Flange focal distance is the key specification in determining whether or not a particular type of lens can be adapted to any given camera.
22.
Electron lenses are designed to act in a manner emulating that of an optical lens, by focusing parallel electrons at some constant focal distance.
23.
For a thick lens made from spherical surfaces, the focal distance will differ for different rays, and this change is called spherical aberration.
24.
The VATT's mirror is unusually'fast', f / 1, which means that its focal distance is equal to its diameter.
25.
The system used a lens mount called "'A-mount "', with a flange focal distance 44.50 mm.
26.
In addition to the mechanical and electrical interface variations, the flange focal distance from the lens mount to the film or sensor can also be different.
27.
A lens designed for a small flange focal distance may not be able to focus to infinity when a lens adapter places the sensor too far away.
28.
Generally, a lens can be easily adapted to a camera body with a smaller flange focal distance by simply adding space between the camera and the lens.
29.
When attempting to adapt a lens to a camera body with a larger flange focal distance, the adapter must include a secondary lens in order to compensate.
30.
Conversely, relaxation of the ciliary muscle causes the zonular fibers to become taut, flattening the lens, increasing the focal distance, increasing long range focus.
