Does AF work with small aperture lenses (Sigma 150-500)

Started Jan 25, 2012 | Discussions thread
Chris J Newman
Forum MemberPosts: 72Gear list
Like?
Re: Yes, but with constraints & limitations
In reply to stuntmonkey, Jan 26, 2012

stuntmonkey wrote:

The minimum aperture specified is not a brightness requirement, it's a geometry requirement, as it is a function of the distance between the measuring points on the AF array.

That’s what I expected, and I was concerned that the phase detection system would need an aperture of at least F5.6 to make its comparison. I remember one or the other half of the split screen in my Pentax manual focus viewfinder being blacked out with a 2X teleconverter on my F4 telephoto zoom. I’m delighted to have confirmation that my D90 should autofocus OK with the Sigma lens.

 Chris J Newman's gear list:Chris J Newman's gear list
Nikon D800
Reply   Reply with quote   Complain
Post (hide subjects)Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow