Stabilizing Lenses

I've been noting the exhuberance of Yaamon with the use of his 70 mm - 200 mm F2.8 IS II lens.

Alas, I only have one stabilized lens as I purchased most of my glass in the pre-IS era and the lenses cost too much to replace. And they still are useful.

I have been using for most of this year a full-frame camera (5D Mark II) and my stabilized lens is a 120 mm - 400 mm Sigma (not a push-pull Canon).

Recently (about 9,000 photos ago), I switched to a 7D, primarily to obtain more reach. The 1.6 lens factor effectively gives this lens a reach of 640 mm at F5.6. I have a suspicion, but haven't tried to test it experimentally, that the stabilization is less effective when measured in "stops" with the 7D than with the 5D.

Virtually every review of these lenses suggests that they yield a "X" stop improvement WRT shake.

It's never clear if this metric is dependent upon the camera used. Is it the same for a 7D versus a 5D? Obviously one could pick a body, then turn the stabilizing off and on to get an idea of the gain from the stabilization. The question, though, is whether or not this metric depends upon the body chosen.

Moreover, if one adds a teleconverter to the mix, how is the stabilization affected? My intuition suggests that the stabilization is affected by the camera body and the use of teleconverters, but I have no idea by how much.

Similarly when I switched bodies, my 600 mm became effectively a 960 mm lens. My stabilization with this lens is a monopod and I have noticed that I must be more careful when steadying the gear prior to a shot. That is, I think that 960 mm is about the limit (for me) when using a monopod as a stabilizer.