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
Doug wrote:
> On Thursday, February 26, 2009 10:51, Dawid Loubser wrote:
>> Hi All,
>>
>> Can somebody explain this to me: I have two versions of the OM Zuiko
>> 50/1.4 -
>>
>>
>> Since I don't have a proper loupe, I have a habit of using a fast 50
>> for a loupe (makes a pretty
>> good one). For some reason, the OLD silvernose 50/1.4 makes a
>> brilliant, crisp loupe which is
>> a pleasure to use, whereas the new (optically better) 50/1.4
>> absolutely sucks: It appears to render
>> an image of completely the wrong dioptre, it's like putting on the
>> wrong glasses: Everything is blurred
>> and it strains the eyes.
>>
> Are they both set to the same focus? What I mean is one set to infinity focus
> and one set to its closest focus. I not sure how the 50/1.4 focuses. I sold
> mine several years ago because it was too soft compared to a 50/1.8.
--
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