Which Lens??? 100-400mm L IS or 300mm f4 L IS???

The 300mm f/4 IS at 300mm with no 1.4X gives you a full stop more aperture than the zoom. But as soon as you put the 1.4X on, the zoom pulls ahead in image quality (and focus speed and bokeh, I bet):


ISO 12233 comparison of 300mm f/4 IS + 1.4X and 100-400 at 400mm


Therefore, if you plan to use a focal length of 300mm the most, and very rarely, if ever, use 400mm, then I would recommend the 300mm prime. Or, if it's more importnat to have f/4 aperture (and you'll live with shorter focal length to get it), I would again recommend the prime.


But for all other purposes I would recommend the zoom.

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Originally Posted by L33t

I like 300 more, it's faster and sharper.
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on it's own...maybe, but not at 420mm's.

Both are good lens.. I used them both but my favs EF300mm, because its prime and "solid"build.

what do you mean

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Originally Posted by L33t

what do you mean
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I assume that question was directed at me? If so, to answer it, the 300/4IS+1.4x TC (420/5.6) is a slower lens than the 100-400 when it comes to AF and is also outperpermed by the 100-400's IQ (specifically color/contrast). The only reason I see picking up the 300/4 is if the user is going to use it on its own more than not. For wildlife, generally speaking, the longer the reach the better off you are and since the 100-400 is a zoom it can counter with the ability to go 'wider' without the exchange or removal of a TC. All in all, the 100-400 is a much more versatile lens even though the 300 offers f/4.

I've had the 100-400 for a little while now, and while the 400 f/5.6 seems clearly better in terms of optical quality, the 100-400 zoom with IS is pretty handy, and the ability to go wide gets really handy in situations when you realize you otherwise couldn't back up enough.


Plus, if I happen to leave it on, even if it's not a multi-purpose kind of lens, it's a lot closer than a fixed.


I saw some light coming in and hitting a bowl, and the 100-400 wasn't the ideal lens I would have selected, but i could get by before the light passed. I grabbed it off the counter, and tried to hold myself still, and gosh darn it, it wasn't that bad, I think.


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Camera ModelCanon EOS 30D
Tv( Shutter Speed )1/20
Av( Aperture Value )5.0
ISO Speed800
Focal Length220.0 mm


A reallly long fixed lens is good for subjects which will likely stay far away, or are so small that you'l never really get close enough. Otherwise, though, you have to move so much to change the framing just a little, that running around just isn't practical, like you could do with 80mm and below..Plus, running backwards with your face in a view finder probably isn't the safest practice anyway.

Both are superb Lens.... my choice would be PRIME EF300mm F4/IS L