So I just went out today to a nearby lake to test out my new EF 70-200mm f/4L USM. I realized as I was taking photos of birds that 200mm isn't quite long enough for this purpose. So major cropping was involved : (


My question was, the photos of wild life that were quite close (10-15 ft away) were not quite in focus. I was shooting ISO100 and +1/1000 exposure. Which made me wonder, if the lack of being able to use the center f/2.8 autofocus point had some significant effect?


I shoot with an ancient 300D Rebel so I wouldn't be surprised. But I've taken shots with my Tamron 17-50mm f/2.8 non-vc which have had far better focus seen at 100% crop...


Is this something that could be avoided if I just had a better AF on my camera? Would the difference be negligible at that focal length? Or is this the burden of having a maximum aperture of f/4...? If so I would return this lens in a heart beat, bite my lips for now and save up [:'(]


p.s - this lens was also a refurbished one...odd considering I found out after I bought it Adorama is selling a brand new one for the same price...?