Quote (Antichrist- @ Thu, Apr 16 2009, 02:29pm)
When you use 200mm lens, you should use atleast 1/200 sec shutterspeed if no is, if you use is you can use about 3 stops slower shutterspeed, thats around 1/50of sec. If you use 1/50 sec with f-4, its the same light as 1/100 with f-2.8, but since you can use so slow shutterspeed without is, you get only half of the light(or need to use double iso with non is 2.8 version). Allso at 200mm f-2.8 has really shallow dept of field, so on meny situations you should stop it down a bit. Naturally 1/50sec doesent stop motion as good as 1/200 sec, but if some bird isnt moving 1/50 is enough for it, in those cases f-4 with is > f-2.8 without is, bt if you shoot sports for example, you dont do shit with is, you just need to stop the motion then 2.8 is better.
In what situations would you want to handhold a shutterspeed of <1/200 @ 200mm? A general rule is that you should use a shutterspeed of above 1/60 for anything that moves. Ideally over 1/100. If you were shooting portraits u'd want the 2.8 for bokeh. The only thing i can think the IS f/4 would be better for is shooting something perfectly still (like a landscape) on a non windy darkish day and i wouldn't use 200mm to shoot a landscape!!
I'm probably wrong so correct me
