[Rondec]

Thanks for the confusing welcome :-P My dilemma stemmed from the fact that while experimenting on SR capabilities of the K-r there were times when I couldnt tell if my "shake" was consistent across shots. And I couldnt figure out a way to measure the SR effect reliably.

Any views on how SR compares between say the K20d, K-r and K-5 ?

The biggest problem that I see with SR is that it takes a little bit to "spool up." It also isn't particularly effective if you are doing things like panning, tracking toddlers movements with your camera. It is probably at its best when you are holding your camera steady (as steady as you can) and taking a photo of a static scene.

I don't usually turn my SR off, but it is reasonable to do so in these other situations. Certainly you won't see a lot of benefit.

[Blue]

Don't blame me for the 1/(5*FL) rule -- blame Ansel Adams. See THE CAMERA, where he relates handheld shooting a 50mm lens at 1/50th and did NOT get sharp images, but at 1/250th he succeeded. If we assume that the average SR boost is about 2.5 f-stops, that fits exactly: With SR, use 1/FL. Without SR, use 1(5*FL).

And I've never seen any supporting data for a 1/(1.5*FL) ROT (rule of thumb) on APS-C. Doesn't mean it isn't there, just that I haven't seen it.

How I apply this: With AF lenses, I'm happy to let the SR'bot in my magickal K20D handle the work, especially if I have the Program Line set for Hi-Speed Priority. With MF primes, used in either Av or M mode, I'm also generally OK with the SR'bot -- I just diddle the aperture until I'm happy with the shutter speed. With MF zooms, I shoot in bright light with SR off, and I apply the 1(5*FL) ROT.
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But I digress. The question was: What's the logic correlating SR with f-stops? The answer has to do with EV equivalents. Opening the aperture by 2 stops allows a 4x faster shutter, which is also 2 stops. Each stop marks a doubling or halving of light reaching the frame, thus 1 EV (exposure value). Adding SR is AS IF the aperture or shutter were about 2.5 stops faster. So I can shoot a 50mm lens at 1/50th and SR will produce an image AS IF the shutter is at 1/250th. That's the SR equivalence.

Are you thoroughly confused yet? Good. Welcome to the madhouse.

Yeah, but he was using a LF camera half the size of his car. I always used the 1/FL as the bare minimum (without SR). However, with longer lenses, you can run out of aperture and/or ISO, fast.

[RioRico]

Don't blame me for the 1/(5*FL) rule -- blame Ansel Adams.

Yeah, but he was using a LF camera half the size of his car. :Hysterical:

Not handheld. #8-)

(Setup in question was a 35mm rangefinder with a 50mm lens.)

However, with longer lenses, you can run out of aperture and/or ISO, fast.

Quite so. I rarely use my Rubinar Makpo 1000/10 (1760g) handheld even at 1/4000. (For a bright object: ISO 1600.) And just wait till I put 10x of TCs behind it. Ooh ooh!

[patricklui]

So it mean with SR we got extra 1 or 2 stop of light or exposure?

Sorry for my poor english hahahaha

[steve1307]

So it mean with SR we got extra 1 or 2 stop of light or exposure?

Sorry for my poor english hahahaha

Well, you dont magically get extra light when the SR is switched on.
HA HA, Imagine if the Sun got brighter when you switch SR on! That would be great for a cold & rainy English winter.

What it means is you can shoot with a slower shutter speed 1 or 2 stops slower than you would without SR and still have a steady picture.
Slower shutter speed lets more light onto the sensor of course because it is exposed for a longer time.

[patricklui]

Well, you dont magically get extra light when the SR is switched on.
HA HA, Imagine if the Sun got brighter when you switch SR on! That would be great for a cold & rainy English winter.

What it means is you can shoot with a slower shutter speed 1 or 2 stops slower than you would without SR and still have a steady picture.
Slower shutter speed lets more light onto the sensor of course because it is exposed for a longer time.

ah hah ok i get it now, thanks steve.

[Marc Sabatella]

"SR" is subjective because "S" is subjective. Not everyone shakes the same amount or the same way all the time.

[bossa]

I was pretty amazed that I could take sharp pictures with my new Nikon 70-200 VR2 at 200mm for 1/13th second. Kinda sobering really.

[JimJohnson]

Thanks everyone. The logic is understood. My only gripe is - doesnt that make the measurement of SR very subjective ?

There is LOTS of subjectively in photography! For example, we often talk about depth of field / depth of focus. In reality, there is only ONE absolute point of focus, no matter what the aperture might be. What DOF really means is a range of acceptable focus. And like a lot of other things, acceptable is a subjective term. Lens with hyperfocal marks on the lens suggest that at a given aperture where the DOF will occur. Sort of. Same thing with SR and shutter speed.

If the difference doesn't make a difference to most viewers - the image is good.