**Archived posting to the
Leica Users Group, 1998/12/01**

Date: Tue, 01 Dec 1998 18:22:52 +0100

Hi Peter, According to the depth-of-field tables in Eastland's Leica M Compendium, at a distance of 2 meters the depth of field of the 75mm Summilux extends from 1.97m to 2.03m, that is 6 cm. At 1 meter, the DOF is 1.3cm (from 0.993m to 1.006m). Some time back, Erwin Puts published a table of maximum apertures at which the M cameras with the 0.72 rangefinder could be focused. The numbers for the most common focal lengths are: 21mm: f0.15 28mm: f0.26 35mm: f0.41 50mm: f0.84 (so the Noctilux comes close to the limit) 75mm: f1.88 (so the Summilux slightly exceeds the limit) 90mm: f2.71 (so the Elmarit comes close to the limit, while the Summicron exceeds it) 135mm: f6.1 (so all current 135mm lenses exceed the limit) Morale: focus carefully with the longer lenses! Nathan Peter Niessen wrote: > Dear all, > > in his famous article ,,J'accuse Leica'' Mr. Ross proposes the > following experiment: > > Place a Leica M 2m apart from an object, focus, move 6mm away and > check if you can see a difference. He states that the depth of field > for the 75mm Summilux is 6mm at 2m distance. Is that really true and > not a typi? Common Literature tells that d.o.f. is 6cm. > > However, I wonder about two things: > 1. Can you see a difference with an SLR there? > 2. Are there other errors on the range finder? Is there a formula > which tells you delta_d = delta_d (distance, aperture, rf_base, ...)? > > Cheers, Peter. > > Peter Nießen > e-mail niessen@ifh.de - -- Nathan Wajsman Overijse, Belgium Photography page: http://members.tripod.com/~belgiangator/index.html Motorcycle page: http://www.geocities.com/motorcity/downs/1704/index.html