Sunday, November 29, 2009

Focusing speed

I've two zoom lens: a Canon EF-S 18-55 f3.5-5.6 IS kit lens and a Canon EF 100-400mm f4.5-5.6L IS, and three prime lenses: Canon 50mm f1.8 II, Canon 100mm f2.0 and Canon 200mm f2.8L.

Interesting enough is that, both zoom lenses have IS. I found IS pretty useful when the ambient light is weak, for examples, for all indoor settings, or when the aperture is small. All my prime lenses have relatively big aperture and thus, even without IS, they work pretty good.

When we talk about focusing speed, IS couldn't help. In dimmer light, those prime lenses are really fast and accurate. And being prime, they are intrinsically faster in terms of focusing, and with the added aperture, they truely shine. Actually, IS could slow down the focusing process, since the focusing will not be done until after the stablizer works. So, in case you want faster focusing, switching off the IS mechanism will help.

I always think that prime lenses are better for creativity, but of course, the zoom are unbeatable for convenience.