Canon Patent: 15-28mm F2.8 And 17-30mm F2.8 Lenses

Canon patent application 2024101615 (Japan, published 7/30/2024) discusses optical formulas for two lenses:

• 15-28mm F2.8
• 17-30mm F2.8

From the patent literature:

• A zoom lens that is compact yet has a wide angle of view and good optical performance over the entire zoom range.
• [Background Art]There is a demand for a compact, wide-angle zoom lens as an imaging optical system used in imaging devices such as single-lens reflex cameras, video cameras, broadcast cameras, and silver-halide film cameras. As such a zoom lens, Patent Documents 1 and 2 disclose a zoom lens that is composed of a first lens group with negative refractive power, a second lens group with positive refractive power, and a subsequent lens group, which are arranged in this order from the object side to the image side.
  In a negative-lead type zoom lens, in order to miniaturize the entire system while achieving a wide angle of view and high optical performance, it is important to properly arrange the lens groups that make up the zoom lens, and the configuration and power arrangement of the first lens group are particularly important.
• The present invention provides a zoom lens that is compact yet has a wide angle of view and good optical performance over the entire zoom range, and an image pickup apparatus using the same.

Example 1

• Focal length: 15.488-27.160
• F value: 2.900
• Half angle of view: 54.532-38.744
• Image height: 17.550-20.460
• Total length: 140.161-129.964
• Back focal length: 13.270

Example 2

• Focal length: 16.482-27.299
• F value: 2.900
• Half angle of view: 52.826-38.443
• Image height: 18.100-20.460
• Total length: 141.472-132.922
• Back Focus: 14.138

Example 3

• Focal length: 17.423-31.170
• F value: 2.900
• Half angle of view: 51.201-34.556
• Image height: 18.100-20.430
• Overall length: 153.392-141.859
• Back focal length: 13.330