I just realized that with Canon EF400/5.6 + Canon 37 mm extension tubes I had never problem with AF. Here efective aperture must be min. f/8, so the thing about the angle of the rays seems to be logical.
Fero -----Original Message----- From: Bob Talbot Sent: October 30, 2002 1:43 AM To: eos Subject: Re: EOS EES D60 and f/8 > The AF sensors depend on angular information, interpreted as contrast > by the circuitry. When the rear exit pupil of a lens is too small (ie, > the side to side angle of the rays hitting the sensors is too narrow), > they don't respond correctly anymore. If they could respond correctly, > AF would be possible. If they don't respond correctly, why > would you want a readout??? Henning Have you actually tried this or is this repeating stuff from the brochure. Not for the D60 I admit, but on other cameras in the EOS range the lenses will autofocus satisfactorily with "slower that f5.6" third part lenses, or with tubes/teleconverters, when the pukka Canon lenses will not. Well, satisfactory in the sense of being in focus, yes. Less reliable with featureless subjects, yes too. I suspect Canon are protecting us from ourselves ... they can't guarantee the AF so they don't let you try. With most things in design, it's not really a cut-off between works or does not but a progressive fall off in performance.... Q * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
