Showtime Sets Premiere Dates for Shameless and More. Aug 7, 2017 8:45 PM EDT. Showtime has set the premiere dates for its fall comedies. Shameless will return for its eighth season on Sunday, Nov. 5 at 9/8c. The season will find Frank (William H. Macy) trying to be a contributing member of society and Fiona (Emmy Rossum) discoâ¦ Read more.
Making the world better, one answer at a time. The f on a camera lens is the maximum aperture of the lens. It is sometimes listed as 1:X with X being the maximum aperture.
The diopter (or power) of a lens is defined as 1000/f, where f is the focal length of the lens measured in mm. Thus, a lens of 50mm has a diopter of +20 = 1000/50, and a +4 diopter close-up lens has a focal length of 250mm = 1000/4. A close-up lens with larger diopter value has higher magnification. However, not all lens makers mark their close-up lenses with diopter values. For example, Canon has 250D and 500D, where 250 and 500 are focal lengths of the 250D and 500D, respectively.