Richard CanonNews / Thursday, November 29, 2018 / Categories: Canon Patents This post may contain affiliate links(s). An affiliate link means I may earn advertising/referral fees if you make a purchase through my link, without any additional cost to you. It helps to keep this site afloat. Thank you in advance for your support. If you like what we do here, maybe buy me a coffee. Canon Patent Application: DO Supertelephotos Another patent for diffractive optics (DO) super telephotos has appeared. This seems to be a subject of ongoing R&D inside of Canon, with several patent applications listed for these lenses using diffractive optics. There was a rumor about super telephotos for the RF mount using Diffractive Optics, perhaps this is related. For supertelephoto lenses, the back focus is so large, that the lens could be made for just about any mount. This patent application describes two lens embodiments, one for a 300mm 2.8 and another for a 400mm 2.8 DO supertelephoto. Focal distance 392.58 F number 2.91 a half field angle 3.15 Image height 21.64 length of the lens 363.53 BF 59.15 Focal distance 293.40 F number 2.91 a half field angle 4.22 Image height 21.64 length of the lens 274.00 BF 59.35 Japan Patent Application 2018-189878 Richard CanonNewsRichard CanonNews Richard has been using Canon cameras since the 1990s, with his first being the now legendary EOS-3. Since then, Richard has continued to use Canon cameras and now focuses mostly on infrared photography. Richard is the founder and editor of CanonNews since 2017, and has worked as a writer on CanonRumors and other websites in the past. Other posts by Richard CanonNews Contact author Facebook page Print Tags: Canon Patent Application Please login or register to post comments.