From: jpglori@srv.PacBell.COM (John P. Gloria)
Subject: Re: AF speeds
Organization: Pacific * Bell
Distribution: usa
Date: Fri, 4 Sep 1992 15:12:39 GMT

In article <22331@venera.isi.edu> finn@dalek.isi.edu (Greg Finn) writes:
>In article <1992Sep3.043649.16482@PacBell.COM> jpglori@srv.PacBell.COM (John P. Gloria) writes:
>
>	No problem.
>
>> ...  I am curious though on your method(s) used
>>in your controlled setting.  What measurement tool/guide
>>did you employ to determine focusing speed?
>
>	I used a white board in a large conference room.  Using a
>tripod I set up at a couple of focal length multiples away from the
>board, 10 and 20 if I remember correctly, and farther for short focal
>lengths.  Load fresh battery sets.  I verified that neither the F4 nor
>the 8000i could AF on it.  This is no surprise ... flat white and no
>contrast.  Body AF illuminator was disabled, no flash, and so on.
>
>	Measuring and mounting the cameras on tripods I outlined the
>sensitive AF regions on the white boards in black.  Lenses set wide
>open, which were approximately equal for the lenses that I tested.
>Same focal lengths of course, small, middle, large for zooms.  I then
>placed in the middle of the zones a small box 1/2 the narrow dimension
>of the focus zone on the white board.
>
>	Set the focus to the closest equal non-macro focusing distance
>and infinity.  Punch the shutter release for AF and listen.  So after
>all that careful set-up I didn't accurately measure the focus times.
>I determined that the difference appeared too small for me to notice.
>Your mileage may vary.  The lenses I tested were the middle consumer
>quality zooms: 35-70, 28-85, 70-300, 75-300, or whatever was as close
>as possible with the Minolta and Nikon AF lines at the time (June
>1990).
>
>	Since then, Nikon has redesigned its line, certainly the
>28-85, possibly the 75-300, but I think that was already an "N"
>version.  The F4 has remained the same but the 8000i is no longer the
>top of the line Minolta.  Their newer bodies may be faster.
>
>--
>Gregory Finn	(310) 822-1511
>Information Sciences Institute, Marina Del Rey, CA 90292

To: finn@dalek.isi.edu
Subject: Re: AF speeds
Newsgroups: rec.photo
Organization: Pacific * Bell
Cc: 
Bcc: 

In article <22331@venera.isi.edu> you write:
>In article <1992Sep3.043649.16482@PacBell.COM> jpglori@srv.PacBell.COM (John P. Gloria) writes:
>
>	No problem.
>
>> ...  I am curious though on your method(s) used
>>in your controlled setting.  What measurement tool/guide
>>did you employ to determine focusing speed?
>
>	I used a white board in a large conference room.  Using a
>tripod I set up at a couple of focal length multiples away from the
>board, 10 and 20 if I remember correctly, and farther for short focal
>lengths.  Load fresh battery sets.  I verified that neither the F4 nor
>the 8000i could AF on it.  This is no surprise ... flat white and no
>contrast.  Body AF illuminator was disabled, no flash, and so on.
>
>	Measuring and mounting the cameras on tripods I outlined the
>sensitive AF regions on the white boards in black.  Lenses set wide
>open, which were approximately equal for the lenses that I tested.
>Same focal lengths of course, small, middle, large for zooms.  I then
>placed in the middle of the zones a small box 1/2 the narrow dimension
>of the focus zone on the white board.
>
>	Set the focus to the closest equal non-macro focusing distance
>and infinity.  Punch the shutter release for AF and listen.  So after
>all that careful set-up I didn't accurately measure the focus times.
>I determined that the difference appeared too small for me to notice.
>Your mileage may vary.  The lenses I tested were the middle consumer
>quality zooms: 35-70, 28-85, 70-300, 75-300, or whatever was as close
>as possible with the Minolta and Nikon AF lines at the time (June
>1990).
>
>	Since then, Nikon has redesigned its line, certainly the
>28-85, possibly the 75-300, but I think that was already an "N"
>version.  The F4 has remained the same but the 8000i is no longer the
>top of the line Minolta.  Their newer bodies may be faster.
>
>--
>Gregory Finn	(310) 822-1511
>Information Sciences Institute, Marina Del Rey, CA 90292

Gregory,

No offense intended here.  I appreciate your ingenuity in preparing
a testing environment for the various lenses. However, there is
no conclusive evidence in your original post in which you stated
the Nikon AF (F4) lenses are faster focusing than the Canon AF
lenses.  You only tested Nikon cameras/lenses. Relying on your
listening ability to detect any difference in focusing speed
between two Nikon cameras is not same as comparing a Canon AF
and a Nikon F4.  I would bet that your same test would result
in you actually noticing a quicker focusing response/action from
the Canon AF cameras (any of their AF cameras) with a USM lens
mounted.  Again, you are heading in the right direction. Please
do take my reply as a flame. Have a GREAT weekend!
-- 
        ---------  John Gloria - jpglori@pacbell.com	--------	
 		"You cannot depend on your eyes when your imagination
	       is out of focus."   -     Mark Twain
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