Originally posted by billtin59 I understand your theory, but I don't see any evidence of it in practice.
Yes, but have you actually tested for this effect? It could well be SR has been reduced to zero effectiveness (or worse) and you've just never noticed. If in controlled testing you have demonstrated that while setting SR focal length to 200 reduces the effectiveness of SR compared to setting it correctly, but that it does not actually make SR counterproductive, then great. I'm honestly curious, and would love to see test shots to document just how much of a difference it makes in situations like this.
I *have* tested it, and know for a fact the effect is real, but I admit I don't know how far you have to be off in order for it to actually be detrimental as opposed to simply reducing effectiveness. Like I said, the effect is extreme and obvious if you have it set for 200 when the actual focal length is 28. The only question is at what point does the effectiveness of SR drop to zero and start to become counterproductive. Could be when you are off by 2X, 3X, 4X, or something else - would be interesting to find out. But my money is on 2X.
Quote: I also see no mention of over / under compensation in the manual
They tell you to set the correct focal length; just because they don't spell out the consequences of not doing so doesn't mean anything. They don't spell out the consequences of doing a lot of things they tell you not to do.
Quote: if it were a real concern I'm sure there would be a warning as there is for turning off SR when using a tripod.
As I said, they *do* tell you to set FL correctly; they just aren't explicit about the reasons. So even without giving a reason, they'll told you what you are supposed to do. Whereas, without this warning, how you would you know you were supposed to turn SR off when on a tripod?
Anyhow, we can theorized all we like; the proof is in actual tests. Mine have proved absolutely conclusively that the effect is real; the only question is how far you have to be off before it's makes SR counterproductive. Only testing would tell us for sure.