Found a great paper by Canon on lens theory, which also explains the common terminology used in lens construction. The paper also includes an extensive collection of graphs showing the optical resolution of all Canon lenses, both wide open and at F8.
Great resource if you have a Canon stills camera, or a Red One with the very soon forthcoming Birger mount (video link).
Anyone familiar with photography knows about f-stops. Calculated as Focal Length divided by Diameter (of the front lens element). The smaller the value of the f-stop, the more light passes the lens, the shorter exposure time necessary, the narrower the depth of field, the lower ASA/ISO rating necessary.
Typical f-stop values are f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 and f/32, but there are lenses with f-stops as low as 1 and as high as 128. With the arrival of automatic exoposure meters, fractional f-stops have also become the norm.
When you start using professional film lenses, you will come across the phrase T-stop. While the f-stop is a mathematically derived value, the T-stop is a calibrated value. Since lenses have optical elements, and each of these elements blocks a (tiny) amount of light, the actual amount of light coming through a lens is always lower than the f-stop value suggests.
Therefore most cine lenses are individually calibrated to give the actual amount of light transmitted, the T-stop (T standing for Transmission.) T-stops are always (slightly) higher than f-stops.
