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11-28-2008, 04:12 PM   #1
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Shake reduction at high shutter speeds

You may not think that you need shake reduction at high shutter speeds, but I hand hold a 500mm mirror lens on a K10D. On the basis that it's equivalent to a 750mm lens, without SR I would be thinking of 1/750th minimum, preferably 1/1000th shutter speed.

From much of what I have read, using SR seems to be little understood, but I will ask anyway if anyone knows if SR is effective at high shutter speeds. I can easily get camera shake at 1/750th if I am not really careful, but I am not convinced that the SR has much effect on this. I had one shot that was completely blurred (motion not focus) with SR on taken at 1/1000th. I am wondering if this shot was taken before the little hand appeared though and might be blur induced by the SR system.

Most people seem to test SR with slow shutter speeds and standard lenses and maybe SR works great at 1/15th, but does it react fast enough to be useful at fast shutter speeds? I have tested but my tests have been inconclusive.

11-28-2008, 04:34 PM   #2
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I can't answer your question because I own nothing above 300mm. I will say that I would not even attempt shoot 500m+ without at least a mono-pod. There is just so much a camera can do.
11-29-2008, 01:41 AM   #3
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oooh... my brain.... I'm going to take a wild guess, mostly because I want somebody to jump in and correct me.
The sensor has to move more, the longer the lens. At some point it's going to be too much. I don't think the shutter speed has anything to do with it, since even on a slow exposure, the sensor has to be moving when the exposure starts. But, if the sensor has to move more, it will have to move faster too. And that could be a problem also. I wouldn't doubt.. and I guessing again... That head movement would be harder to correct than camera shake. The logic behind this reasoning is you have to put in a focal length. So, the SR must be sensing the movement of the camera and compensating. So I would say, plaster the camera against your face, and keep your head still for the best results from SR. That way, any axial movement can be sensed by the camera.


QuoteOriginally posted by kevbirder Quote
You may not think that you need shake reduction at high shutter speeds, but I hand hold a 500mm mirror lens on a K10D. On the basis that it's equivalent to a 750mm lens, without SR I would be thinking of 1/750th minimum, preferably 1/1000th shutter speed.

From much of what I have read, using SR seems to be little understood, but I will ask anyway if anyone knows if SR is effective at high shutter speeds. I can easily get camera shake at 1/750th if I am not really careful, but I am not convinced that the SR has much effect on this. I had one shot that was completely blurred (motion not focus) with SR on taken at 1/1000th. I am wondering if this shot was taken before the little hand appeared though and might be blur induced by the SR system.

Most people seem to test SR with slow shutter speeds and standard lenses and maybe SR works great at 1/15th, but does it react fast enough to be useful at fast shutter speeds? I have tested but my tests have been inconclusive.
11-29-2008, 07:50 AM   #4
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I also have a 500mm mirror and since I don't own a tripod all my shots are handheld. I've never felt that shake was a big problem at least when shooting under daylight. Never switched SR off either so I can't say how much of a difference it makes. So I'll guess it is effective.

Also, some 500mm mirrors don't actually have 500mm focal length. You should try setting the camera to 450, 550, 600, 650 and see if you get better results.

11-29-2008, 10:28 AM   #5
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For these kind of length lenses, perhaps you should consider additional support, i.e. monopod, tripod, bean bag or something, just to help out a bit.

A slight movement at the camera end, can be a damned long way at the subject end.
11-30-2008, 04:26 AM   #6
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Good point about checking the actual focal length of the lens. This could make a consistent small difference. However, theoretically even if the focal length is 450mm and I have set it to 500mm, the SR should still help.

Yes I have used a tripod in the past (it's broken at the moment) and I do use beanbags, but there isn't always anything handy to rest them on when you're in the middle of a field etc.

The reason that I think the shutter speed may be important is that there is probably a small time lag between the movement and the SR correction. For a slow wobble as seen in a wide angle or normal lens, if the SR starts to kick in after say 1/500th sec with camera set at 1/30th, then only a very small movement will have occurred prior to the correction. But of course if the shutter speed is set to 1/1000th then the SR wouldnt have even started to correct before some or all of the picture has been taken. With focal plane shutters I suspect that the curtain might be part way across when the SR starts working?

Also the idea of switching off SR when using a tripod must be assuming that the tripod is really rock steady, but when I have used a tripod and long lens in a bird hide with people moving around, the thing shakes like mad and I hoped that the SR would stop that affecting the pictures.

Incidentally, other people have queried the switch off SR on a tripod idea where they have failed to find any evidence that SR induced shake rather than prevented it under those circumstances.
11-30-2008, 10:15 AM   #7
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QuoteOriginally posted by kevbirder Quote
Incidentally, other people have queried the switch off SR on a tripod idea where they have failed to find any evidence that SR induced shake rather than prevented it under those circumstances.
This is the one point where I suspect the SR system itself might induce movement.

However the "best" way to find out is to do an experiment yourself -
take some shots of a known stationary target - with enough detail/definition that you know will make a difference if there is shake, and literally do a series of alternate shots with SR on and off at the same shutter speed and see if you can see any difference?

Strictly speaking, this is only valid for your shooting (since the way I shoot, my habits may be different to yours) - although it will obviously be of general interest.
11-30-2008, 11:12 AM   #8
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QuoteOriginally posted by kevbirder Quote
...

The reason that I think the shutter speed may be important is that there is probably a small time lag between the movement and the SR correction. For a slow wobble as seen in a wide angle or normal lens, if the SR starts to kick in after say 1/500th sec with camera set at 1/30th, then only a very small movement will have occurred prior to the correction. But of course if the shutter speed is set to 1/1000th then the SR wouldnt have even started to correct before some or all of the picture has been taken. With focal plane shutters I suspect that the curtain might be part way across when the SR starts working?

...
It takes about 1/180th of a second to expose the frame no matter what shutterspeed at or above 1/180s is set. At 1/500s, for example, the shutter works like a narrow slit that travels across the sensor in about 1/180s. Each part of the sensor is exposed for only 1/500s thanks to the slit, but it takes 1/180s before the entire frame has been exposed!

I don't know how that would affect your logic, though, but I thought it was worth mentioning.

11-30-2008, 07:19 PM   #9
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I have shot an 800 mm mirror handheld and got decent results. Somethimes the handheld shots were sharper than on a tripod (lens has no tripod socket of its own). Some shots were higher speed some below 1/100. Don't think fast shutter turns off SR. Ole seems to be on the right track.
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11-30-2008, 08:14 PM   #10
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I don't think there is a lag with SR. Once the little hand light up in the viewfinder, the SR is active and compensate movement continuously. Of course, it cannot compensate for any movement, or else we wouldn't need tripods at all. But it compensantes enough that we can hand held a lens for 2-3 stops below what is usually recommended. This usual recommandation shows that SR and shutter speed are linked. Sure it's more difficult to correct shake for a 500mm lens, but you have to correct it for about 1/100s to reach the 2-3 stops gain. For a 50mm it would be 1/10s. The sensor has travelled the same distance in these 2 cases, it just did it faster in the case of the 500mm lens. That's maybe where SR maybe limited, if the motors cannot move the sensor fast enough.

Anyway it's not difficult to test. Shoot some pictures with SR on then off. It's easy to see the difference.
11-30-2008, 09:40 PM   #11
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Ole, I read that post of yours earlier today and I've been mulling it over ever since. Really something to think about there....

<==(* continues mulling *)
12-01-2008, 06:36 AM   #12
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QuoteOriginally posted by ManuH Quote
Anyway it's not difficult to test. Shoot some pictures with SR on then off. It's easy to see the difference.
Actually I AM finding it difficult to test which is why I started this thread. Have you in fact tried this with a very long lens hand held? The biggest problem is that the results are inconsistent, some showing massive amounts of shake even at high shutter speeds and with SR on.

There are many variables with this testing including focus which is very difficult to get spot on and can be difficult to tell from shake. Ideally you wouldn't adjust the focus between tests, but you are holding the focusing part of the lens and a tiny twitch of the fingers is enough to put it out. I have taken some more pictures today which I will analyse later, but it won't surprise me if the results are again inconclusive.
12-01-2008, 09:50 AM   #13
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QuoteOriginally posted by kevbirder Quote
The biggest problem is that the results are inconsistent, some showing massive amounts of shake even at high shutter speeds and with SR on.
Sorry to state the obvious - this in of itself may be telling you something -
that your shooting settings are not allowing you consistent results -
whether SR is On or Off.

May I suggest you take a few test shots with the camera/lens on some solid support (tripod or set firmly on a solid surface/bean bags) with the SR On and Off? (SR is automatically Off using self-timer) and see if you get more consistent results?
12-04-2008, 09:22 AM   #14
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QuoteOriginally posted by kevbirder Quote
Actually I AM finding it difficult to test which is why I started this thread. Have you in fact tried this with a very long lens hand held? The biggest problem is that the results are inconsistent, some showing massive amounts of shake even at high shutter speeds and with SR on.
I'll try for the fun of it with my FA80-320. Note that with the K20D it's easy to see the effect of SR with liveview.
12-04-2008, 09:35 AM   #15
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QuoteOriginally posted by Ole Quote
It takes about 1/180th of a second to expose the frame no matter what shutterspeed at or above 1/180s is set. At 1/500s, for example, the shutter works like a narrow slit that travels across the sensor in about 1/180s. Each part of the sensor is exposed for only 1/500s thanks to the slit, but it takes 1/180s before the entire frame has been exposed!

I don't know how that would affect your logic, though, but I thought it was worth mentioning.
Doesn't that defeat the purpose of 1/500 shutter speed setting?
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