70-200mm f2.8 L IS USM or 100-400mm f4.5-5.6L IS USM

[neuroanatomist]

I think you'll be better off with the 100-400mm lens.


IMO, using a 2x teleconverter is never a good idea - image quality suffers too much. If you look at [url="http://www.The-Digital-Picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=113&Camera=453&Sample=0&am p;FLI=7&API=1&LensComp=103&CameraComp= 453&SampleComp=0&FLIComp=6&APIComp=0]Bryan's ISO 12233 comparison of the 100-400mm to the 70-200mm f/2.8 IS + 2x Extender[/url], you'll see what I mean - the 70-200+2x is noticeably softer.


A 1.4x extender has much less of an impact on image quality than a 2x, but it's still an impact. When combined with a very sharp lens like a supertelephoto prime or the 70-200mm f/2.8L IS MkII (which is sharper than the MkI version), the 1.4x is a fairly good option. If you compare the 100-400mm at 300mm with the 70-200mm f/2.8 IS MkI at 280mm, the 100-400 is sharper with the 70-200mm at f/4 (and it's a stop faster), but at f/5.6 they are similar. The 70-200mm f/2.8 IS MkII + 1.4x at f/4 is actually as sharp as the 100-400mm where the ranges overlap, and it's a stop faster too. But the MkII version of the 70-200mm zoom costs substantially more than the MkI version.



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[quote=tylermartin]i felt i wasnt getting enough reach with my 55-250 so would the 1.4x make the quality much worse?[/quote]
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The IQ of the 70-200mm f/2.8 IS MkI + 1.4x will be a little better than the EF-S 55-250mm, but not much. 280mm is not significantly longer than 250mm. If you feel that you can't get close enough with a 250mm lens, a 280mm lens isn't really going to help you.


The only downside to the 100-400mm is that out at the long end, it's f/5.6 which is fairly slow for stopping action unless it's a pretty bright day. Since your 55-250mm is also f/5.6 at the long end, you will know what to expect there at least. The only longer+faster options are the supertele primes, which run several thousand dollars.


Personally, I use theEF 100-400mm f/4.5-5.6<span style="color: red;"]LIS USM for wildlife and birds, and theEF 70-200mm f/2.8<span style="color: red;"]LIS II USM mainly for family shots on trips, in the yard, etc. If I'm going out to shoot wildlife/birds in the rain, I'll use the 70-200 II + 1.4x extender, since that combo with my 7D is weather-sealed. But on dry days, I'll choose the 100-400mm over the 70-200 II+1.4x when I want reach.

[Brendan7]

I second what Neuro said except...

IMO, using a 2x teleconverter is never a good idea - image quality suffers too much.

I will point out that the 300mm 2.8, 400mm 2.8 and 500 4 primes are superb with 2x TCs, especially stopped down one stop. I used a 500 f/4 with a 2X TC at f/8 and f/9 and the results were superb. BTW - Why doesn't Canon make a 1.7X TC like Nikon? [:^)]


But since the OP isn't considering a $8000 lens, I suggest that he choose purely based on focal length and which he prefers.

[Keith B]

If you don't need the fast aperture, the 100-400 is way more versatile and I don't think you sacrifice much IQ.


I use my 100-400 way more than my 70-200 2.8 IS. The only time I use 70-200 lately is indoor events.

[ShutterbugJohan]

I faced the same dilemma and bought the 70-200. The fast f-stop and low light capabilities were more important to me than the reach was. If you are more concerned about reach than low-light ability, I'd recommend the 100-400. It is an outstanding lens.