Olympus-OM
[Top] [All Lists]

Re: RE :[OM] EXTENSION FOR 20mm MACRO

Subject: Re: RE :[OM] EXTENSION FOR 20mm MACRO
From: Mark Dapoz <md@xxxxxxxxxxxx>
Date: Thu, 10 Feb 2000 10:40:05 -0500 (EST)

On Thu, 10 Feb 2000, Frank van Lindert wrote:

> On Wed, 9 Feb 2000 19:23:59 -0500 (EST), Mark Dapoz <md@xxxxxxxxxxxx>
> wrote:
> 
> >Both the 20/2.0 and 38/2.8 can mount directly to a body.  The 38mm seems
> >to give about 1.5:1 magnification without extension and the 20mm about
> >3:1 (as a rough estimate, I didn't take any actual measurements).
> >                             -mark
> >
> Physically these short macros could be mounted to the camera body, but
> you won't be able to focus... 
> I wonder how you dit it - maybe you stopped the lens down to f16 or
> f22 and got some kind of image.

I checked again this morning, this time with a little more accurracy, and
the results are more or less the same.  Both the 20mm and 38mm when
mounted directly on the camera gave a crisp sharp image in the viewfinder.
This time I used a ruler as the subject and "measured" the image size in
the viewfinder.  In both cases I didn't stop the lens down and I had the
focus adjustment fully retracted.  The 20mm showed about 10mm of the ruler
and the 38mm about 27mm. That would work out to a reproduction ratio of
about 3.6:1 for the 20mm and 1.3:1 for the 38mm.  I used a 4Ti for the
measurements so the numbers will be off a but since the viewfinder
doesn't show 1000f the actual image.  For completeness, the working
distance of the 20mm was about 2cm and the 38mm about 5cm.

> They need either the auto 65-116mm extension tube, or the bellows (or
> any other extension of at least 50mm, if I remember well)

Looking though the viewfinder, that doesn't seem to be the case.  I've
never actually tried taking a picture with these lenses mounted directly
to the body, so perhaps the final result on film may be disappointing
compared to what's seen in the viewfinder.
                                -mark


< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz