Like many people my decision on a telephoto zoom lens came down to buying the Canon 70-200mm f/4L or the Canon 70-300mm f/4-5.6 IS USM. I read a bunch of reviews and decided to go with the former. It is true that user comments and ratings in a variety of websites are slightly more favorable for the L lens. The 70-300mm has an improved IS and of course a longer focal length.
Upon trying the L lens handheld a few times, I was initially disappointed. Of course I knew I’d have to compensate the lack of IS with higher ISO, but in the field tests, it proved to be more difficult than that. Photos of flowers or birds in the shade demanded ISOs as high as 800. And that crippled the quality of the photo a little bit more than I would’ve liked. To avoid camera shake you need to shoot at the reciprocal of the focal length or faster. Sounds simple but with a Canon 50D you need to consider the camera’s 1.6 multiplication factor. So at 200mm you need a shutter speed of 1/320 or faster. I thought that I would be able to handhold at 1/200. But reality knocked in and showed me I couldn’t do it.
Another thing that may be a problem (it was for me in a couple of situations) is when you need to go unnoticed when shooting. The L lens makes it hard to do. It is white and big and people will look at you.
Still I have some mixed feelings about my decision. When the light is good this is a fantastic lens but with the IS feature offered on the 70-300mm I would probably get photos that I will miss with this lens. So I’ve decided to go ahead and get myself a Canon 70-300mm IS. It is arriving in a few days. I don’t like to have to use a tripod all the time and the 70-200mm forces me to do so when I’m shooting in the shade, which is often.
I can’t fault the performance of this lens for its limitations and I have given it 5 stars. In other words it does what it is supposed to do very well but my message to other buyers is to consider where you are most likely to use the lens before buying. Remember IS becomes increasingly important as you extend the focal length.
Conclusion: Well, IS would be nice for those low-light 200mm hand-held shots. Otherwise, this lens is nearly perfect in build quality and most importantly, image quality. It is ultra sharp with eye-popping contrast and accurate colors wide open at f4.0 over the whole range from 70-200mm. Definitely one of the best pieces of glass out there.