I’m a day into this experiment (using the Leica 16-18-21 mm Tri-Elmar on the Sony NEX-5), and I have good news and bad news.
First, the good news:
The lens is really sharp. That’s no surprise. What is a surprise is how little sharpness is lost because of the Sony’s antialiasing filter.
The NEX-5 manual focus assist feature is just great, if your hand is steady or you can find something solid to rest the camera on. The way it works is really convenient: in normal shooting mode the bottom button on the back of the camera activates the manual focus assist feature – press it once and it magnifies the live view image in the LCD display by seven times; press it again and it doubles that magnification. The image you use for focusing is kind of harsh, but it’s perfectly adequate. What makes it so wonderful is not that it has more magnification than other cameras, or that it has a better image. What makes it so good is that the magnified focus assist is so conveniently accessed.
The big (by point-and-shoot standards), heavy (by small format wide-angle standards) lens on the tiny light, body adds up to a convenient, highly portable system. You could even call it pocketable, if you have baggy pockets. It’s definitely a portability win over putting the Tri-Elmar on an M9.
It’s nice not to have to worry about moiré-looking aliasing rainbow patterns.
Now, the bad news:
The NEX-body-to-Leica-M-lens adapter I’m using, from RainbowImaging, is too short, meaning that it puts the mounting flange of the Tri-Elmar too close to the Sony imaging plane. When the lens is focused on infinity using live view, the focus indicator on the lens itself is halfway between eight and 15 feet. Coincidentally, when focused that way, the infinity marker on the lens lines up with the edge of the right hand 21 mm f/4 depth-of-field indicator.
The fact that this flange distance problem matters so much shows just how optimistic the Leica depth of field indicators are. Sure, they’re set up for 35mm full frame, and for a camera with a 1.5 X multiplier, you should probably use the next wider stop. If I do that, and set that focal length to 16 mm and the f-stop to 5.6, I should be able to focus to indicated infinity and get an acceptably sharp image. It’s not even close to sharp.
Rather than conducting the rest of my testing using one of the depth of field markers to focus by, I’m going to order another lens adapter, and hope that I get one that’s more accurate than the RainbowImaging adapter.