[Sunday]

I am reading one must disable the shake reduction system when using a tripod. I understand it may not be necessary using the SR together with a tripod, but cannot understand why it should be disabled.
Does it affect the image? Can somebody explain in technical terms, other than "it's written in the manual"?

Thank you.

[Chaos_Realm]

I am reading one must disable the shake reduction system when using a tripod. I understand it may not be necessary using the SR together with a tripod, but cannot understand why it should be disabled.
Does it affect the image? Can somebody explain in technical terms, other than "it's written in the manual"?

Thank you.

Without knowing the full technical details of "how it works" I know the basic concept is that it detects vibration, and moves the sensor with oscillation calculated to counter the movement.
When SR is left on whilst on a tripod It basically introduces slight shake to the sensor as it is trying to find/compensate for shake that isn't there. But If you are ever using a tripod you should be using remote shutter or shutter delay. I know that even the 2 sec shutter delay automatically turns the SR off.
It should also be turned off when using techniques where blur is desired, eg panning technique.

Have a look at this HERE (post 9 & 11) for the results SR can have. The photos here were taken by a lens with Image Stabilization (IS) but it works on the same principles as SR.

I hope this covers in enough detail for you.

[billtin59]

Without knowing the full technical details of "how it works" I know the basic concept is that it detects vibration, and moves the sensor with oscillation calculated to counter the movement.
When SR is left on whilst on a tripod It basically introduces slight shake to the sensor as it is trying to find/compensate for shake that isn't there. But If you are ever using a tripod you should be using remote shutter or shutter delay. I know that even the 2 sec shutter delay automatically turns the SR off.
It should also be turned off when using techniques where blur is desired, eg panning technique.

I hope this covers in enough detail for you.

I know this is the accepted / "official" explanation for turning off SR when using a tripod, but to me it has never made sense. It implies that with SR on, the sensor is always moving regardless of camera movement! What if I have SR on and my hand held technique is such that there's no movement, will my shots then be blurred? How about SR with fast shutter speeds, will my shots be crooked due to sensor movement? Inquiring minds wanna know!

[gp1806]

I'm going to guess here. Back when I worked in a research lab, the control circuits that we used in our load frames had a small amount of electronic 'noise' in the feed-back loop. That is to say that the feed-back circuit could introduce a small false signal to the control circuit, causing the control to react to a deviation that didn't exist, we called this 'dithering'. This problem was most apparent when trying to hold a steady state, either load or extension. During dynamic operation, this was never a problem. I suspect that the Pentax SR does the same thing, electronic 'noise' will cause 'dithering' (sensor movement) in the steady state (no movement) that the tripod provides. I have no proof of this, only my take on a possible cause.

[billtin59]

I'm going to guess here. Back when I worked in a research lab, the control circuits that we used in our load frames had a small amount of electronic 'noise' in the feed-back loop. That is to say that the feed-back circuit could introduce a small false signal to the control circuit, causing the control to react to a deviation that didn't exist, we called this 'dithering'. This problem was most apparent when trying to hold a steady state, either load or extension. During dynamic operation, this was never a problem. I suspect that the Pentax SR does the same thing, electronic 'noise' will cause 'dithering' (sensor movement) in the steady state (no movement) that the tripod provides. I have no proof of this, only my take on a possible cause.

This may very well be the case, but the problem would STILL exist with steady hand held and / or fast shutter speed shots, would it not? If SR should be off for tripods, wouldn't there be other circumstances where SR should be off as well?

[Chaos_Realm]

I know this is the accepted / "official" explanation for turning off SR when using a tripod, but to me it has never made sense. It implies that with SR on, the sensor is always moving regardless of camera movement! What if I have SR on and my hand held technique is such that there's no movement, will my shots then be blurred? How about SR with fast shutter speeds, will my shots be crooked due to sensor movement? Inquiring minds wanna know!

for short focal lengths you might be able to but for long FL (200mm+) You'd darn near need to be made of stone to hold steady enough hand held for that to be an issue whilst shooting hand held.

as for the fast shutter speed as you can tell from the photos i linked to previously you can see a steady oscillation. I presume they were approx 1/2" and the osculations are visible (from possible feedback as pointed out above) so if you got to say 1/80 to 1/200 shutter (guessing) that should effectively freeze these osculations.

It would be interesting to see some test results on shutter speed for this too.

[billtin59]

you can tell from the photos i linked to previously you can see a steady oscillation

Sorry, but those photos aren't relevant to this discussion since they weren't taken with a Pentax camera. Different stabilization system.

[Chaos_Realm]

my thought process is that It works on the same principle though. But as I have stated earlier I don't know all the details on "how it works" but my logic tells in lens IS would work similar to SR but instead of adjusting the sensor, it would adjusts one of the glass elements in the lens to compensate for vibrations. the vibrations that the system generates when there is no external shake i would think is just caused by the components that they both have in common.. The gyroscopic sensor that detects movement and the algorithms which tell the sensor/element how it should compensate.

But I think this will be open for debate until someone looks up the patents of each. works out how both systems work and then find the source of the SR/ IS induced vibration.

[DogLover]

But If you are ever using a tripod you should be using remote shutter or shutter delay. I know that even the 2 sec shutter delay automatically turns the SR off.

The timer delay and the wireless remote will disable SR, using a cable release will not, however, so you should turn it off yourself if you are using this.

[DogLover]

I know this is the accepted / "official" explanation for turning off SR when using a tripod, but to me it has never made sense. It implies that with SR on, the sensor is always moving regardless of camera movement! What if I have SR on and my hand held technique is such that there's no movement, will my shots then be blurred? How about SR with fast shutter speeds, will my shots be crooked due to sensor movement? Inquiring minds wanna know!

It may not make sense to you, but it is a fact. Try it for yourself. Use a tripod and a long lens (to intensify the effect) and take some shots with and without SR on. The SR "on" shots will be noticeably less sharp (all other variables being equal) due to the SR trying to compensate for movement that isn't there. This is best done with a cable remote, which you may not have, but I do and have tried it. I assure you that you do not want SR on when a tripod is used.

[Pentaxosaurus]

This may very well be the case, but the problem would STILL exist with steady hand held and / or fast shutter speed shots, would it not?

I suppose that as for a hand-held shot the SR can still leave a visible error of a, say, 1-pixel blur, this is in most cases better than no SR at all. And not every hand-held shot is totally sharp, is it? The same could happen when using SR with a tripod, but then it's more of a nuisance as the blur wouldn't have been there without SR in the first place.

Therefore I think it's a good idea to turn SR off when the camera is on a secure rest just to cut out one possible source of (even a minute) error.

[billtin59]

my logic tells in lens IS would work similar to SR

I get what you're trying to say, but my logic tells me it's two different systems that achieve the same goal by using two different methods, thus the results and or shortcomings of each different system will be different.

[billtin59]

I suppose that as for a hand-held shot the SR can still leave a visible error of a, say, 1-pixel blur, this is in most cases better than no SR at all. And not every hand-held shot is totally sharp, is it? The same could happen when using SR with a tripod, but then it's more of a nuisance as the blur wouldn't have been there without SR in the first place.

Therefore I think it's a good idea to turn SR off when the camera is on a secure rest just to cut out one possible source of (even a minute) error.

Yeah, but is the difference that noticable? What about for fast shutter speeds, and let's for the fun of it consider the use of a monopod, then what??

Personally, I don't use SR at all, I spent many years shooting film without it and don't see why I need it now. Granted my hands aren't as steady as they used to be and the K20 is much heavier, but I rarely use long lenses OR shutter speeds.

[billtin59]

It may not make sense to you, but it is a fact. Try it for yourself. Use a tripod and a long lens (to intensify the effect) and take some shots with and without SR on. The SR "on" shots will be noticeably less sharp (all other variables being equal) due to the SR trying to compensate for movement that isn't there. This is best done with a cable remote, which you may not have, but I do and have tried it. I assure you that you do not want SR on when a tripod is used.

Just for chits and giggles, I tried this with my 50 - 200 zoom, took 3 pairs of shots zoomed in on cd's in a rack, all 3 sets look the same at "normal" viewing size, zoomed to 100% and there was a very minor difference in sharpness between the two, for all intents and purposes though, they were the same. I'd have to make poster prints before you'd notice!

[DogLover]

Just for chits and giggles, I tried this with my 50 - 200 zoom, took 3 pairs of shots zoomed in on cd's in a rack, all 3 sets look the same at "normal" viewing size, zoomed to 100% and there was a very minor difference in sharpness between the two, for all intents and purposes though, they were the same. I'd have to make poster prints before you'd notice!

No offense, but you may need a sharper lens than the 50-200, and you almost certainly need to be outside in sunlight, zoomed into something in the distance.