Archived posting to the Leica Users Group, 2001/05/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> >Mark, >I think you have the 24M ? >It is INCREDIBLE at f4, 5.6, 8. >At higher apertures I seem to get great overall sharpness but NOT the >same kind of incredible sharpness that occurs at the mid-apertures. Not >that its bad when stopped down, its just noticably better from f4-f8. > >Henry If you have a couple of frames left over on a film, do shot a series of newpaper pages starting with the lens fully open and make a shot for every stop. Make sure that the page is flat and that you shoot at an angle of 90° from the page, both vertically and horizontally (i.e. your camera at the same heigth as the center of the page etc). Make sure the light is even and expose as indicated by a grey card, but if you have none close down 1 or two stops from the reading the page gives you with an M6 meter (two stops if no dark pictures on the page). If you test wide angle lenses, you want to make sure there are some large size headlines on the page. Keep the page just in case you want to test another lens later, it makes comparisons so much easier. I do my tests with Delta 100 developed in Xtol 1+1 and I do 16x enlargements on 9.5 x 12 inch paper making sure that one corner of the negative and the centre is on the print. (You don't need four corners, and certainly not the centre only). OK, for some types of photography corners are not that important (portraits!) VERY IMPORTANT: When enlarging, put the negative so that the part you want to enlarge is in the middle of the negative holder because otherwise the print quality may be degraded by your enlarger lens. Very interesting results, beats MTF (or whatever they are called) curves. That test was the final nail in my 15mm Heliar's coffin. Confirmed what I had been suspecting Chris - -- Christer Almqvist D-20255 Hamburg, Germany and/or F-50590 Regnéville-sur-Mer, France