
Someone posted earlier something along the lines of
I was merely pointing out how that statement is not true. "faster" refers to the size of the aperture at maximum. The ability to let in more light, by use of a wider aperture. That being available is what determines "faster." The fastness to which an image is exposed on the sensor.
4 Stop IS does make the lens more useful in low light, but it does not make it "faster" by any means.
I was never de-bunking the awesomeness of the lens.
I was just correcting a hastily made comment, which was inaccurate. And, if read by anyone whom did not know of IS's fallback of not stabilizing moving subjects, would be false information.
I was making a simple "footnote" per-se, to the statement I quoted in bold.
Again gaining one stop of light makes your camera/lens one stop faster than if you didn't gain that one stop. Whether its one stop more sensitivity (ISO 3200 to 6400), one more stop stutter speed 1 second to 2 seconds or one more stop f/2 to f 1.4. All of those examples show gaining one more stop of light. And again I never brought freezing motion into the conversation. I've only been talking about camera motion when hand holding To be able to hand hold consistently a 200mm lens at 1/25 of a second is amazing. Thats a 3 stops of light advantage in a real world example. You should probably hand hold a 200mm without IS at 1/200 of a second (to minimize camera motion) and 1/25 of a second is gaining 3 stops of light. 200 to 100 is one stop. 100 to 50 two stops and 50 to 25 is 3 stops and again I'm talking hand holding and camera movement but its real. I could never hand hold a 135L and get consistent results at 1/25 of a second.