In article , -hh
says...
Specifically, when Autofocus capability is disabled when a certain
f/stop value is exceeded.

Why?

If memory serves, the common "upper limit"
value had been f/5.6, with some exceptions at f/8 (such as offered
only on higher end bodies, and/or only at the center focus point).

I have the Olympus 75-300 which is F6.7 at the tele end, but autofocus
works also at the tele end.
--
Alfred Molon

Olympus E-series DSLRs and micro 4/3 forum at
https://tech.groups.yahoo.com/group/MyOlympus/
https://myolympus.org/ photo sharing site