On Fri, Dec 01, 2000 at 01:08:19PM -0700, biesele@xxxxxxxxxxxx wrote:
Hmm, I`d suggest: make some test fotos and find out yourself.
I can`t comment the quoted literature. I think the question is
the impact of floating element design lenses when used with
extension tubes, bellows,...
In a German book from 1989, Wilfried Mordmüller printed tow pictures which
demonstrates the efficenncy of F.E.-design. And it is a very remakable
difference.
The second picture is unusable, the first is pretty sharp.
But he used the 50mm F/2 macro wide open at 1:2-magnification ratio. First
shoot
normal with lens barrel at close focus which activate the F.E-correction
mechanism.
Second with lens barrel set to infinity and the 25mm extension tube.
But I think the 50mm F/3.5 Macro is not that sensitive, especially when you
stop down,
what you usually do within macro work. So it depends on your own criterias .
My tests with a 85mm F/2 and auto macro bellows don,t show too much impact of
the
focusing barrel, in the way I use this lens for macro work. But I haven`t
evaluated them
too much, just to make sure I´m not doing a maijor mistake.
Frieder Faig
> > >Firstly, in a book I have which was written by
> Pangerl (it's a 1982 Dutch
> > >translation of a book based on The world of OM
> systems, and on a book about
> > >the OM-10), in the section about copying slides it
> is deliberately mentioned
> > >that "the lens" (Pangerl discusses the usage of the
> 80/4, the 50/3.5 and
> > >normal 50mm lenses) should be set to infinity. In
> fact, he even added an
> > >exclamation mark to that statement, which indicates
> to me that this is
> > >probably not a misprint, but a well considered
> remark. Now, from what I've
> > >gathered, the 50/3.5's close up aberration control
> group only kicks in when
> > >the lens is set to the closest focus. IOW, when the
> lens is set to infinity,
> > >as should be done according to Pangerl, this group
> will not kick in. Now the
> > >question is: which setting should I really set the
> 50/3.5 at for best
> > >results?
>
> Many of the Olympus fact sheets for the bellows and
> extension tubes specify lens focus at infinity.
>
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