A few quick tips, and yes, focusing is the real test on a rangefinder camera. I can't add much to the vision issue which earlier responses answered. I use a 1.25 magnifier with every lens and I think it is almost required for any lens faster than 2.0 to help get a super sharp focus.
If you are trying to learn to use a Leica for the first time, make things easier to begin with and practice on learning to focus.
1. Set the speed to "A" so you don't have to worry too much about exposure. You can go to manual settings later.
2. Try and get to f 5.6 or f8 if possible in your ISO settings so you can work on successful focusing techniques. You can work with narrow dof settings later. (To insure a margin of error in focus, use a larger f stop
3. The manual has recommendations on how to hold the camera for critical balance and focusing without blocking light or part of the image. That's a good place to start, you may develop better techniques that work for you.
4. Shoot, shoot, shoot - delete, delete, delete: Shoot a hundred images a day - it doesn't cost anything except a bit of time. Take the camera to work, for daily walks, shoot with it at stoplights, carpools, in your home, at the mall, EVERYWHERE. And rack the lens out of focus after each shot to really hone your focusing technique. Then load the images into your processor and see how consistant your focusing is. Delete all of them and start again tomorrow (unless you get some keepers of course).
5. You will always miss focus on some photos, the same holds for DSLRs with auto focusing. Where the rangefinder can be extra hard to focus is in certain situations where a) The light is flat and the patch looses contrast b) there are multiple small images in the patch at close focusing distance of some lenses(small flowers come to mind with a 90mm) c) dark conditions of course. d) Some things are just hard to focus because of the light and color of the object e) You will learn to recognize these types of things and take more time to focus.
6. My fingers are not very long and I use a soft release on my camera to help make that instant exposure when my focus patch aligns.
Focus and composition are the strong points of a rangefinder system but it does take practice to get good (perhaps "natural" would be a better term), but a lot of it is muscle memory. I like the idea of racking the focus to infinity each time. In time you will get good enough to focus the lens and press the shutter at the instant the rangefinder snaps into focus.
Now, if Leica would double the size of the rangefinder patch, or make a moveable patch that reads eye pupil (retina?) movement so the patch was always over the area you want to be razor sharp, that would be a great improvement for the next generation body.
O.C.
