Re: Exact fl of lenses... 220 VR

[Bill Glickman <bglick@xxxxxxxx>]

Andrew

> OK, what you are talking about is NOT a change in the focal length of the
lens
> but a way to "trick" the camera into pulling more or less film through it
per
> 360 shot (or fraction thereof). Sort of like using a "EI" with film
instead of
> Film Speed.

BINGO! :-)   We are on the same page.  perfect example with film...


> So, the result of all this is that the camera does not pull the same
amount of
> film through it regardless of the exposure time you choose. Unfortunately
this
> is not a fault of the lens but the film transport mechanism or its
control. The
> reason for this is that it SHOULD be the same regardless of exposure time
but
> it seems that for your camera at least there is an unwelcome change.

   Yes, in a perfect world this would not occur, however considering the
intricacy of these small motors and gears and the volume of production, it
does not shock me... although I wish I did not have  to deal with it  :-(


> I am not sure of this but if the slit size remains constant and the camera
> changes exposure time by changing the rotation rate then I could
understand a
> change (not expect it but at least understand it). OTOH if the expusure
time is
> adjusted by changing slit size but not rotation rate then I don't see
where the
> error would creep in.

   Yep, I never tested this, but I am would bet you are right...

> Seitz would be the most appropriate or logical people to answer this
question
> (as to why the camera draws different amounts of film through it per
revolution
> / exposure time change).

      I tried asking this one to the Seitz's...I don;t think they wanted to
answer it?

Bill G


>
> Anyway, good luck ... I'm outa here!
>
> andy
>
> Andrew  o o  0 0 o . o  Davidhazy, Imaging and Photo Tech
>          \/\/\/\/\/\/          http://www.rit.edu/~andpph
> __________|        |_____________________________________
>