70-200mm used or new, 2.8 IS or 4 IS

[BokChoiTV]

So my budget is around 1300$.
I just got a MkIII and mainly do video, still do pictures occasionally, but main focus is on videos.
Should I get a new 70-200mm F4 IS which is around 1200$ new
or get a used 70-200mm F2.8 IS (Mk i), which is average 1300$?
I only have a 50mm 1.4 atm.
Is the extra speed worth it? I mainly do videos outdoors, but will do indoor sometimes.

[rs]

It depends on what sort of depth of field you're after. If you were doing stills, there's very little point as the extra size/weight of the 2.8 IS mk I is only there to get you an extra stop, and that lens really isn't sharp enough to warrant using f2.8. But 1080P is only 2MP, so even the mk I lens will deliver for video at f2.8.

When it comes to shutter speed in video, you'll probably find yourself using an ND filter to slow things down outdoors when you want to use a shallow depth of field with either lens. On the occasions where you do shoot indoors, f2.8 could come in handy - but with such good high ISO capabilities of the 5D3, its not a necessity.

[bycostello]

i'd go for the f2.8 as i like to shoot wide open

[crasher8]

I have to tell you I thought long and hard about the 70-200 choices to go with my 5D3. I previously had a 70-200 f/4 and have tried and rented/borrowed all variants being sold new in the past year. After the lens prices went up Feb 2nd I decided to try the Tamron 70-200 2.8 VC. I think it beats all Canon versions except the 2.8ISii in AF speed, color rendition, contrast and corner sharpness. Bokeh is gorgeous and it's lighter than Canon's comparable model. It only falls to the big boy at 200 in the corners.
$ 1499 with a 6 year warranty. Maybe rent one from lensrentals.com.

[BokChoiTV]

Since I have a full frame, will the DoF difference between 2.8 and 4.0 that different?
Also I found that a used 70-200mm F4 IS is around 900, making it around a 400$ difference between 4.0 and 2.8.
;__;
Agh, this is hard.

[RS2021]

It depends on what sort of depth of field you're after. If you were doing stills, there's very little point as the extra size/weight of the 2.8 IS mk I is only there to get you an extra stop, and that lens really isn't sharp enough to warrant using f2.8. But 1080P is only 2MP, so even the mk I lens will deliver for video at f2.8.

When it comes to shutter speed in video, you'll probably find yourself using an ND filter to slow things down outdoors when you want to use a shallow depth of field with either lens. On the occasions where you do shoot indoors, f2.8 could come in handy - but with such good high ISO capabilities of the 5D3, its not a necessity.

+1

F4 is a very portable package and delivers great video even in low light.
Here is an indoors video filmed with the 70-200 f/4:
http://m.youtube.com/watch?v=0IKSFBaG8ZY

[RS2021]

He used a 5D mark II then for that video. I would guess 5d3, if anything, would be better.

[Halfrack]

70-200 2.8 non-IS - It's a parafocal lens - which means if you set your focus, and zoom, you stay in focus. 

http://www.lensrentals.com/blog/2011/02/photo-lenses-for-video/4

[East Wind Photography]

forget the 70-200 IS unless it's the MKII.  The first IS model was very soft.  The 70-200 F4L is incredibly sharp and comes darn close to equaling the 300 2.8L in sharpness.  I traded in for the 70-200 Mkii as I didn't need two of them or I would have still been using the F4 version.

[Menace]

70-200 f4 is a great lens. Recommended