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[OM] Re: Anyone Have an ED12-60/2.8-4?

Subject: [OM] Re: Anyone Have an ED12-60/2.8-4?
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Fri, 11 Jan 2008 21:02:43 -0500
I have no specific knowledge of how the Oly autofocus works but can 
speculate on purely mechanical grounds that the operation is a dance 
between camera and lens.  The camera is determining focus or near focus 
at a point when the lens' focusing motor is still running.  The lens can 
start, stop, accelerate or decelerate or reverse the motion.  If it's a 
fast running process there may be coasting time involved between the 
time the command is issued to stop and the actual stoppage.  I suspect 
all of these behaviors can be fine tuned by changing parameters in both 
camera and lens.

Chuck Norcutt

Dan Mitchell wrote:
>> If not, is the auto focus precision of the 12-60, or any other Olympus 
>> digital lens, a function of the mechical / electronic interaction of the 
>> lens itself in combination with the camera body upon which it is mounted? 
>> How can any software downloaded on one's computer upgrade the auto focus 
>> capability of on's camera and lens?
>>
>> For any new software to be effective would it not have to be downloaded into 
>> the camera itself?
> 
>   Depends on how the lens works. If the camera sends the lens a signal 
> saying "focus yourself at X feet", then it's entirely up to the lens how 
> it translates that signal into motion of the motors inside itself -- 
> maybe it has improved knowledge of the amount of torque required to 
> reposition its elements to focus at X away, so it can accelerate faster 
> or something?
> 
>   Theoretically you could time things so that based on how long it takes 
> the lens to stop itself down, it could start stopping down before it's 
> focussed, so that as long as the stop-down and focus happen at the same 
> instant, you reduce shutter lag. That sort of thing.
> 
>   On the other hand, if the lens is dumb and just knows "focus further" 
> -vs- "focus nearer", then it's harder to see what a firmware upgrade 
> could do.
> 
>   -- dan
> 
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