Icoz, Evrim wrote:
How do they measure AF Speed? I sit objective or subjective? I always
wondered about hat.
thanks.
-----------------------------------------------------------------------
They actually just comment on it. I do not believe they measure it as it
would vary from Camera to camera.
For example, unless you compared lenses on the same body (say an EOS-3) it
would vary widely.
I wrote to Herb Keppler and suggested Pop Photo consider comparing AF speeds
for various lenses and include them in the review. My suggestion was to
compare a Canon lens, then a Sigma, Tamron etc. on a Canon body and do the
same for Niikon, Minolta, etc. He responded with a nice letter, albeit
terse, and said readers would not be interested in this.
Apparently, readers in Europe are, so for anyone interested, below is a
report from ColorFoto done back in '97(?).
ColorFoto measured AF speed, AF accuracy and AE accuracy. The rating
was based on all three tests. Since the AF accuracy was within the DOF
for all tested cameras, the final rating is useless.
The interesting part was AF speed. They tested with a 50/1.4 lens.
The results in seconds at EV 15, 10, 5 and 0:
Nikon F5: 0.19, 0.19, 0.29, 0.41
Canon EOS-1n: 0.23, 0.23, 0.33, 0.51 (w or w/o booster)
Nikon F90X: 0.26, 0.26, 0.35, 0.53
Pentax Z-1p: 0.27, 0.29, 0.39, 0.58
Pentax MZ-5: 0.28, 0.31, 0.40, 0.61
Minolta 700si: 0.27, 0.32, 0.40, 0.60
Nikon F70: 0.30, 0.30, 0.39, 0.78
Canon EOS-5: 0.30, 0.34, 0.42, 0.60
Canon EOS-50: 0.33, 0.37, 0.43, 0.63
Minolta 500si: 0.40, 0.40, 0.45, 0.67
Contax AX: 0.39, 0.42, 0.50, 0.60 (back focus in body with MF lens)
Canon EOS-500N: 0.45, 0.52, 0.49, 0.73
Minolta 300si: 0.47, 0.50, 0.53, 0.72
Nikon F50: 0.49, 0.50, 0.52, 0.75
Pentax MZ-50: 0.49, 0.49, 0.56, 0.79
Sigma SA-5: 0.56, 0.57, 0.61, 0.80
AE accuracy was within 1/3 stop for almost all cameras. Some low-end
cameras was biased towards overexposure that is best for print film.
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
