Archived posting to the Leica Users Group, 2002/12/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]on 12/1/02 7:39 AM, Henry Ting at henryting10@yahoo.com wrote: > > Can someone give me a lecture on the ELPRO dedicated > to the 100mm f2.8 APO macro ? > > I would imagine getting to a 1:1 ratio, a regular > extender will give me better performance compared with > the ELPRO with the additional optics. What do I gain > with the ELPRO ? > The 100 APO's focussing mechanism is somewhere between front-group focussing and internal focus. The lens is optimized for each focussing distance by shifting some elements relative to others as the focussing ring is turned. Extension rings can be used but since they change the distance from the rear element to the film plane, all the fancy optimizing mechanism would be for naught. The ELPRO allows closer focus without losing the advantages of the optimizing tricks, so in this case, the 100 with the ELPRO designed specifically for the 100 APO will out-perform the lens alone with extension tubes. Doug Herr Birdman of Sacramento http://www.wildlightphoto.com - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html