried to cover as many bases as possible, with the long macro lens I had, and also a long prime. My conclusion in the end: There was no difference between the shots taken on the tripod with SR on and off.
That was enough for me from then on to just leave my SR on all the time while in the field. Didn't want to risk catching myself shooting handheld with the IS, oops SR on.

But hey, this is just me, others might have a different experience, but just thought this might help someone who has been going through the same problems like me. May be I just eat too much cheese hence forgetting to turn the SR on when handholding if I have spent some time shooting with it off while on a tripod.

Let me expand a little on why I'm asking this...

If you release the shutter with any of the delayed modes, or with the remote (wireless, anyway, I'm not 100% sure about wired), then the camera turns the SR off anyway, regardless of the SR switch position.

If you release the shutter using your finger on the button, the situation is more interesting, cos there are two very clear effects that can be easily demonstrated:

The first is simply that using your finger will wobble the camera, no matter how careful you are, and this induces shake. I had a reasonably careful look at this on the K10D, and my conclusion was that if you press the button with your finger, it generates shake that the SR can't remove. But this shake was no more or less than the shake that ended up in the image if you did it with SR off.

So I'm not at all surprised that, if you pressed the shutter release button to take the picture with no delay, you saw some shake - especially at such a long focal length as 500mm.

What this does not, however, prove, is that it was the SR mechanism that generated the shake in the first place.

The second effect is that the SR has to be stabilised. If it's not yet stabilised (ie, hand symbol in the viewfinder), then all bets are off. Unstabilised SR is often a lot worse than no-SR, and of course, camera-on-the-tripod is one of those cases where we often don't look through the viewfinder at the point of shutter release.

So again, unless you took care to ensure that the hand symbol was showing, I wouldn't be surprised by any amount of shake.

Again, though, it doesn't prove that the SR system starts generating shake when there's none to detect.

As I always point out when I climb on this particular hobby horse, I have no axe to grind about this, and I'm more than willing to change my mind as soon as there's some good evidence.

Ahh I see what you're getting at. Hmm it was a long time ago, but I believe I was just using my finger (which is how I take almost all of my moon shots)

Really wish I'd saved those images!