What is the largest aperture on a commercially available lens?
69837
What is the fastest lens available for a DSLR?
41934
How do zoom, magnification, and focal length relate?
135149
How do camera body motors compare to in-lens motors for focusing?
15644
What is crop factor and how does it relate to focal length?
104610
What focal length lens do I need for photographing the moon?
91709
Examples in which the light maximizes the optical path length
93222
How does sensor size affect the brightness of an image given the same field of view and aperture?
47999
How do you find out the "sweet spot" of a lens?
62822
How can lens cause consistent front or back focus?
31075
What can be done using a 18-55mm lens?
40865
What should I do when I have lenses with different filter thread sizes?
79713
How can I fix a Canon lens with sand in the aperture diaphragm?
153578
Variable focal length for macro lenses?
112891
Why does the max aperture change when use Nikon 60mm AF-D Micro on D90 camera?
69119
Is the size of the entrance pupil the same as the size of the effective aperture?
1032
What is the reference point that the focal length of a lens is calculated from?
12994
Is it physically possible to build a long zoom (17-300 mm for example) at an aperture value of around 1.4 or 1.2?