I agree, the focus setting of the 50/1.4 makes no difference, as the
entire assembly moves forward/backwards.
I have always been using the lens the other way around, i.e. front
element pointing to the photograph. I always put it down (i.e. resting
against)
the negative sleeve. Hmm... The late 50/1.4 is more deeply
recessed (i.e. has a deeper filter ring) than the ancient 50/1.4 - and
I think
by some strange co-incidence the old one had the perfect distance, and
I obviously
could never get the new 50/1.4 close enough for that same viewing
experience.
Chuck, would your method not produce much less apparent magnification?
(Don't have the
stuff here at work to try, but will do so later at home). From my
understanding of the
optics involved between the human eye and the lens, would your method
not work better
if one also positioned a large piece of ground glass in front of the
lens? (i.e. the same
as what effectively happens with a reversed 50 on a bellows, although
only a tiny portion of
the available image is being projected onto the camera's small piece
of ground glass.
I just don't see how a 50mm lens as loupe could produce an apparently
big image, unless
one jams one's eyes close up to the lens. And if one's eyes are close
to the lens, one surely
does not want parallel rays coming out of the lens? (for only a small
portion of those rays
will enter the retina).
Anyway, please feel free to correct me :-) I have tried to experiment
by hand-holding the
lens as you suggest, but perhaps (now that I think about it) it will
only work if the lens is
precisely raised by 46mm? i.e. even a 5mm difference will produce a
significantly different image?
On 26 Feb 2009, at 7:59 PM, Chuck Norcutt wrote:
> The 50/1.4 does not have any internal focusing elements. Focus is
> achieved by moving the entire optical assembly forward and back.
>
> When used as a loupe the object being viewed should be seen from the
> lens's point of view... as though the object was film and the lens is
> focused on infinity. The lens should be focused on infinity and the
> lens mounting flange positioned at 46mm (Olympus OM register distance)
> from the object being viewed. When so positioned the lens produces
> parallel rays which will make the object appear (to your eye) to be at
> infinity. If you wear glasses for viewing at infinity you should
> wear them.
>
> Of course, you may position the lens and eye at other distances which
> will make the object appear to be at other than infinity. If you need
> glasses the correction needed will be other than at infinity. The
> back
> of the lens should be toward the object being viewed for the same
> reason
> that we reverse normal lenses when doing close macro work. The design
> of the lens is better optimized for that orientation and distance.
>
> Chuck Norcutt
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