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RE: [OM] iS-10(0) / iS-20(0) / Centurion AF Question

Subject: RE: [OM] iS-10(0) / iS-20(0) / Centurion AF Question
From: Hans van Veluwen <HVeluwen@xxxxxxxxxxx>
Date: Tue, 10 Oct 2000 10:33:01 +0200
:Hans, doesn't the term "predictive AF" imply that the AF 
:system of the camera
:actually is able to "predict" the approximate distance to the 
:moving subject in
:advance? Remember what they said in the iS-30 Pop Photo test, where the
:photographer "was able to keep continuous focus on the sports 
:car UP TO THE MOMENT
:he began a panned exposure". Correct me if I'm wrong, but I 
:presume [simple]
:Continuous AF (w/o the predictive feature) just keeps the 
:focus position of the first shot? 

What I understand from it, is that non-predictive continuous AF (like the
iS-3000 has) at a certain interval will check the focus as long as the
shutter release is (halfway) pressed, and when the subject is out of focus
it will try to adjust, trying both directions using the previous focal
setting as a starting point.

Predictive AF should remember some previous correct settings, and thus
detect when a subject is moving towards or from the camera at a more or less
constant speed, allowing to predict when the subject will be out of focus
and what presumably the next correct focal setting will be. This should
allow the system to adjust faster.

And yes, without continuous drive predictive AF is only useful when you want
to follow such a moving subject and make one shot of it at the right moment.
Series can only be made at an interval of 1 sec. or something like that,
making the system less usable.

:I'm 99,9 ure that the 'predictive' part of the 
:AF system in iS-30(0) really is a completely new feature of that camera.

You're probably right; it would really be stupid to implement such an
interesting feature and then don't mention it.

:At least my iS-200 manual doesn't mention continuous AF, but I 
:suppose that doesn't say much.

No it doesn't since the Centurion's manual doesn't mention it either. Well
fortunately the iS-200 is still available so I can try one in a shop.
Apparently there are no list members who owns an iS-100 or iS-200.

hnz


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