Owner's Manual

Abstract&
The$Canon$ EOS$ system$is$ compris ed $ of$ EF$ lenses,$ EF-S$lenses,$ and$associated$ cameras.$$ This$system $ is$
now$thirty$years$old.$$$It$remains$robust$and$innovative.$$$T h es e$in t erc h a n ge a b le $len s-cameras$systems$
service$multiple$levels$of$the$global$imaging$marketplace$—$from$the$highest$profes sion al$lev e ls$to $th e $
aspiring$new$ photographers$within$ the$larger$ consumer$base.$ $$But$ toda y,$ bo th $ stil l$ ph o t o g raphy$ and $
motion$ imaging$are$branching$ out$in$ multiple$ directions$—$propelled$ by$a$movement$ spawned$a$ decade$
ago$w ith$ the$arrival$of$ the$hybrid$ interchangeable$lens-camera.$$Today,$even$ high $e n d$moviem ak in g $an d $
television$pro du ction $ q uite$ re ad ily$ inco rpo rate $Canon$ EOS$lenses$and$cameras$into$their$arsenal$of$image$
acquisition$tools.$Separately,$social$m edia$and$diverse$web-based$services$are$spawning$new$businesses$
and$creative$initiatives$in$still$and$motion$imaging.$$$
While$the$quest$for$more$ resolution$remains,$the$ p as t$decade$has$ also$ seen$a$rap idly$ gro wing$awareness$
of$other$dimensions$of$ image$quality$—$color$ reproduction,$dynam ic$ range,$and$ picture$capture$rates.$$
Mirrorless$cameras$have$emerged$and$have$a$growing$following.$$ Shooting$practices$are$unceasing$in$
their$diversity$and$inge nu ity.$$
Assimilating$all$of$these$movements$on$a$worldwide$scale$led$Canon$to$the$conclusion$that$a$juncture$has$
been$reached$where$new$flexibilities$were$imperative$to$expand$the$possibilities$of$the$Canon$EOS$system$
to$support$future$decades$of$both$still$and$m otion $ima gin g$—$in$all$of$their$manifesta tio n s.$$$Given$that$
optics$is$the$ very$core$ of$Canon$ led$ to$ a$co n clu s io n $ that$ new$ lenses$ offering$ important$ enhancem en ts$
must$constitute$the$ spearhead$ of$ this$initiative.$ In$ turn,$this$would$be$ predicated$on$ the$ design$of$ a$ new$
lens$mount$ th at$would$ em p ow e r$lens$d e ve lo p m e n ts $to$be $taken$to$ne w $levels.$ $$$Continuing$support$of$EF$
and$EF-S$lens es $w o u ld $b e$f a cto re d $in to $t he $n e w $s ys te m$design.$
This$ white$ paper$ will$ discuss$ in$ some$ detail$ the$ new$ lens$ mount$ design$ and$ its$ implications$ for$ an$
importa n t $ne w$genera tio n $o f$len s e s$a n d $ca meras.$
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1.0& HISTORY&OF&THE&CANON&EOS&SYSTEM&
In!198 7 !C a n o n ! lau n c h e d !a ! n ew!imaging!system!that!t ra n sformed! th e !world!o f! p h o to g ra p h ic !imaging.! The!
Canon! EOS! system! was! squarely! based! upon! an! innovative! new! lens! mount! that! had! the! following!
attributes:!
1. Large!54mm!inner!diameter!mount!—!term ed!the!EF!mount!
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2. Flange!back!distance!of!44mm!
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3. Flexible !ele c tro n ic!c o mmunica t ion !b e tween!lens !a nd !c amera.!!
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4. Large!diameter!mount!opened!broad!options!in!lens!design.!!!!
It! allowed! large! aperture ! lens! design s! that! main ta in e d ! high! optica l! performance.! Central! to! this!
design!w as! the! total! absence! of!m echanical! linkages! between! the!moving!parts! within!th e ! len se s !
and!the!camera.!
1!