White paper

The!reduction!from!a!44mm!flange!back!distance!in!the!EF!mount!system!to!the!20!mm!of!the!new!RF!
mount!system!opens!important!additional!degrees!of!freedom!in!lens!designs.!!The!pivotal!innovation!
offered!by!this! short!distance,!combined!with! the! large!54!mm!diameter! RF!mount! —!is!the!freedom!to!
deploy!large!diameter!optical!elements! at! the!very!rear!of! the! lens! and! closer!to! the !large! im ag e!sensor.!!
This!adds!new!optimization!capabilities!to!the!lens-camera!imaging!interface.!
!!!!!!!!!!!!!!!!!!!!!!!
!!
Figure&8!!! The$ new $ lens$ mount$ significantly$ expands$ the$ deg rees$ of$ freedom$ in$ mo bilizing$ the$
multiple$variables$in$high-end$le n s$d e sig n $ to $im plement$a$far$greater$range$o f$zoo m $an d$prim e $lenses!
!
The!new!RF!mount!makes!possible!greater!lens!design!flexibilities:!
1. Large!diameter!rear!lens!elements!that!are!mu ch!closer!to!the!full!frame!image !sensor!—!
enhancing! overall! optical! performa nce ! (in! particular,! tighter! contro l! over! optical!
aberrations!at!image!extremities)!!
!
2. Lenses! having!the!same! s pecif ica tio n s!for!focal!length!and!maximu m!ape rt ur e!as!current!EF!
mount!lenses—but! having$ significantly$ higher$ image$ quality! —! within! the! same! size! and!
weight!
!
3. High!o p tic al!p e rfo rmance,!large !a p e r tu r e !(F 1.2)!prime!lense s!f or !fu ll!fra m e !c ameras!
!
4. Zoom! lenses! of! higher! brightness! with! constant! aperture! over! their! focal! ranges! —!while!
still!modest!in!size!and!weight!
The!following!section!is!intende d!to!co nv ey!the !critical!impo rtan ce !of!back !focus !distan ce!an d!rea r!lens!
diameter!on!the!overall!optical!performance!of!a!given!lens.!
9!