<H1>Canon Patent - EF-M 55-300mm f/4.5-5.6 DO IS Lens</H1>

Canon EF 600mm f/4 DO BR lens

Canon has a strong lead in Diffractive Optics lens technology. They first introduced the EF 400mm f/4 DO IS back in 2001. I bought the lens in mid 2000s and made it my favorite wildlife photography glass for handheld shots. It was not the sharpest lens in Canon's lineup but I was willing to trade that for the unmatched mobility and flexibility the lens offered.

In September 2014, Canon released the EF 400mm f/4 DO IS II and the compromise was gone. The lens has 4 stops IS compensation, is tack sharp and still offers superb mobility. Canon demonstrated the EF 600mm f/4 DO BR lens recently at the Canon Expo in September, 2015.

Last month, Canon filed for a EF-M 600mm f/5.6 DO IS patent. Now, Egami has discovered another new Canon patent. This time it is for a EF-M 55-300mm f/4.5-5.6 DO IS lens. I am a bit puzzled how the DO version of these lenses would work in a mirrorless camera design that is already small, lightweight and consumer grade, unless Canon is planning to announce a professional grade, full frame mirrorless camera some time in the future.

Patent Publication No. 2015-232674 (Google Translated)

•     Published 2015.12.24
•     Filing date 2014.6.11
•     Zoom ratio 5.27
•     Focal length 55.04 135.00 290.01
•     F-number 4.60 5.18 6.30
•     Angle of view 13.94 5.78 2.70
•     Image height 13.66 13.66 13.66
•     Overall length of the lens 136.00 175.46 192.00
•     BF 35.50 35.50 35.50