Canon 100-400 L i vs ii

Jon Tarbuck wrote:

Am looking to purchase a telephoto lens for my 5D Mark III, and have narrowed it down from a focal range, size and weight point of view to the two Canon 100-400 L lenses.

I shoot wildlife, some birds, and quite a few of my two and half year old son in generally good lighting conditions.

The first version of this lens is going to disappear at some point, and is obviously a great deal cheaper than the new version right now - but is it false economy to buy the older version if the new one is so much better? I've heard that the autofocus performance of the newer model is a lot better, and that it's a lot sharper across the frame, at all focal lengths and pretty much all apertures...

I owned the original version from shortly after its introduction, and replaced it with Version II at the end of 2014, shortly after it was introduced. The original version seems to have been a bit hit-and-miss, certainly in its early years, although reports from users of lenses made later in its production run seem to be more positive. At its best, the original version was pretty good in the centre, rather less so into the corners, and tailed off somewhat towards 400mm. Mine suffered from optical problems that were a bit different after each of many trips to repairers, including Canon at Elstree, but were never really fixed. I have seen no reported optical problems with Version II, and mine is marvellous. In terms of build quality, the difference is like night and day. The original version was prone to failure of the ball-bearing zoom mechanism, and mine failed in that way, requiring an expensive repair. Finally, the original version was never good with Canon Extenders, but Version II works really well with the Extender 1.4× III.

In short, go for Version II – you will not regret it.