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Old 01-04-2010, 03:19 AM  
rowan
Too lazy to set a custom title
 
Join Date: Mar 2002
Location: Australia
Posts: 17,393
Quote:
Originally Posted by xenigo View Post
If you want to do any serious photography of any kind, you need to have an L lens with a constant aperture. The last thing you need is your aperture changing from 4.0 to 5.6 because you zoomed, and it totally fucks your exposure. With one of the L 2.8 zoom lenses, you'll never have to worry about that.
I just had a quick look at the lens list and most of the L series telephotos are the same aperture at the wide and telephoto end of zoom range... the only exception seems to be the 100-400mm f4.5-5.6L IS USM

One other issue is where focus changes as you zoom, although that should be quickly fixed if you're in AI servo mode. (Even if you're not a quick half pump of the shutter will refocus...)

From memory there are several L lenses that are parfocal which means they don't need to be refocussed if they're zoomed.
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