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05-10-2009, 12:26 AM   #1
emr
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SR and steady position of the camera?

Now this may be a silly question. The general advice is that when using a tripod one shouldn't use the SR. Has someone actually done careful comparisons with SR on and off? And as a further question on the topic, if SR is bad with a tripod - how steady can the camera be so that SR is still adviced to be on? For example when the camera is hand-held but is held against a wall or some other stabilazing object?

05-10-2009, 04:34 AM   #2
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OK, not exactly a controlled double-blind experiment, but: I put my Kenko (Hoya) circular fisheye adaptor onto my SMC Pentax-M 40-80, set at 43mm (full fisheye circle). I mount this on my K20D, with SR set for 40mm. I place these on a sturdy table, and switch on Live View. The circular LV image jumps about like a spastic gerbil. This is an extreme case, but it's what happens. I've read reports, with a light lens and mounted on a light tripod, of the K20D's SR movements actually making the tripod walk around on a smooth floor.

IIRC, with SR, the sensor is bouncing back-and-forth, up-and-down, in a magnetic field, to counter the motion of your shaky hands. If the camera is not shaking, that sensor motion occurs anyway. If you're holding the camera against a wall or tree or whatever, turn off SR. If the camera is physically stabilized, turn off SR. But try it yourself.
05-10-2009, 09:50 AM   #3
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I too, have not done a rigorous study, but my experience has been that tripod shots with SR on lack the expected sharpness, while I am generally satisfied with the results with SR turned off.

Steve
05-10-2009, 10:01 AM   #4
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QuoteOriginally posted by emr Quote
Now this may be a silly question. The general advice is that when using a tripod one shouldn't use the SR. Has someone actually done careful comparisons with SR on and off?
I have, with the K10D.

I reported in some detail on the UK Pentax forum in this thread.

I found no evidence to support the often-quoted assertion that SR causes blur with tripod-mounted shots.

I observed no difference in shake with SR on or off, and concluded also that the amount of shake caused by releasing the shutter with a finger on the button is too small for SR to improve.

Finger-induced shake is very obvious, however, with moderately slow exposures, and the only way of getting rid of it is to use one of the remote or delayed modes, all of which switch SR off, regardless of the SR switch position.

05-10-2009, 10:09 AM   #5
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QuoteOriginally posted by ChrisA Quote

...use one of the remote or delayed modes, all of which switch SR off, regardless of the SR switch position.
Sort of makes you wonder why they do that...


Steve
05-10-2009, 10:31 AM   #6
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QuoteOriginally posted by stevebrot Quote
Sort of makes you wonder why they do that...
It does, and I know the manual recommends SR off on the tripod, although it doesn't say why.

I'm not attempting a definitive statement one way or the other, all I'm saying is that with a careful experiment, I saw no evidence of SR-induced shake.

I've also seen no account of a careful investigation by any that claim to have observed SR-induced shake.

Lots of things cause out-of-focus pictures, and for me, the anecdotal accounts that I've read are not rigorous enough to exclude those things.

Another member of the UK Pentax forum has presented quite convincing evidence that pictures taken before SR has had a chance to stabilise are often worse than with no SR at all, but that's a different issue.
05-10-2009, 10:38 AM   #7
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Thanks everybody. It seems the SR question is quite multi-faceted. I've personally wondered if my camera's SR works at all since pixel-peeped hand held taken photos don't always seem to differ whether SR's on or off. But perhaps the benefit is more obvious in different circumstances, with longer exposure times etc.
05-10-2009, 10:49 AM   #8
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QuoteOriginally posted by stevebrot Quote
but my experience has been that tripod shots with SR on lack the expected sharpness, while I am generally satisfied with the results with SR turned off.
Another thought, in the context of this comment.

On a tripod, we tend to know that there's no excuse for a lack of sharpness, so our expectations tend to be high. Whereas, hand-held, our expectations are lower, and indeed you'll often see people caption their photos as 'hand-held' if they're unexpectedly good.

The fact is that finger-induced blur on the tripod is almost impossible to eliminate, with or without SR, if you don't use a remote or a mirror-up delay.

It may be that it's this finger-induced shake that people see, and interpret as SR-induced, when actually it's the same as with SR off.

I just wish Pentax would be specific about why they make the SR-off recommendation.

05-10-2009, 11:14 AM   #9
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this may fly in the face of conventional wisdom, but...

SR enabled, tripod, 1/100 sec. in heavily overcast, windy conditions. No sharpening (except ACR defaults when converting from RAW). Taken with 300/2.8 + Tamron 1.4x MC4 TC = 420mm:


Crop:

EXIF

Even on a longer focal length setup with a tripod, I am not sure if this is simply solid technique or perhaps the SR is helping a bit. I am very, very strict on my technique when not using a cabled remote so it has more been a DOF issue for me that camera shake due to pressing the button. I squeeze rather than press/push the shutter button, plus I use my face and left hand to steady the camera and lens respectively.

I've had repeated success between 1/90 to 1/200 sec. shutter speeds at 300mm....

Personally I believe image sharpness and your success in technical excellence is more technique driven than anything else.

Regards,
Marc

Last edited by Marc Langille; 05-10-2009 at 11:32 AM.
05-10-2009, 11:23 AM   #10
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QuoteOriginally posted by Marc Langille Quote

Even on a longer focal length setup with a tripod, I am not sure if this is simply solid technique or perhaps the SR is helping a bit. I've had repeated success between 1/90 to 1/200 sec. shutter speeds at 300mm...
Mark,
I have often wondered the same thing. I seldom shoot with longer lenses (I lack a "tele-eye"), but it seems that SR would be useful under the conditions you mention above.

Steve
05-10-2009, 11:33 AM   #11
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QuoteOriginally posted by stevebrot Quote
Mark,
I have often wondered the same thing. I seldom shoot with longer lenses (I lack a "tele-eye"), but it seems that SR would be useful under the conditions you mention above.

Steve
Steve, perhaps this will help?

To further put my claim in perspective about solid technique, here's an image at 1/400 sec. with the Sigma 500mm. There is NO optical stabilization (Canon 40D with Sigma 500/4.5). It is an overcast day, subject in a shaded area:


Regards,
Marc
05-10-2009, 11:34 AM   #12
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I've formulated a theory (more of a guess really) about this based on some observations I've made and here it is in all it's wrongness...

A tripod mounted camera will move in a much different manner than a hand held camera. Specifically, it will oscillate rhythmically rather than the rather haphazard movements caused by the inability of a person to hold their hands mechanically still. This of course varies from situation to situation, but given a heavy lens on a underclassed tripod, you can see camera/lens combo oscillate if you tap it (yes I've ordered a better tripod - it's being shipped).

Obviously, the movement of the sensor exerts an equal and opposite reaction in the camera body, and if the tripod allows this force to create movement to some extent, it will of course blur the photo, but it may also create a feedback loop with the sensor trying to compensate for the sensor-induced shake. I've seen (heard) this happen with the camera+Bigma on a weak tripod and it sounded like my camera had turned into a reciprocating saw ("sawzall") - rapid strong vibrations (I thought my camera had died - then I remembered to turn off the SR...) Using proper long lens technique (eye pressed to eyecup, hand on lens above the tripod collar, etc.), dampens vibrations like this and allows for sharp shots even if you forget to turn of SR like I did yesterday (doh!)... Check it out (and it's sharp when pixel peeped too)...


So, there you have it - my theory - Undampened oscillations are increased by a feedback loop between the camera/lens combo and the sensor's movement... Given a smaller setup, say just the camera and a small lens on a beefy tripod but not held or dampened by hand, this sort of thing might not create the full-on feedback loop which caused the mad-wasp buzzing of the sensor, but could still cause more shake than just mirror slap would have... I dunno know if I'm right, but that's all I've got .
05-10-2009, 11:44 AM   #13
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I'll add to your comments about long lens technique: I don't just do the eye to eyecup! When shooting, it's pressing my face to the camera back...

BTW Josh, you will receive an invite to the exclusive "official photographer of the ugly club" in the mail soon... I have the inside resource to prove it:


Cheers,
Marc
05-10-2009, 01:00 PM   #14
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QuoteOriginally posted by emr Quote
I've personally wondered if my camera's SR works at all since pixel-peeped hand held taken photos don't always seem to differ whether SR's on or off. But perhaps the benefit is more obvious in different circumstances, with longer exposure times etc.
I'm not sure what conditions you tested under, but in the situations where SR works, you don't need to pixel peep to see it - it's obvious on the LCD even without zooming in. Try shooting at 200mm with a 1/20" shutter speed, SR on versus SR off.

Do note that even when SR is on, it isn't *really* active until a fraction of a second *after* half-pressing shutter (at which point you see the "hand" icon in the viewfinder. If you're in the habit of just punching the shutter button rather than half-pressing first (to focus and set exposure, for example) and then finishing pressing when ready, you probably haven't actually been getting the benefits of SR. I believe the Pentax Photo Browser software will tell you if SR was actually in effect or not. [ EDITED: originally I wrote "if you're *not* in the habit..", which is the opposite of what I meant! ]

Last edited by Marc Sabatella; 05-10-2009 at 07:36 PM.
05-10-2009, 01:16 PM   #15
emr
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QuoteOriginally posted by Marc Sabatella Quote
...
Oh. I tend to have the habit of half-pressing first and then finding the right composition and moment. Gotta try the direct approach.

Last edited by emr; 05-11-2009 at 10:18 AM.
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