Originally posted by tokyoso If you're a good judge of distance, the 50mm may work well with focal zones, but its still pretty thin comparatively.
The thinness of DOF depends on distance from lens to subject, and f-stop, and focal length. Assuming you're shooting the same lens and f-stop, DOF gets thinner as the camera gets closer. Generations of 35/FF photographers didn't seem to have too much trouble focusing fast 50s, and because of the wider FOV on FF/35, they (we) could work closer to a subject.
Quote: The in focus indicators don't work very well with manual lenses.
So we use focus screens, and learn to focus manually (like those generations of 35/FF photographers); and with newer dSLRs we have Catch-In-Focus aka trap focus, which nails things pretty well. I've just been shooting with a Tak 55/1.8 and Chinon 55/1.7 wide open in dim light, and trap focus works just fine.
Quote: Do you really need a fast 50 ? I don't think so personally.
As always here, we get personal preferences. Some shooters have no need or use or desire for any specific type of lens. I yawn over discussions of birders' lenses, etc. (And I can't afford such goodies anyway!) We know and like what we're used to (if it doesn't bore us to death).
Still, fast lenses are prized, which is often reflected in the cost. Speed not only allows for low-light or fast-shutter shooting; IQ generally peaks at a wider f-stop. At a specific focal length, an f/1.4 lens stopped down to f/2.8 is usually sharper than an f/2.8 lens wide open. At any focal length, faster is often more desirable. (50mm seems to be THE sweet spot. Someone else can point out the other super-fasts.) Some slow lenses are incredibly crisp throughout their aperture ranges, like my little Tele-Takumar 200/5.6 -- what a gem! But it doesn't get used as much as my fat Vivitar 200/2.8. Imagine that...