focallength中文

/r/photography is a place to politely discuss the tools, technique, art and culture of photography and to post topics that would be of interest to other photographers.

How does this work? Is it somehow related to the size of the projected image circle? I also noticed that micro4/3 lenses have a "sweet spot" at a lower focal length.

Focal length

How does focal length affect physical lens size? I noticed that as you go from telephoto to shorter focal lengths, lens size decreases, quite obviously. But around 35mm (?) the trend reverses, and wider angle lenses become bigger and bigger. The Canon 40mm f/2.8 for example is ridiculously small, but the Canon EF 20 mm F2.8 USM is quite huge, again.

crosshair (third-person singular simple present crosshairs, present participle crosshairing, simple past and past participle crosshaired)