How sharp is the leica apo telyt m 135mm f 3 4?

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From Leica APO-Telyt-M 135mm f/3.4: Leica APO-Telyt-M 135mm f/3.4: A prime lens by Leica for Full frame cameras, 135mm f/3.4. The longest current M lens; precise focusing is easier with live view or an EVF. Specs - Maker: Leica - Focal length: 135mm (prime) - Maximum aperture: f/3.4 - Made for: Full frame sensors - Mounts: Leica M - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Leica M): as marked, 135mm. ...

From Portraits: Aperture and background blur: A wide aperture (a small f-number like f/1.8) gives a shallow depth of field: sharp eyes, soft background. Blur also grows with focal length, with getting closer to your subject, and with putting more distance between the subject and the background. Moving your subject away from a wall often does more than a faster lens. At f/1.4 and wider, the depth of field can be thinner than a face. Stop ...

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