On Sat, 24 Feb 2001, Ken Lin wrote:
> The Elan 7E has only 5 ECF/AF points, this actually means it has less ECF
> points to process and therefore it has the fastest ECF performance of all
> current Canon line up, including the -3 and 1V! The Elan 7e also allows ECF
Well... you might very well be correct in that the ECF in EOS 30 (Elan 7e)
is the fastest of EOS line, but certainly not only because it has only 7
(not 5) AF points - after all the EOS 50e has only 3 and it's clearly
slower. No the main thing is the processor that is driving the ECF system.
And I'm not at all convinced that the number of AF points would have
much to do with the speed of ECF. If you think about it, there are
separate sensors for sensing the position of the eye. There are IR leds
and then sensors that give the ECF system the data it needs. Based on that
data the system then calculates the position of the eye and then just
picks the AF point that is nearest to it. So the input data is the same
regardless of the number of AF points, but only in searching for the
closest point there is a difference in how many AF points there are. So in
theory there is a difference, but as we don't know anything about the main
ECF calculations, it's quite hard to say if it's making much of a
difference (I know a little about searching for the nearest AF point, and
it can be "slow"). More difference is due the algorithms and the
processor... which both can (I don't know, just speculating) be newer in
the EOS 30 than in EOS 3 for example. (EOS-1V doesn't have ECF...)
It's another situation for the accuracy of the ECF... assuming the
underlying EF is equally accurate, then the number of points that the
system has to choose from makes a difference. Just try it with EOS 3 -
limit the AF points to 11 via the CF, and you will notice that the ECF
works much more reliable.
> to follow where you look even after you have half pressed the shutter to
> lock initial focus, this can be very good in some cases when you decide to
> re-focus on the fly to a different point within the frame, with the -3 and
> the 1V (I believe), you have to first release shutter, look at a different
> ECF and then half press again to change the ECF point.
But I consider the way it's done in EOS 3 to be better. I usually focus
first, then re-check everything in the frame... which would now according
to this result in another selection of AF point... not good. Unless you
are not talking about the "One Shot" focus, but rather continuous... there
I seldomly use ECF anyways, so I can not really say if it's good or bad...
Bye,
Hugo.
************************************************************
** Hugo Gävert **
** [EMAIL PROTECTED] http://www.hut.fi/~hugo **
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