Why do some lenses focus past infinity?
62759
Why am I allowed to turn my focusing ring beyond infinity?
86838
What do the red values mean on the distance scale of a lens?
37422
Since it's not "focal length", what is the term for the distance at which things are in focus?
109091
Why do non-constant periodic functions have no limit at infinity?
136611
Why choose an 80-200mm over an 18-200mm lens?
80219
What is the relationship between field of view and focal length for fisheye?
139331
Why doesn't exposure change when changing focal length?
75334
Why do Full Frame lenses and crop body lenses exhibit the same crop factor when used on a crop body camera?
129196
Does crop factor still apply to a vintage film SLR lens?
28095
Why does a bigger sensor lead to a shallower depth of field?
54122
Why does using a tilt-shift lens make things look miniature?
79766
What does it really mean that telephoto lenses "flatten" scenes?
56821
Why does depth of field occur?
12547
Is it okay to "ignore" small numbers in limits where $x$ approaches infinity?
17851
How does using a lens with some focal length on a full frame camera differ from using a lens with "equivalent" focal lens on a crop camera?
103113
Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range?
71754
Why do two zoom lenses set to 200mm on the same camera produce different fields of view?