“Is a tripod really necessary for a 70-200 mm zoom lens? One friend says yes and another claims that an image stabilizer makes a tripod unnecessary. My question is, exactly how effective is an image stabilizer? Most lens reviews seem a bit vague about that.”—R.Q.
An image stabilizer—in the lens or in an Olympus, Pentax or Sony D-SLR body—certainly compensates for camera shake to some extent but there is no simple answer to the actual effectiveness. The technology used by each manufacturer differs and even within a single brand, it’s more effective with certain lenses than with others. Additionally, because people vary significantly as to their own stability, the benefits of an anti-shake system can differ depending on the user.
One way to determine the effectiveness of the system in your own equipment is to read several test reports; you should be able to find many using a Google search. Many, though not all, reviewers do comment as to their own findings re: stabilizer effectiveness. Granted some people are simply more steady than others but the reviews should at least provide some indication as to what you might expect.
One Web-site, SLR Gear, uses particularly impressive standards in their stabilizer testing. They promise that the data they provide for all such devices (whether in a lens or a camera body) will be both reliable and consistent. Their methodology certainly seems valid and SLR Gear has an excellent reputation for their high level of credibility re: lens test reports.
So far, they have tested stabilizer effectiveness for only three 70-200 mm f/2.8 lenses, the Canon 70-200 mm f/2.8L IS II the Sigma 70-200 mm f/2.8 EX DG OS HSM APO and the Sony 70-200 mm f/2.8; the latter was tested with the Sony a55 D SLR with an in-camera system. Even if you own some other brand these three reports should give you at least an indication as to the level of effectiveness that you might expect with your own equipment.