Quote Originally Posted by neuroanatomist


I don't think a 70-200mm + 1.4x TC is the way to get to 280mm, and a 70-200mm + 2x TC is definitely not the way to get to 400mm. Compare the 70-200mm f/2.8 non-IS with the 100-400mm at 400mm f/5.6 (ISO 12233 crop link). The 70-200 f/2.8 non-IS plus 2x TC costs the same as the 100-400mm, lacks IS, and is quite optically inferior. The f/2.8 IS version + TC costs significantly more than 100-400mm, and still optically worse. The 70-200mm f/2.8 IS MkII + TC is even more expensive (pushing $1K more than the 100-400mm), and while the 70-200 II holds up better to a TC than any other 70-200 zoom, it's still not as good as the 100-400mm @ 400mm (although the MkII + 1.4x @ 280mm is as good as the 100-400mm @ 300mm - which is why I use the 70-200 II + 1.4x as a bird/wildlife lens when it's raining (but when it's dry, I use the 100-400mm).


An extender is useful if you only rarely need that focal length. If you regularly use a particular focal length (and for birds/wildlife, you will regularly use 400mm), then get a lens that natively covers that focal length (the few possible exceptions being the fast supertele primes, e.g. 300mm f/2.8L, 400mm f/2.8L, etc., which lose very little optical quality by adding a TC).



In the constraints of cost and quality, I think the 100-400mmm is certainly another good suggestion. I think that lens is really an over achiever, and I'm usually very surprised and impressed with the images that come out of it, however it's a little slow from 135mm and up. I think it's a good wildlife lens, but not as good for faster action. If he gets the 100mm-400mm then his kit will look like this:


50D, 17-55mm, 100-400mm and he has a big hole in his kit, from 55mm-100mm which is a slight problem.


We could play ISO Crop Chess:
  • Canon EF 70-200mm f/2.8 L USM Lens - Canon EF 100-400mm f/4.5-5.6 L IS USM Lens at 135mm and f/5.6
  • I didn't choose a larger and faster aperture, because the 100-400mm lens doesn't have them to match up correctly.



http://www.The-Digital-Picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=242&Camera=453&Sample=0&am p;FLI=3&API=3&LensComp=113&CameraComp= 453&SampleComp=0&FLIComp=1&APIComp=2


Essentially, I think you will agree that the 70-200mm will win in the 70-200mm range and the 100mm-400mmm will win in the 200-400mm range. The 1.4X will give him some versatility and you're right the 2x looks "not so good" on this 70-200mm Mk I lens. I also have the MK II which is at another level.


The choice really depends on what the majority of his shooting will be and where the sweet spot of his focal length needs to be. Does he need a faster shorter focal length or a longer slower length?


Can he live with a big hole in the 55mm-100mm focal range or will he need another lens to fill that gap?


I know for me the 70-200mm focal range is my favorite range.


Only Cytoman can answer those questions.


But I think we both agree that new glass is the way to go.


Rich