Last week I took delivery of a gently used 100-400 from KEH for use primarily as a birding lens, as my 55-200 doesn't quite have the reach I want. I am shooting an X-H1 body.
Beyond the learning curve of using such a large and heavy lens, I'm pretty pleased with the image quality and sharpness; any blurriness has been operator error.
However, I'm concerned about its AF performance. Sometimes it focuses quickly and accurately, and sometimes it just fails to focus at all. Specifically, when I half-press the shutter (or the AF-ON button if I'm in manual focus mode), nothing happens.
Let's say I'm focusing on a bird feeder that's 20 feet away and it decides not to focus. Sometimes focusing on something further away or closer "wakes it up" and then it will focus on the feeder; other times, it simply refuses to focus at all. No hunting, no searching, just... nothing.
I primarily shoot in single-point AF, but I have experimented with C-AF and wide tracking as well, but that doesn't seem to make any difference. I have experimented with the focus limiter, thinking that I was focusing on something too close with it turned on, but that doesn't seem to be the issue either.
Is this typical of this lens, or is there perhaps something wrong with this one? I'm trying to figure it out before my return period expires.
I don't have the same issues with my other lenses, including the 55-200. Or is this a shortcoming of the X-H1 perhaps?
Both the camera and lens are running the latest firmware.
Thanks in advance for any guidance.
Jim
