I don't recall having seen any RF patch size comparisons or measurements anywhere. You're also unlikely to find someone with broad enough familiarity on that subject who has made a careful comparison among all the options you might want to consider. There is an RF baseline comparison at http://www.cameraquest.com/leica.htm with some comments, but not about RF patch size. He also doesn't include ZI info. I think that may be because he had the brand initially, but it was pulled from him early on to service bigger dealers with more influence.
It's been years since I used an M3, so I don't have any worthwhile basis for comparison of RF patch size comparisons.
I have the R3A (same basic finder as R3M) and like it a lot, but it won't do the 28mm you're considering without an accessory finder. You can use a Nikon DG-2 2x finder magnifier on the R3A, and Nikon diopter lenses for the FM and FE cameras fit the R3A. The Nikon DG-2 doesn't even see the 90mm frames though. It only sees what would be the larger central circle on the Nikon SLR finders, but it flips up for full finder viewing. That exposes a bare metal rim, so watch that if you're a glasses wearer.
There is also a smaller 1.3x magnifier from Japan Exposures (formerly megaperls) that fits the C/V R3A/M http://www.japanexposures.com/shop/p...c9b56d0e18eff2 You have to order it for your Nikon SLR because it violates a US Leica patent for rangefinder magnifier use. I don't know how much of the R3A finder it shows.
Last edited by Lee L; 01-22-2009 at 02:38 PM. Click to view previous post history.