I was talking with ms_danson about  the lenses I had purchased and planned to upgrade and hit upon a way to explain what image stabilization (IS) does to gamers.

Imagine that a zoom lens has a range penalty such that a 60-mm is a +0, 125-mm is +2, 250-mm +3, etc., each range penalty corresponding to an f-stop. IS acts like a modifier to counter range penalties up to +3, so a 50-250 mm zoom lens set to maximum zoom has a penalty of -3, but turn on IS and it shoots with no penalty. It generally ends up being a good idea to put points into IS to offset the range penalty because the situation comes up so often.

Below 60-mm, there are different modifiers so the IS bonus is situationally dependent. You can put points into purchasing the IS bonus, but don't expect to use it as often.

I've posted a story to provide background for a character I will be playing ms_danson's upcoming game.

http://community.livejournal.com/ratcatchers/36104.html

It might be confusing without context so consider yourself forewarned.