Failure to acquire AF and occasional inaccurate AF in moderate to moderate-low light with the RF 100-400mm are two things I’ve probably griped about more than once on these pages. Now, after missing a number of opportunities in bright light during the past ten days or so, I see that light has nothing to do with it.
Obviously the lens can’t track quickly enough for my faster-moving critter friends, but it often confirms focus when it’s noticeably OOF. No critters completely lost as a result of its misbehavior so far, but I end up taking about 50% more shots than I normally would just to ensure ones that are focused. No apparent rhyme or reason either—some shots are obviously OOF while others are almost but not quite focused well.
Shutter speed is not an issue, and with plenty of light and contrast on various subjects it’s missed on, native contrast (or lack thereof) shouldn’t be an issue. Suffice it to say, though, that the RF 100-500mm in spite of its extra weight and bulk will be along for the ride next trip.
OTOH, the M10, a last-minute addition to the arsenal, has helped me capitalize on some unexpected landscape opportunities. Slow and plodding, yes, but worth slowing down for . . .
