>From: Moose <olymoose@xxxxxxxxxxxxx>
>
>Jan, you are saying Repro ratio when you are talking about FOV.
No, I meant reproduction ratio -- I just wasn't very clear with the rest of
it... :-(
>don't you have your example backwards?
Yes. Sorry. "If a flower covers a 35mm frame at six inches with a 100mm lens,
that same flower will cover a 4/3 sensor at six inches with a 50mm lens."
Ralph further clarifies:
>The
>50/3.5 macro does 1:2 at 23 cm (if I remember corretly), it means that an
>object at that distance will be reproduced at half the size on the focal
>plane - no matter what size is the sensor/film!
but then gets confused here:
>I suspect the 50mm macro for the 4/3 system will work the same as "our" 50
>macro, so working distance in the field can be difficult.
Not quite the same. Let's work backwards. Say you want a flower to fill the
frame. In 35mm, it has to fill a larger area -- a smaller reproduction ratio is
required. In 4/3, it needs to fill a smaller area, requiring a larger
reproduction ratio. Thus the working distance is proportional to the field of
view, NOT the reproduction ratio, and will be identical on a 50mm 4/3 lens as
on a 100mm 35mm lens.
This becomes quite clear if you've done any large format work. The 150mm
"normal" lens for 4x5 work produces the same image size, relative to the film,
at the same working distance as a 50mm lens does for 35mm work. (If course, the
reproduction ratio is smaller, though.)
I do a lot of macro in various formats, and feel quite confident of this, but I
guess I'm having some trouble explaining it.
Did that help, or did I confuse things even more?
--
: Jan Steinman -- nature Transography(TM): <http://www.Bytesmiths.com>
: Bytesmiths -- artists' services: <http://www.Bytesmiths.com/Services>
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