02-25-2022, 07:39 AM
Canon has used fluorite in tele lenses since the 1970's. The two purple elements are fluorite. Nikon has, for decades, touted that thei "ED" glass was superior... until they finally were able to use fluorite element. Their FL lenses use fluorite in a similar way as Canon does.
https://imaging.nikon.com/lineup/lens/f-mount/singlefocal/Telephoto/af-s_800mmf_56g_fl_ed_vr/img/pic_003.jpg
Canon:
http://allphotolenses.com/public/files/optical/5bd01431534b42a94447ee70e118c337.gif
https://imaging.nikon.com/lineup/lens/f-mount/singlefocal/Telephoto/af-s_800mmf_56g_fl_ed_vr/img/pic_003.jpg
Canon:
http://allphotolenses.com/public/files/optical/5bd01431534b42a94447ee70e118c337.gif