Archived posting to the Leica Users Group, 2002/04/16

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Subject: [Leica] Re: need suggestion on leica lens 180mm f(ilter size not E55)
From: "telyt@earthlink.net" <telyt@earthlink.net>
Date: Tue, 16 Apr 2002 18:42:34 -0400

> what is the lifesize can it be with macro adapter?  oh also, micro adapter 
> mean ELPRO ?
 
Olivier, ELPRO and macro-adapter are not the same.  An ELPRO is a 2-element lens that screws into the filter threads of the main lens.  There are no ELPROS big enough to screw into the filter threads of a 180mm Elmarit-R.  Perhaps other camera makers sell larger 2-element close-up lenses but I'm not familiar with those other brands.
 
The Macro-Adapter-R is a 30mm extension tube that fits between the main lens and the camera body.  With a 180mm lens you need a lot of extension to get much magnification.  For 1:1 reproduction ratio, a 180mm lens needs 180mm of total extension (extension tubes + the extension of the lens' focussing helix).  For 1:2 reproduction ratio, i.e., half life size, the total extension needs to be 180mm/2, or 90mm.  The Macro-Adapter-R is 30mm so without using the lens' focusing helix you'd get a 1:6 reproduction ratio, since 180mm/6 = 30mm.
 
These calculations work with lenses that focus by moving the lens as a complete unit.  Internal-focus lenses OTOH focus by changing the focal length of the lens so with these lenses the calculations are valid only with the lens focussed at infinity.  Neither of the non-APO 180mm Elmarit-R lenses is internal focus.
 
Doug Herr
Birdman of Sacramento
http://www.wildlightphoto.com
 

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Replies: Reply from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] Re: need suggestion on leica lens 180mm f(ilter size not E55))