Since I am a birdwatcher at heart, a tele lens has always been an obvious thing to find in my camera bag. For quite a few years now it has been the Tokina AT-X 400/5.6. That is a lens that many people have good things to say about, but I was never completely happy about it. The auto focus is slow and noisy, and it doesn't deliver the sharpness I want. Perhaps I ask for too much from the lens (it was not very expensive), but I have felt that it needs upgrading.
And now the time is here. I am not going for the large cannons (such as 300/2.8 or 500/4), price being one issue, but also the bulk. That doesn't exactly make the decision easier. If you want one of the big ones, there is usually just one (or maybe two, the newer version with IS and the older one without) to choose from. But in the lower price range, the world looks quite different.
The lenses I choose between are mainly two: the Canon EF 100-400mm f/4.5-5.6L IS USM and the EF 300mm f/4L IS USM (paired with the Canon 1.4x tele converter). Zoom vs. prime. Since I am not religious in that question (I have both zooms and primes and I like both worlds), that parameter is not a deciding one.
When I first concretely started to think about a tele lens, the 300/4 was the obvious choice. I already have a 70-200/2.8 (the Sigma EX one) so I already have that range covered. I am looking for something above 200 mm. The 300, together with the 1.4x TC would provide 300 and 400 mm. But then the thought came that the 100-400 might in some situations replace the 70-200. I would not let it replace it altogether (the 70-200 is after all a 2.8 lens), but say I want to make a trip with minimum packing. In such a scenario the 70-200 could stay at home. That is 1.2 kg less to carry. I usually don't consider weight as an issue, I carry a lot with me in the field, but sometimes you want to go lightweight. The 300 prime would not allow that.
But then I thought, "What the hell, I am going to use that zoom in the long end during most of the time anyway, get the prime, it's the one I thought of first and it's sharper". And I was happy. I made a decision!
But then I have a friend with the 100-400 zoom in his bag, and we were out shooting a day, and I borrowed his lens, just to try it out. That is one fine lens. Maybe I wasn't so sure after all... The zoom IS more versatile. And it is quite sharp indeed. Not as sharp as the 300/4 + TC (at least I don't think so), but sharp enough. And optical sharpness is not all. When in the field, conditions are usually less than optimal. There is a lack of light, you may not have your tripod head tightly locked because the subject you are shooting is moving around and so on. In these cases, perhaps the more efficient IS will provide sharper pictures with the zoom, than the prime would do in the same situation.
Right now, I am exactly in the middle between those two lenses, and my mind changes
I guess I will try to borrow the lenses, get out in the field for a few hours and try them, side by side in natural conditions and see how they perform with me behind the wheel. Perhaps that could help decide.
If you happen to live in the Malmö area of Sweden, and you own the 300/4 L IS, and could think of lending it to me for a day or so, please let me know :o)
(Any input in the matter would be valuable, don't hesitate to comment…)
Update (March 2, 2005): I finally decided for the EF 300mm f/4L IS USM combined with the Canon 1.4x extender. I have not had that much time with them in the field, but so far I am totally happy with that decision.