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Content

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Abstract 1

1.0 HISTORYOFTHEEOSSYSTEM 1

2.0 EOSSYSTEMEXTENDSTODIGITALCINEMA 2

3.0 LIMITATIONSOFTHECURRENTEOSSYSTEM 4

4.0 ACHANGINGGLOBALMARKETPLACE 4

5.0 ANIDEALLENSCAMERASYSTEM 5

6.0 EXTENDINGLENSDESIGNOPTIONS 5

7.0 KEYTOANEWGENERATIONOFLENSES—NEWLENSMOUNT 7

8.0 DETAILSOFTHENEWCANONRFMOUNT 8

9.0 CHALLENGEOFMANAGINGLENSABERRATIONS 10

10.0 NEWCONCEPTSUNDERLYINGRFLENSES 1210.1 NewFeatureUniquetoRFLenses 12

10.1.1 ControlRing 1210.1.2 ApertureBladeControl 1210.1.3 FocusRingRotationDirectionChange 1310.1.4 EnhancedElectronicCommunicationbetweenLensandCamera13

11.0 INTRODUCTORYFAMILYOFRFLENSES 13

11.1 RF28-70mmF2LUSM 1411.2 RF50mmF1.2LUSM 1911.3 RF24-105mmF4LISUSM 2211.4 RF35mmF1.8MACROISSTM 27

12.0 EFLENSMOUNTADAPTERS 30

13.0 EOSRLENS-CAMERASYSTEM 3213.1 EnhancedImageStabilizationSystem 3213.2 DigitalLensOptimizer(DLO)System 3413.3 DualPixelCMOSAFSystem 3613.4 ComparisonofEOSRlens-camerasystemwithEFlensandDSLR 39

14.0 SUMMARY 41

Abstract

TheCanonEOS system is comprisedofEF lenses, EF-S lenses,andassociated cameras. This system isnowthirtyyearsold. Itremainsrobustand innovative. These interchangeable lens-camerassystemsservicemultiple levelsoftheglobal imagingmarketplace—fromthehighestprofessional levelstotheaspiringnewphotographerswithin the larger consumerbase. But today, both still photographyandmotionimagingarebranchingoutinmultipledirections—propelledbyamovementspawnedadecadeagowiththearrivalofthehybridinterchangeablelens-camera.Today,evenhighendmoviemakingandtelevisionproductionquitereadilyincorporateCanonEOSlensesandcamerasintotheirarsenalofimageacquisitiontools.Separately,socialmediaanddiverseweb-basedservicesarespawningnewbusinessesandcreativeinitiativesinstillandmotionimaging.

Whilethequestformoreresolutionremains,thepastdecadehasalsoseenarapidlygrowingawarenessofotherdimensionsof imagequality—color reproduction,dynamic range,andpicturecapture rates.Mirrorless camerashaveemergedandhaveagrowing following. Shootingpracticesareunceasing intheirdiversityandingenuity.

AssimilatingallofthesemovementsonaworldwidescaleledCanontotheconclusionthatajuncturehasbeenreachedwherenewflexibilitieswereimperativetoexpandthepossibilitiesoftheCanonEOSsystemtosupportfuturedecadesofbothstillandmotionimaging—inalloftheirmanifestations.Giventhatoptics is the very coreofCanon led toa conclusion thatnew lensesoffering importantenhancementsmustconstitutethespearheadofthisinitiative.Inturn,thiswouldbepredicatedonthedesignofanewlensmountthatwouldempowerlensdevelopmentstobetakentonewlevels.ContinuingsupportofEFandEF-Slenseswouldbefactoredintothenewsystemdesign.

This white paper will discuss in some detail the new lens mount design and its implications for animportantnewgenerationoflensesandcameras.

1.0 HISTORYOFTHECANONEOSSYSTEM

In1987Canonlaunchedanewimagingsystemthattransformedtheworldofphotographicimaging.TheCanon EOS system was squarely based upon an innovative new lens mount that had the followingattributes:

1. Large54mminnerdiametermount—termedtheEFmount

2. Flangebackdistanceof44mm

3. Flexibleelectroniccommunicationbetweenlensandcamera.

4. Largediametermountopenedbroadoptionsinlensdesign.

It allowed large aperture lens designs that maintained high optical performance. Central to thisdesignwas the total absenceofmechanical linkages between themovingpartswithin the lensesandthecamera.

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Alloperationalfunctionsweresupportedbytheelectricalcommunicationbetweenthelensandcamera.This communication allowed focusing motors to be optimally positioned within each individual lensdesign, which supported fast auto focus systems. The aperture control was also electronic whichsupported auto-aperture functionalities. In the ensuing decades these core design strategiesempoweredaprogressive imagingevolution thatwitnessed theemergenceofanextraordinarybroadrangeofzoomandprimelensesthatwereflankedinitiallybySLR35mmfilmcamerasandultimatelythearrivaloftheall-digitalDSLRcameraintheearly21stcentury.

In1995thefirstlenswithbuilt-inimagestabilizationsystembecamepossiblebaseduponthatelectroniccommunication (the EF75-300mm f/4-5.6 ISUSM). The lens-cameramovements detectedwithin thelens itself are processed and control signals generated that actuate correction opticswithin the lens.That large diametermount and the electronic communication continue to empower new features inboth lensandcameratothisday. AndthepacedexpansionofEF lensesandcamerasovertheyearsspeaksagreatdealaboutthesuccessofthisremarkabledesignstrategy.

Figure 1 Threedecadesof theCanonEOSsystemhas seenan impressiveevolutionof lensesandcamerasthatpresentlyserveaworldwidemarketatmanylevels

2.0 CANONEOSSYSTEMEXTENDSTODIGITALCINEMA

Today’sworldproductioncommunity—both theatricalmotionpictureandepisodic television—willutilize all manner of lens-camera combinations to achieve their creative aspirations and meet theirproduction budgets. Major movies have been produced that incorporated DSLR’s coupled to digitalcinemalensesandhigh-enddigitalcinemacamerasusingEFlenses.

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Figure2 Theglobalproductioncommunitiesfreely“mix‘nmatch”lensesandcameras

In 2011 Canon leveraged the vast accumulation of experiences in the broadcast television opticsbusiness and that of the now firmly establishedCanon EOS system to enter the digital cinemaworldwithafamilyofhigh-endprofessionaldigitalcinemalenses(bothprimesandzooms)andcameras—theCanonCinemaEOSsystem.ThissystemwasdesignedtoutilizetheEFmount—whilealsoofferingtheoption of the established cinematography PL mount on the higher end products within this family.Whiledistinctlydifferentintheirrespectivetargetmarketsbothlens-camerafamiliesbenefitedgreatlyfrom the shared technologies. This systemization offered the productionworld great flexibilities incombiningA-CameraswitharangeofchoicesinB-cameraandC-cameraoptions.

Figure3 SuggestingthetechnologicaloverlapbetweentheCanonEOSstillphotographysystems(leftandcenter)andtheCanonCinemaEOSmotionimagingsystemontheright

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3.0LIMITATIONSOFTHECURRENTEOSSYSTEM

Assessing thecurrentEOS system in thecontextof future considerationsexposes some limitationsasfollows:

1. Insufficient flexibilities inmountdiameter andback focusdistance to accommodateall oftheincreasinglydiverserequirementsinzoomandprimelenses

2. Limitedspeedoftheelectroniccommunicationbetweenlensandcamera

3. Limited electronic channels between lens and camera to accommodate new operationalaspirations

4. Constraintsinsensor-basedAFoperationalcapabilities

Collectively, these considerationsmake a compelling case for amore encompassing approach to theinterchangeable lens-camera system going forward. A new lens system is pivotal to form anunderpinningcoretothenewEOSRsystem.

4.0 ACHANGINGGLOBALMARKETPLACE

Digital imaging has been with us for almost a quarter century. But, the past decade has seenextraordinary advances in both image performance and creative flexibilities offered by contemporarylensesandcameras.Theformerlinesseparatingstillandmotionimagingareblurred,imageresolutionhassoared,andenduserdemandsformoreoperationalempowermentsareunceasing.Applicationsofinterchangeablelens-camerasystemscontinuallybroaden.

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5.0 ANIDEALLENS-CAMERASYSTEM

Three decades after the debut of the Canon EOS system Canon believes that new and broadeningmarketplace dynamics require an extension to the original design premise of the EF interchangeablelens-camerasystem.Anideallens-camerasystemintendedforfutureyearsinimagingwouldincludethefollowingcontemporaryconsiderations:

1. Emergingpopularityofthefullframeimagesensor

2. Anticipatedprogressiveelevationofsensorresolution

3. Questforhigherexposureranges

4. Increasing diversity and sophistication of end-users seeking extended operationalfunctionalities

Alloftheseconsiderationsbeardirectlyonthelensandlensmountdesigns.

6.0 EXTENDINGLENSDESIGNOPTIONSThere continues to be an inexorable growth in the needs and aspirations of the multiple creativecommunitiespresentlyengagedinbothstillandmotionimaging.Widelydifferingneedsinzoomsandprimes encompass a spectrum of optical performances, size/weight considerations, and operationalfeatures—oftenrequiringapragmaticbalancebetweenthesethreecentralspecifications—Figure4.Longfocalrangescombinedwithawideaperture—asrequiredforsportscoverage—mightmilitateagainstachievementofthehighestopticalperformance.Lensesintendedforportraituremightassignthe top priority to overall optical performance specifications — perhaps at a cost of some limit toapertureandmaybesizeandweight.Thevariationsindiverseshootingrequirementsareendless.

Figure4 Thetotalityoflensdesignentailsmanyparametersthatbearuponthreekeycriteria

If theareaof the triangle inFigure4 reflectsallof theoptical,optomechanical,andelectronicdesignparametersavailabletothelensdesigners,thenmaximizingthatareaoffersgreateroptionsinfavoringcertainspecifications,oralternatively,optimizingthebalancebetweenthethreecorespecifications.

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Inthatcontext,seekingtheideallensforagivenshootingapplicationmustenvisagebroadeningflexibilitiesinopticalandsystemdevelopmentsaccordingtothefollowing:

1. Higher Optical Performance — to accommodate multiple future enhancements in cameraperformance

2. Increasedopticalspeed—forspecificlenses

3. EnhancedOperational Specifications— such as focal length ranges,maximum aperture, andtheircontrols

4. Meeting demands in Size and Weight Specifications — which can be critically important tocertainformsofshooting

The ideal lens for a given shooting application typically seeks optimization of one of the threespecifications, generally accompanied by a desire to also elevate the priority of a second of thesespecifications—assuggestedinFigure5. Notethattheareaofthetriangleremainsconstant—buttheincreasednumberofdesignparametersoffersnewflexibilitiestoachievethesehigherdesigngoals.For other lens designs, there are also more options available to support a more favorable balancebetweenthethreespecifications.

Figure5 Illustratingthediversityinlensdesignsrequiredtomeetcontemporaryimagingneeds

OverthedecadestheCanonEOSEFlensdesignshavesupportedreasonableflexibilityinmanagingoftenconflictingrequirements—primarilybecauseofthelarge54mmmount.Ontheotherhand,thelonger44mmflangebackdistance(distancefromareferencepointonthelensmounttotheimagesensor)hashamperedcertaindegreesoffreedominsomelensdesigns.Thatspacebetweenthefinallenselementand the image sensor (especially in the case of the large full frame image sensor) is invaluable toachieving optimization of the projected image performance. Accordingly, central to achievingextensionsinlensdesignoptionsisaradicalredesignofthelensmount.

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7.0 KEYTONEWLENSGENERATION—NEWLENSMOUNTCentraltotheeffectiveimplementationofthestrategytoextendthepotentialoftheEOSsystemforthefuture is anew lensmount. Canonhasdevelopedamount thatholdshighpromiseof sustaining farmoreflexiblelensdesignsoverthelongterm—thenewRFmount.

Figure6 Thenew lensmount isdesignedtoempowernewflexibilities in lensdesignandanewgenerationofmirrorlesscameras

Considerationsthatguidedthenewlensmountdesign:

1. Totallynewmount—butonethatretainsthelarge54mminnerdiameteroftheEFmount

2. AccommodatecurrentCanonEOSimagesensorsizesuptoFullFrame36mmx24mm

3. Leveragetheshorter20mmflangebackdistanceoftheMirrorless(ML)systemtosupportnew

opticaldesigns

4. Significantelevationoftheelectroniccommunication inthenewinterchangeable lens-camera

system—increasingthenumberofcontactpinsfromeight(currentEF)totwelve

5. Accommodationofexisting(andnew)EFlenses—withvirtuallynoperformancecompromises

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8.0 DETAILSOFTHENEWCANONRFMOUNT

Figure7ShowingnewRFmount(ontheright)sidebysidewiththeexistingEFmount(ontheleft)

RFmountisanewmountthatmaintainstheadvantagesofafullyelectroniclarge-diameterEFmountswhileadditionallyofferinganoptimaldiameter,flangeback,andbackfocustomorefullycapitalizeonopticalcharacteristicsofafull-framemirrorlesssystems.

Like the EF mount, a 3-tab bayonet mount is used in the RF mount. However, to prevent incorrectattachment,bayonettabsareindifferentpositionsthantheyareontheEFmounts.Forthisreason,EFlensescannotbeattacheddirectly.Inuse,thenewRFmountalsoresemblesexistingEFmounts.Lensesarerotatedtoanangleof60°forattachmentorremoval,andthelenslockpinisinthesamepositionason an EFmount (at the 3 o’clock position, as viewed from the front of the camera), with the sameamountofprotrusionandmovement.

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Thereductionfroma44mmflangebackdistanceintheEFmountsystemtothe20mmofthenewRFmountsystemopens importantadditionaldegreesof freedomin lensdesigns. Thepivotal innovationofferedbythisshortdistance,combinedwiththelarge54mmdiameterRFmount—isthefreedomtodeploylargediameteropticalelementsattheveryrearofthelensandclosertothelargeimagesensor.Thisaddsnewoptimizationcapabilitiestothelens-cameraimaginginterface.

Figure8 The new lens mount significantly expands the degrees of freedom in mobilizing themultiplevariablesinhigh-endlensdesigntoimplementafargreaterrangeofzoomandprimelenses

ThenewRFmountmakespossiblegreaterlensdesignflexibilities:

1. Largediameterrear lenselementsthataremuchclosertothefull frameimagesensor—enhancing overall optical performance (in particular, tighter control over opticalaberrationsatimageextremities)

2. LenseshavingthesamespecificationsforfocallengthandmaximumapertureascurrentEFmount lenses—buthaving significantly higher image quality—within the same size andweight

3. Highopticalperformance,largeaperture(F1.2)primelensesforfullframecameras4. Zoom lensesofhigherbrightnesswith constant apertureover their focal ranges—while

stillmodestinsizeandweight

Thefollowingsectionisintendedtoconveythecriticalimportanceofbackfocusdistanceandrearlensdiameterontheoverallopticalperformanceofagivenlens.

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9.0 THECHALLENGEOFMANAGINGLENSABERRATIONS

Optical aberrations are an inescapable reality of each and every elementwithin all lenses. Thewell-knownSeidelmonochromaticaberrations areimagedefectsassociatedwiththefundamentalbehavioroflightrays—ofallwavelengths—passingthroughalenselement.Thesemonochromaticaberrationsinclude spherical aberration, coma, astigmatism, curvature of field and geometric distortion.Collectively,theyareoftentermedthe“defocusingdistortions”becausetheycumulativelyconspiretoimpairimagesharpness(especiallyasalensirissettingapproachesmaximumaperture). Inadditiontomonochromaticaberrations,thereareadditionalaberrationsassociatedwithcoloredlightthat are wavelength-dependent. Different wavelengths of light encounter a different index ofrefractionwithinagivenopticalmaterial,referredtoasdispersion.Thesearetechnicallydescribedbytwoaberrations:(a)Longitudinalchromaticaberration(differentfocusplaneforconstituentcolors)thatproduce an unwanted colored flare; and (b) Lateral chromatic aberration (becausemagnification ofdifferent wavelength rays vary they cause an associated variation in the lateral magnification thatproducinganeffectivecolormisregistrationintherecordedvideoorstillimage).Light rays passing through the center of a multi-element lens will exhibit a modest degree of theseaberrations.However,aslightraysfromtheextremitiesofaframedsceneenterthelensatincreasingangles and are ultimately focused on the extremities of the CMOS image sensor image plane, theaberrationscanallrapidlyincrease.Themoreacutetheangleofthoseraysbeingprojectedontothesensor— the greater the level of aberrations. For a large image sensor like Full Frame this poses aparticularchallengetothelens—especiallywhenthecornersoftheimagecontainhighdetail.

Figure9Conceptofahypotheticallensimagingahighlydetailedscene—andtheimportanceofthebackfocusdistanceandrear lensdiameterontheangleofaraybundleprojectingontothecornersoftheimagesensor

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Twokeydimensionsplaya significant role in thequalityof the final imageprojectedon to the imagesensor—theyaretheback focusdistanceandthediameterof the final lenselement. Figure9 isasimplisticillustrationoftheircumulativeeffectontheangleoftheraybundlelandingontheextremitiesoftheimagesensor.Thecoloredcirclesidentifyraybundlesaffectingimageperformanceintheimagecentralzone(red)andintheimageextremities(blue).Astherefractive index,or“bending”powerofthelens increases,variousaberrationstendto increaseeasily.If the rear lens is larger, ray bundles can be projected more gently to the larger image sensor andsuppressionoftheoccurrenceofvariousaberrationscanbemade.Ontheotherhand,thesmallertherear lens is, it isnecessary that the refractionof the rayhaveamoreacuteangle to the larger imagesensorbystrongerrefractivepowerofthelens,whichcanleadtomorevariousaberrations.The criticality of the back focus distance is simplistically illustrated in Figure 10. The top imagesimulatesa lenshavinga longback focusdistance—suchasexists in thecurrentCanonEOSEF lenssystem.Manydesignstrategiesaremobilizedforthemanydifferenttypesofzoomandprimelensesinthis family of lenses to counteract the effect of aberrations. One key strategy is to use a large lenselement in the frontof the lens system tomore independentlyandgentlymanage thedegreeof theangleoftheemerginglightraybundleprojectedontotheimagesensor.Thisgenerallywillextendthelengthoftheoverallopticalsystem.

If,however,thebackfocusdistancecouldbeshortened,thisthenopensupspacetomovethefinallenselementclosertotheimagesensor—and ifthiselementismadelargethenanequivalentcontrolforaberrationsoftheraybundleprojectedontothecorneroftheimagesensorcanbemade—asshowninthelowerimageinFigure10.

Figure10 Showingtwoalternativesinlensdesigntoindependentlyandgentlycontrolaberrationsoftheraybundleprojectedontothecorneroftheimagesensor

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10.0NEWCONCEPTSUNDERLYINGRFLENSES10.1NewFeatureUniquetoRFLenses

The new RF lenses represent a quite radical step forward in lens designs that anticipate the futureimagingneedsofanincreasinglysophisticatedenduser.

10.1.1ControlRing

Asignificantnewinnovationisincorporatedintothedesignoftheselenses—aspecialknurledcontrolring,which inthe initialRF lensembodiments ispositionedattheveryfrontofthe lens—beforethefocusingcontrolring,asshowninFigure11.Itcapitalizesontheaugmentedelectroniccommunicationbetweenlensandcamerathatiscentraltothenewlensdesign.Thepurposeoftheringistofacilitateintuitive and flexible access to adjustment of Aperture value / Shutter speed / ISO and ExposureCompensation.Theparticularfunctionselectionisperformedin-cameraintheCustomFunctionmenu.Inthenewlensesdescribedinthispaper,astheringisrotateditclicks(differentnumberofclicksperrevolution for different RF lenses) which serves to provide a sensory cue while the photographer islookingthroughtheviewfinder.Thedirectionofrotationcanbesettosuituserpreference.And,usershaveachoiceofwhethercontrolringrotationactuallychangesexposureonlywhentheshutterbuttonispressedhalf-way(tominimizeriskofinadvertentchanges),ortohaveanymovementdirectlyimpactexposure(withnoneedtofirstholdtheshutterbuttonhalf-waydown).

Figure11 ShowingthenewControlRingthatextendsoperationalflexibilitiesforthephotographer

A newmicroprocessorwithin the lens has improvedprocessing capability togetherwith lower powerconsumption and high-speed communication. The increased capacity of the built-in memory allowsmoredata tobestored,enablinghighlyaccurate lenscontroland imagecorrection. This isespeciallyimportantfortheDigitalLensOptimizerfeatureoftheRFsystem.

10.1.2ApertureBladeControl

The new family of RF lenses incorporates an important new feature that automatically closes theaperturebladesoneortwostepswiderthanthesmallestpositionuponpowerclosedown.Thishelpsprotectthecameraimagesensorandshutterbladesfromdamaginghighintensitylightsources.

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10.1.3 FocusRingRotationDirectionChangeTheRFlensesallincorporateanabilitytochoosethedirectionofrotationofthemanualfocuscontrol.Inplaceofadirectmechanicalconnectionfromfocuscontrolringtotheactualfocusingoptics,througha threaded, allmechanical helicoid, the systemuses a focus ring connected to a seriesofmany veryfine,electronic contacts. There'snodirect,mechanical connectionatall to thegroup(s)ofelementsthatmovethefocusingelement.Rotatingthefocusringsendsaseriesofveryspecific,finesignalstothesecontacts.Theseareconvertedintosignalstothesamefocusmotor(USM,NanoUSM,etc.)that'susedforautofocus.Themotornowdrivesthelenstochangefocus.

InherenttothissystemthereisacustomfunctiontochangeManualFocusdirection,whichcanbeaninvaluableassettouserstransitioningtoCanonfromcompetitivesystems.Thisalsobenefituserswhoutilizeafollowfocussystem(externalgearsandaknobtocontrolfocus).

10.1.4EnhancedElectronicCommunicationbetweenLensandCameraThe new RF mount uses 12 contacts instead of the 8 contacts of the EF lenses for lens-cameracommunication. New communication protocols and dedicated communication channels areincorporated—whichsupportlargedatatransfersatveryhighspeedscomparedtocurrentEFsystem.ThenewRFsystemdesignanticipatesongoing innovations in futurecamerasaswellas lenses. Evenwiththesechanges,fullsupportandcompatibilityforexistingCanonEFandEF-Slensesremain.

11.0 INTRODUCTORYFAMILYOFCANONRFLENSESThiswhitepaperwilloutlinefourlensesthatconstitutetheintroductoryphaseofthenewRFsystem:

10.1 RF28-70mmF2LUSM10.2 RF50mmF1.2LUSM10.3 RF24-105mmF4LISUSM10.4 RF35mmF1.8MACROISSTM

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11.1 RF28-70mmF2LUSMRF28-70F2LUSMisalarge-diameter,standardLzoomlenswithabrightF2.0constantapertureacrosstheentirezoomrange—thenew28-70mmF2. Thelens is intendedforprofessionalphotographers,high-endamateurs,andlow-lightmoviemaking.Itembodieshigh-speedautofocusfunctionality,andaControlRingforfunctionalassignmentofexposurecontrols.

Figure12 ThenewRF28-70F2LUSM—acompact28-70mmF2.0zoomlenshashighoverallopticalperformanceandexcellentoperationalempowerments

Thelensiscomprisedofnineteenelementsinthirteengroups.Thelargediametermountandtheshortback focusareused toparticularadvantage togain thehigherbrightnessofF2.0. These two factorsmean the front section of the lens can by physically much smaller than conventional EF lensarchitecture.Thestrategicdispositionoffourasphericlenselements(showninlightgreen)inFigure13helpstominimizeastigmatism,sphericalaberrationandgeometricdistortion,whilethetwoUDandoneSuperUDelements(darkgreen)helpcurtailthelongitudinalandlateralchromaticaberrations.

Figure13 TherearethirteengroupsmadeupofatotalofnineteenlenselementsintheRF28-70mmF2LUSMlens

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The new RF mount made possible a zoom lens having an ultra-large dimeter and a constant F2.0aperture across the entire zoom range. The F2.0 maximum aperture creates an excellent creativebokeh.

Figure14 ShowingtheoperationalcontrolsontheRF28-70mmF2LUSMlens

This remarkable zoom lens is represents a significant step forward in terms of the F2.0 constantaperture,generouszoomrange,andasizeandweightthatwouldnothavebeenpossibleinanEFlens.Itisidealforhandheldshooting.

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11.1.1MTFCharacteristicsoftheRF28-70mmF2LUSMLens

TheMTFcurvesinFigure15showthebehaviorofthislensmeasuredatfourdistancesfromtheimagecenter.Twospatialfrequenciesareused—one,atthelow10linepairspermillimeter(LP/mm)whichis an importantmeasure of the contrast of the lens, and the second is at a higher 30 LP/mmwhichindicatesresolvingpower.Twoseparatemeasurementsaremadeforeachatrightanglestoeachother.Theterm“imageheight”referstohowfartowardanyofthefourcornersoftheimageameasurementistakenasshowninthefigurebelow.

Figure15MTFcharacteristicsoftheRF28-70mmF2LUSM—thewideaperturesettingontheleftandtelephotoonright

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11.1.2MTFofRF28-70mmF2LUSMandEquivalentEFZoomsFigure16showstheMTFcurvesforthenewEF28-70mmF2LUSMontherightcomparedwiththoseoftwoestablishedEFzoomlenses—withallthreelensessetatmaximumaperture.Ofspecialnotearethefollowing:

1. 10Lp/mmSagittalofthenewF2lensisveryclosetothatoftheEF24-70mmf/2.8LIIUSMlens(slightlybetteratmaximumimageheight)andismuchhigherthantheEF24-70mmf/4LISUSMlensatmaxheight

2. 10Lp/mmMeridionalapproximatestheperformanceofEF24-70mmf/2.8LIIUSMattheimageextremity,butitismuchbetterthantheEF24-70mmf/4LISUSMlensatmaximumimageheight

3. 30Lp/mmSagittalbehaviorisconsiderablybetterthantheEF24-70mmf/2.8LIIUSMatmaximumimageheightandisfarhigherthanthatoftheEF24-70mmf/4LISUSM

4. 30Lp/mmMeridionalcurvefortheRF28-70mmF2LUSMishigherfromimagecentertoanimageheightof15mmthanbothEFzoomlensesandisequivalenttoEF24-70mmf/2.8LIIUSMatimageextremity—butmuchbetterthanEF24-70mmf/4LISUSMattheextremity

Figure16 ComparativeMTFBehaviorofRF28-70mmF2LUSMversusequivalentEFzoomlensesatthewideanglesetting(alllensessettomaximumaperture)

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Figure17showstheMTFcurvesforthetelephotoendofallthreezoomlenses.

1. 10Lp/mmSagittalisslightlyhigherthanbothEFlensesatthefarcornersoftheimage

2. 10Lp/mmMeridionalisessentiallyequivalenttothatoftheEF24-70mmf/2.8LIIUSMbutishigherthanthatofEF24-70mmf/4LISUSM

3. 30Lp/mmSagittalishigherthanbothEFlensesatthe22mmheight

4. 30Lp/mmMeridionalisessentiallyequivalenttothatoftheEF24-70mmf/2.8LIIUSMoutto15mmheight—butishigheratthe22mmextremity

5. 30Lp/mmMeridionalishigherthanthatoftheEF24-70mmf/4LISUSMoutto15mmaway

fromimagecenter—andissignificantlyhigheratthe22mmextremity

Figure17ComparativeMTFBehaviorofRF28-70mmF2LUSMversusequivalentEFzoomlensesatthetelephotoendoftheirrespectivezoomranges

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11.2 RF50mmF1.2LUSMThis is a large diameter standard single-focus lens employing the new standard RF mount. At itsmaximumapertureofF1.2thelensmaintainshighsharpnessatimagecenterwithwellcontrolledfalloffofMTFtowardtheimageextremities.Thelensisdesignedtoextendthecreativephotoexpressivenessforprofessionalphotographersandhigh-endamateurs.

Figure18 ThenewRF50mmF1.2LUSMfeatureshighoverallopticalperformanceandinnovativeoperationalfunctionalities

Thelensisatotallynewopticaldesign,comprisedoffifteenelementsinninegroups.TherearelementscapitalizeontheshortflangebackoftheEOSRsystem—theirlargesizecontributingtothehighopticalperformance. Thefirstelevenelementsconstitutethefocusingoptics. The lenshasaminimumfocaldistanceof40cm(15.7inches)andmaximummagnificationis0.19x.

Figure19 ShowingtheninegroupsmadeupofatotaloffifteenlenselementswithintheRF50mmF1.2LUSMlens

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The lens deploys three high-refraction aspheric elements— shown in green in Figure 19. ChromaticaberrationsareminimizedusingtheUDelement(darkgreen).

FlareandghostingareparticularlywellcontrolledusingCanon’sSuperSpectraCoatings—withtheAirSphere Coating (ASC) technology on one critically positioned lens element shown in Figure 19. AirSphereCoating isananti-reflectiontechnologythatcombinestheexistingvapor-depositedmulti-layercoatingswithanultra-lowrefractiveindexoutermostlayer.ASCsignificantlyreducesflareandghostingthat cannot be prevented with conventional vapor-deposited multi-layer coatings, improving anti-reflectionperformance.

ThislensisastrikingexampleofthepowerfulnewflexibilityofferedbythenewRFmountinachievingtheF1.2brightnessinacompactlens.ToachievethislevelofopticalqualityinanF1.2designwiththestandardEFmountwouldhaveentaileda significantly larger lens. The lensenables close-ups fromaclosestfocusingdistanceof1.31feetandproducesbeautifulbokehfromacircularaperturewitha10-bladeiris.

ThefocusingactuatorisaringUSM(ultrasonicmotor). Thelenshasa10-bladeapertureactuatedbyEMD(ElectroMagneticDiaphragm)whichsupportsbeautifulrenderingofout-of-focusbackgrounds.

Thefrontfiltersizeis77mm.

Figure20 Showing the Focus Mode and Focus Distance Range Selector switches while alsooutliningwheredustandwatersealingdesignprecautionshavebeenimplemented

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11.2.1MTFCharacteristicsoftheRF50mmF1.2LUSMlenscomparedtoEFLensesFigure21showstheMTFcharacteristicsoftheRF50mmF1.2LUSMlensatthemaximumrelativeaperturesettingofF1.2.

Figure21The10and30Lp/mmMTFcurvesforRF50mmF1.2LUSM

Figure22ComparingtheMTFcharacteristicsoftheRF50mmF1.2LUSMlenswithtwo50mmEFlenses

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1. 10Lp/mmSagittaloftheRF50mmF1.2LUSMlensmaintainsasignificantlyhigherMTFacrossthetotalimageheightcomparedtobothEFlenses(andespeciallycomparedtotheEF50mmf/1.2LUSM)

2. 10Lp/mmMeridionalexhibitsanexcellentMTFcharacteristiccomparedtobothEFlenses

3. 30Lp/mmSagittalexhibitsahigherandmorecontrolledMTFacrossthetotalimageheightthanthetwoEFlenses

4. 30Lp/mmMeridionalcurveforRF50mmF1.2LUSMlensalsoshowsanexcellentcharacteristicthatissuperiortothatofbothEFlenses

11.3RF24-105mmF4LISUSMRF24-105mm F4 L IS USM is amedium-diameter standard zoom lenswith an F4.0 constant apertureover the entire 24-105mm focal range. Its minimum aperture is F22. The lens is intended forprofessional photographers, high-end amateurs, and low-budget moviemaking. It embodies anenhanced image stabilization system, high-speed auto focus functionality, and the innovative newknurledcontrolringforfunctionalassignmentofexposurecontrols.

Figure23 ThenewRF24-105F4LISUSMhashighoperationalfunctionalityandimpressiveopticalperformanceinanunusuallycompactsize

Evenwiththebuilt-inimagestabilizationsystemthesizeandweighthavebeenminimizedtoalloweasyhand-held shooting. Minimum focusing distance is 0.45m (1.48 feet). The lens is comprised ofeighteen elements in fourteen groups. This is a particularly interesting example of unusually largediameterrearelementscapitalizingontheshortflangebackoftheRFsystem—withthiscombinationcontributingtothehighopticalperformanceoftheimageprojectedontoalargeFullFramesensor.

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Figure24 ShowingthefourteengroupsmadeupofatotalofeighteenlenselementsintheRF24-105mmF4LISUSMlens

Strategicdispositionofthreeasphericlenselements(showninlightgreeninFigure24helpscorrectforastigmatism,sphericalaberration,andgeometricdistortion.TheUDlenselementshownindarkgreenhelpsminimizebothlateralandlongitudinalchromaticaberrations.TheCompensationOpticsgroupinthecenteristhelenselementgroupwhichperformstheimagestabilizationcorrection.

Figure25 ShowingtheZoom,Focusing,andControlringsandthevariousmodeswitches

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Because the focusing element (“focus lens” in Figure 24 above) is small and lightweight the focusingactuator deploys a Nano USM (new Thin-type). This motor uses the basic Ultrasonic principle, ofextremely controlled, finevibrationsproducedby runningcurrent througha specificmetaldevice. Inthiscase,the"device"looksalmostlikeatinymetalbandage,withlittleprojectingnubsoneitherside— Figure 26. These in turn contact a sliding surface, and vibrations are transformed into linearmovement, and a lens element guided by a control bar moves fore or aft to drive focus in eitherdirection.

Figure26 ShowingtheNanoUSMusedtoactuatethefocusingelementinthenewRF24-105mmF4LISUSMzoomlens

TheNanoUSMisveryquickandquietandisparticularlywell-suitedtostop-and-startoperationthat'squitecommoninvideoshooting.ItalsohelpsensuremuchsmootherAFduringvideoacquisition.

11.3.1MTFCharacteristicsoftheRF24-105mmF4LISUSMZoomLens

Figure27 MTFcharacteristicsoftheRF24-105mmF4L ISUSM lensatboththewideendandthetelephotoend

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Figure28showstheMTFcurvesforthenewRF24-105mmF4LISUSMontheleftcomparedwiththoseoftwoestablishedEFzoomlenses—forthewideendoftheirrespectivezoomranges.Ofspecialnotearethefollowing:

1. 10Lp/mmSagittalisslightlylowerthanthatoftheEF24-105mmf/4LISIIUSMlensexceptattheextremecornersoftheimage

2. 10Lp/mmMeridionalmaintainsahigherMTFfromimagecentertoaheightof15mmthanbothEFlenses—anditapproximatestheperformanceofEF24-105mmf/4LISIIUSMattheimageextremity

3. 30Lp/mmSagittalbehaviorisslightlybetterouttoanimageheightof15mmthantheEF24-105mmf/4LISIIUSMbutishigherthanthatoftheEF24-105mmf/3.5-5.6ISSTM

4. AtimageextremitytheRF24-105mmF4LISUSMmaintainsahigherSagittalMTFthanbothEFzooms

5. 30Lp/mmMeridionalcurvefortheRF24-105mmF4LISUSMishigherfromimagecentertoanimageheightof15mmthanbothEFzoomlensesandisequivalenttoEF24-105mmf/4LISIIUSMatimageextremity—butmuchbetterthanEF24-105mmf/3.5-5.6ISSTM

Figure28 ComparativeMTFbehaviorofRF24-105mmF4LISUSMversusequivalentEFzoomlensesatthewideanglesetting

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Figure29showstheMTFcurvesforthenewRF24-105mmF4LISUSMontheleftcomparedwiththoseoftwoestablishedEFzoomlenses—forthewideendoftheirrespectivezoomranges.Ofspecialnotearethefollowing:

1. 10Lp/mmSagittalforRF24-105F4LISUSMisslightlyloweracrosstheimageheightthanthatoftheEF24-105mmf/4LISIIUSMexceptatmaximumimageheight

2. 10Lp/mmMeridionalexhibitsalowerMTFfromimagecentertoaheightof15mmthanbothEFlenses—anditapproximatestheperformanceofEF24-105mmf/3.5-5.6ISSTMattheimageextremity

3. 30Lp/mmSagittalbehaviorisslightlyhigheratanimageheightof15mmthanbothEFlenses

4. 30Lp/mmSagittalisslightlyhigherthanbothEFlensesoutto15mmheight

5. 30Lp/mmMeridionalcurveforRF24-105mmF4LISUSMisverysimilartobothEFlensesoutto15mmimageheightandatimageextremityishigherthanEF24-105mmf/3.5-5.6ISSTMandslightlylowerthanEF24-105mmf/4LISIIUSM

Figure29 ComparativeMTFbehaviorofRF24-105mmF4LISUSMversusequivalentEFzoomlensesatthewideanglesetting

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11.4RF35mmF1.8MACROISSTMRF35mmF1.8MACROISSTMisawideanglemacrolensemployingthenewstandardRFmounthavingamaximum aperture of F1.8 and a 0.5xmagnification. It has aminimum aperture of F22. This is amoderate wide-angle lens with a compact overall design, ideally suited to traditional candid streetphotographyand low-light imaging. It combinesbeautifullywith the smallermirrorless cameraasalightweight, travel and location oriented lens for serious enthusiasts. In spite of its F1.8maximumaperture, it doubles as a true macro lens, with ability to fill the frame with a subject as small as abusiness card at its nearest focus distance. Finally, it offers optical Image Stabilization, furtherenhancingitsabilitiesinlow-lightsituations.

Figure30 ThenewwideangleRFlens—RF35mmF1.8MACROISSTM

Thelensiscomprisedofelevenelementsinninegroups—Figure31.TherearelementscapitalizeontheshortflangebackoftheRFsystem—havingaparticularly largediametercontributingtothehighoptical performance. The first nine elements constitute the focusing optics, and these aremoved intandemasfocusingiscarriedout.Anasphericelementinthefocusinggroupreducesaberrationsduringfocusing. The lens is a compact, lightweight, and large-diameter wide-angle lens with the ability toprovide 0.5x macro shooting, by using front-lens focus together with forward placement of thediaphragmandalighterfocusgroup.Thelenshasaminimumfocusingdistanceof0.17m(6.7inches).

Figure31 OpticalsystemofthenewRF35mmF1.8MACROISSTMlens

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The lens has the new control ring—with 54 clicks per revolution. It has a high performing opticalimagestabilizationsystemwithshake-correctionallowinghand-holdingatshutterspeedsupto5-Stopsslowerthanwouldnormallybepossible—impressiveforalenshavingabrightnessofF1.8.

In twokey areas anotable improvementwas implemented in this new35mm lens compared to thewell-knownEF35mmf/2ISUSMlens.Theoveralllengthofthelens’sopticalpathisshortenedfrom105mm to80.5mmand the all—important operational optical speedof the lens is nowF1.8. Figure 32showsEF35mmf/2ISUSMontheleftcomparedtothenewlensontheright.

Figure32 New RF35mm F1.8MACRO IS STM lens (on the right) having a large diameter rearelementhelpsoptimizetheoverallimageperformanceprojectedontothefullframeimagesensor

Acomparativeinspectionofthesetwolensesquicklyrevealsaquiteradicalchangetotheoverallopticalassembly. NotethelargefinallenselementoftheRF35mmF1.8MACROISSTMcomparedtothatoftheEFlens.Ofspecialinterestarethesmallerfrontelementsinthenewlens—whichstillachievesthefasterF1.8maximumaperturebecauseofthe largediameter iristhat ispositionedunusuallynearthefrontofthe lens. Theentirefrontsection ismovedtofocusthis latest35mmlens. But, it ismuchsmaller-diameter and lighter in weight, making it possible to switch from a ring-type USM to thesteppingmotor(STM)focusdrivesystem.Amongotherbenefits,thischangetoSTMfocusdrivemeansmuchsmootherfocusperformancewhenthelens-camerasystemisusedforvideoshooting.

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Figure33MTFcurvesforRF35mmF1.8MACROISSTMlens

Figure34MTFcharacteristicsofthenewRF35mmF1.8MACROISSTMlenscomparedtotwo35mmEFlenses

The new RF35mm F1.8 MACRO IS STM has remarkably similar MTF characteristics to those of theexcellentEF35mmf/1.4Llens.Butitisamorecompactandlightweightlensandhasamacroshootingcapabilityatf/1.8brightnessthatcannotbematchedbyanyEFlens.ThecontrolalgorithmofthenewopticalISaugmentstheDualSensingISoftheEOSRlens-camerasystem,providinghighimagestabilityinmacrophotographyusingupto5stopsshutterspeed.

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1. 10Lp/mmSagittalforthenewRF35mmF1.8MACROISSTMlensmaintainsaslightlyhigherMTFacrossthetotalimageheightcomparedtotheEF35mmf/2ISUSMandismuchlowerthanthatoftheEF35mmf/1.4LIIUSM

2. 10Lp/mmMeridionalexhibitsalowerMTFthanbothEF35mmlenses

3. 30Lp/mmSagittalfortheRF35mmF1.8MACROISSTMissomewhatsimilartothatoftheEF35mmf/2ISUSMoutto15mmheightbutslightlyhigheratmaximumimageheightbutisnotaswellcontrolledastheEF35mmf/1.4LIIUSM

4. 30Lp/mmMeridionalcurveforRF35mmF1.8MACROISSTMlensisnotashighasthatoftheEF35mmf/1.4LIIUSMandissomewhatsimilartothatoftheEF35mmf/2ISUSM

12.0EFLENSMOUNTADAPTERSTheintentoftheEOSRsystemistobuilduponthehighlysuccessfulCanonEOSsystemandtakeittonew levels of performance and operational flexibilities for both digital still and motion imaging.CentraltothestrategyistheMountCoreDesign—thenewRFmount.FoldingtheexistingworldofEFlenses(includingEF-Slenses)intothisexpandingimaginguniverseisapivotalpartoftheoverallplan.Todothisthreespecialadaptershavebeendeveloped:

1. MountAdapterEF-EOSRDirectmechanicalandelectricalcouplingbetweentheEF lensandany thenewEOSRcameraandanyfutureEOSRcameras

2. ControlRingMountAdapterEF-EOSRAnadapterforexistingandfutureEFlensesthatincorporatesthesameinnovativenewringforcontrolofexposurethatisfoundonRFlenses.Whentheringisrotatedabuilt-in sensor andmicroprocessor detect andprocess thatmotionwhich is transmitted tothecameraviathecontacts

3. Drop-InFilterMountAdapterEF-EOSRAmountadapterforEFlenses,withdedicateddrop-infilterslot.ItallowsadditionofaCanonDrop-InCircularPolarizingFilterA(withfullrotationcapabilitiesintheadapter),oraCanonDrop-InVariableNDFilterAwithrangeof1.5–9stops.AnavailableDrop-InClearFilterAshouldbeusedwheneverthetwospecializedfiltersarenotin-place.

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12.1MountAdapterEF-EOSR

Figure35 MountAdapterEF-EOSRthatadaptsEFlensestothenewRFmount

12.2ControlRingMountAdapterEF-EOSR

Figure36 ControlRingMountAdapterEF-EOSRthatincorporatesthecontrolring

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12.3 Drop-InFilterMountAdapterEF-EOSR

Figure37Drop-InFilterMountAdapterEF-EOSRshowingthevariousoptionsforthedrop-inopticalfilters

13.0EOSRLENS-CAMERASYSTEM

TheEOSRsystemincorporatesavarietyofoperationalempowermentsthathavebeenmadepossiblebecause of new innovation in the new lens series and the high-speed electronic communicationbetweenthelensandthecamera.

13.1EnhancedImageStabilizationSystemHighpicturesharpnessisensuredaslongaseachpointoftheimageremainspreciselypositionedontheimager sensor. Lens-camera shake is a significant cause of blurred images. Minute deflections andtremorstothelens-cameramomentarilyshiftstheprojectedimagearoundtheimagersensorplane—causinginadvertentimageunsteadinessinthedisplayedimage,withanassociatedblurringandlossofpicture sharpness. These lens-camera disturbances include jolting associated with handheld andshoulder mounting by a camera operator who is in motion, vibrations when tripod mounted on anunstable platform or in windblown environments, to the higher vibration frequencies encounteredwhenoperatingonvehicles,boats,andaircraft.

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InthenewEOSRsystemthelensembodiesnewtechnologiesthatcombinewiththeISsysteminthecameratoimplementanaugmentedcontrolovertheimageblurringthatcanbecausedbyshakingandvibration of the lens-camera system. This is empowered by an interactive data communicationbetween the two. Within the lens a dual gyro sensor system detects any inadvertent physicalmovementsofthesystemandthisdataisreportedacrosslens-cameracommunicationtotheDIGIC8processor. At the same time the image sensor is “seeing” any blur stimulated by these samemovementsand italsoreports this imagedatatotheDIGIC8processor. Thesetwodatareportsarealgorithmicallyprocessedatveryhighspeedandacompensationcontrolsignal isgeneratedandsentbackathighspeedtothelenstoactuatetheISopticalelementthatcounteractsthedisturbance.

Figure38 The lens gyro sensor reports lens movements and the image sensor reportsassociatedblurdatatotheDIGIC8processor

DuringvideorecordingthereistheaddedabilitytocombineanyopticalImageStabilizationinthelenswithelectronicImageStabilizationwithintheCMOSimagesensor.CombinationISaddsfiveaxisdegreeofcontrolelectronicISattheimagesensorasshowninFigure38,inadditiontotheup/down,left/rightstabilizationtypicallycarriedoutinthelens. ThelensISsystemexercisescorrectionintheYaw,Pitch,andRolldirections—seeFigure39. The in-camera stabilizationsystemexercisesadditional controloverYawandPitch—aswellascorrectioninRollandtheverticalandhorizontalplanes.

Figure39 ShowingthefivedimensionsofimagestabilizationcorrectionintheEOSRcamera

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13.2 DigitalLensOptimizer(DLO)SystemTheDigital LensOptimizingsystem isbuilt into theEOSRcameraand is intended to implement real-timecorrectionsforanumberofopticalaberrationsanddistortionsencounteredoverawiderangeofshootingconditions. BeforethelightraysreachtheCMOSimagesensortheypassthroughthemulti-elementlensandvariousfiltersasillustratedinFigure40.

Figure40 Asimplisticrenditionofthepathofthe lightraythatenterthe lensandareultimatelyprojectedontothecameraimagesensor

A point light source that travels through a lens system encounters numerous aberrations — bothmonochromaticandchromatic—thattendstospreadthatlight.TheopticalscientistsspeakofaPointSpreadFunction.However,thecumulativeeffectoftheaberrationsistocreatearangeofshapesinthatspreadfunctionandtheyareaffectedbytheimageheightandbytheoperationalsettingsofzoom,focus,andiris.

Therearetwobasiclimitationstoimageresolutionwithinalllenses—thefirstisthecumulativeeffectof the six monochromatic and chromatic aberrations (termed the defocusing distortions and whichworsenasthelensapertureapproachesmaximum),andthesecondisdiffraction(whichworsensasthelensapertureisstoppeddown)—seeFigure41.

Figure41 Cumulative optical aberrations place limits on lens resolution near wide aperturesettingsanddiffractionplacesotherlimitsasthelensapertureisstoppeddown

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Figure42Showingthestoreddatafilesonlensaberrationsandthereal-timelensoperationalcontrolscommunicationacrosstotheDLOenginewithintheEOSRcamera

TheDLOsystemcanimplementcorrectionsforthefollowing

1. Resolutionlossduetocumulativeaberrations

2. Resolutionlossduetodiffraction

3. Lateralchromaticaberration

TheDigitalLensOptimizerisparticularlyusefulwhenusinglensesthatarepronetoopticaldistortionorblur,oftenprovidingsubstantialimprovementsinimagequality.

Inphotographiccircles,manywillstopdownslightlyfrommaximumaperturewhentakingphotoswithashallowdepthof field forablurryeffect,or for scenes requiringa fast shutter speed.This isdone topreventadegradationofresolutioninthefocalarea. WhenDigitalLensOptimizerisused,highimagesharpnesswithminimal aberrations canbeachievedevenwithmaximumaperture. Whetherusingafast shutter speed to capture a special moment, or a shallow depth of field for a blurry effect, thedesired aperture canbe chosen freely.Awider aperture also allows lowering the ISO speed for evenbetterimagequality.

Usinga greatdepthof field forpan focus isoneof the standard techniquesofphotography.But thisinvolvesatradeoff,becausesmallaperturescouldnotbeusedifsofteningoftheimagecausedbythediffractioneffectwastobeavoided.WiththeDigitalLensOptimizer,theentirerange,fromfullyopentominimumaperture,canbeused,givingfreereigntocreativity.EvenatmiddlerangeF-stops,whereimagequality is generally good, aberrations anddiffractionused to reduce imagequality to a certainextent.Shutterspeedcanbeatwill,regardlessofaperturestop.

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IntheEOSRsystem,DigitalLensOptimizercanbeappliedin-camerawhentheRAWfilesareconvertedto JPEG image files, andusers canexpect improvements in finedetail and resolution, especiallywithsubjectshavinglotsofinherentdetail(thinkgrassandfoliageinlandscapes,texturesinfashionfabrics,etc.). IfRAWimagesarerecordedandthenprocessedinCanon’sDigitalPhotoProfessionalsoftware,similarbenefitscanbeappliedinprocessingtheimages.

13.3DualPixelCMOSAF

EOS R system embodies a powerful auto focus systemwhere the sensing of sharp focus takes placewithin the image sensorphotosite itself. Itmobilizes thedualphotodiodeswithineachphotosite tocreate two separate images that facilitates a phase detection system that indicates the degree ofdefocusing.

Figure43 ShowingthedualphotodiodestructureofasinglephotositeintheCMOSimagesensorusedintheEOSRcamera

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Figure44 Showing the separate processing of the dual pixel data from the image sensor— forvideoandforAutoFocus—attheentrystageoftheDigic8processor

Figure44illustratesthemannerinwhichthesetsofdualpixeloutputsfromtheCMOSimagesensoraresenttotheDIGIC8processingmicrocircuitthatwasdevelopedbyCanon.Withinthisprocessor,thesestreams are separately fed to the primary RGB video processing system (where the two photodiodesignalsaresummed)andtoadataprocessingsystemthatanalyzesthephasedifferencebetweenthetwoandmakesallofthedecision-makinganddataprocessingassociatedwiththeAutoFocussystem.While all of themillions of photosites aredelivering the “dual pixel” data, theoperational aspects ofAutoFocusdictatethatonlyaselectnumberoftheseareactivatedatanygiventime.Thisisbecausethecameraoperator(or forthecamera,whenAFmethods likeFaceDetect+Trackingareactive)willmake thedecisiononwhichparticular subjectwithin theoverall picture frame is chosen for sharpestfocus.Consequently,acursortypesystemmustbeimplementedtofacilitatethischoice.ExperiencesgainedintheearlygenerationsofDualPixelCMOSAFsystemsproducedthefollowing:

1.Broadrequesttoprovidespatialmovementofthesamplingarea—sothatdifferentsubjectswithinagivenscenecanbeselectedforsharpestfocus

2.Rangingperformanceimprovementisneededinlowsceneilluminationsituations

3.ImprovementinaccuracyofthesystemasISOsettingincreased

4.Autofocusshouldideallybearealtimeaction(orascloseaspossibletorealtime)sospeedofcalculationsshouldbeincreased

5.Improvementinthecalculatingalgorithmtoelevatereliability

AmoredensesamplinglatticeofphotositesforthecursorwasdevelopedtoincreasesensingsensitivityandaccuracyoverawiderrangeofsceneilluminationandcameraISOsettings.ThecursorsizecanbeadjustedtoaccommodatethespecificAFneedsofagivensceneandsituation.

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Itcanrangeacrosstheimageplaneaccordingtothediscretemanually“SelectableAFPoints”outlinedinFigure 45. There are 87 positions horizontally (covering 88% of the image width) and 65 positionsvertically(covering100%oftheimageheight)fortheseselectableAFpoints.Thisensuresverypreciseautofocusoperation.

Figure45 Showingthedispositionofthediscretelocationswhichismanuallyselectable

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13.4 ComparisonofEOSRLens-CameraSystemwithEFLensandDSLR

AsenseofthesignificantcompactnessthattheEOSRcamerasystemcanofferisshownintheoutlinedrawingofFigure46whichcomparesittotheCanonEOS5DMarkIV.

Figure46 OutlinedrawingofanewEOSRcamerasystem(lower)comparedtoanequivalentCanonEOS5DMarkIVcamera(upper)

TheEOSRsystemhasaflangefocaldistanceofjust20mm,adistancethatwascarefullyoptimizedtosupporttheoptimalopticalconditionsprovidedbyashortbackfocaldistanceandthemechanicalrigidityneededtoreliablysupportaheavylens.

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AmoredramaticillustrationisshowninFigure47—whicheffectivelyconveyshowthenewlensandmounthaveveryeffectivelyshortenedtheoveralllengthofthelens-camerasystem.

Figure47 ShowingtheRF24-105mmF4LISUSMlensmountedtothefirstEOSRcamera(rightsideofpicture)sidebysidewithanequivalentEFlensonaCanonEOS5DMarkIVcamera(leftside)

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14.0SUMMARY

TheEOSsystemishugelyestablishedacrosstheglobeandcontinuestomoveinnewdirections—asthelines between still andmotion imaging blur and as lens-camera image quality steadily increaseswitheverygeneration.Applicationsofstillandmotionimaginghaveseenextraordinaryadvancesatalllevels—fromamateurallthewaytothehighestprofessionals.Collectively,aestheticaspirationsandcreativeingenuitiesoftheendusersareescalating—andthebarcontinuestobeelevatedinrequirementsforbothimagequalityandoperationalfreedoms.

TherecognitionthatallthatisbestabouttheEOSsystemmustbesupportedintothefutureistemperedbyanacknowledgementthatnewdesignoptionsneededtobeopened. ThenewEOSRsystemwasspawnedby the vast accumulationof EOS systemexperiencesover thepastdecades, by acceleratingtechnological advances in optics, image sensors anddigital imageprocessingovermore recent years,andbyagrowingrecognitionthatongoingenhancementstothesystemwouldrequiremoredegreesofdesignfreedomforlensesandcameras.

AlongexaminationbyCanonR&DandLensDevelopmentgroups—onboththeopticalandcameraside— concluded that opticswas central to a new future strategy. In the context of the digital camera,Moore’sLawremainsamazinglyresilientfromitsfirstpromulgationattheendofthe1970’s—thereasyet seems no end in sight. As a consequence, digital camera processing has benefited to anextraordinary level — as testified by the huge range available today, their continuing performanceelevations,andtheirsteadilydecreasingsizeandweight.Itmustbeanticipatedthiswillcontinue.

Lenses, on theotherhand, enjoynoequivalent technological stimulant. The sciencesofoptics andoptomechanics advance methodically. Yet, the dictates of higher optical performance, greaterflexibilitiesinoperationalspecifications,andtheintractableconstraintsofsizeandweightoflensesarepivotal to supporting future prospects in imaging. EOS R systemwas born on the basis of decisivelyremovingsomeconstraintsonlensdesigns.

CentraltothenewEOSRsystemstrategywastherecognitionthatthelarge54mmdiameteroftheEOSsystemwouldcontinuetopayopticaldividendsfarintothefuture.Butthe44mmflangebackdistancehad surfaced as a constraint whose time had come to be dealt with. Significantly shortening thisdistancewouldyieldimmediatenewdegreesoffreedominopticaldesign.Butthis,ofnecessity,wouldhavetobebalancedwithrigidityofthenewmount,easeofattachinganddetachinglenses,durability,dust and drip resistance. In-depth design reviews within Canon yielded the new RF lensmount—preserving the54mm innerdiameterwhile significantly shortening the flangeback to20mm. Now,positioningof largediameter lenselementsmuchclosertothe imagesensor(especiallythefullframesensor)wouldsupportanimportantenhancementofimagequality.

ThispaperhasdiscusseddetailsofthenewRFlensmount.TheadvantagesofthisnewmountdesignareimmediatelyevidentinthedesignsofthefirstfourlensesoftheRFlensfamily—asoutlinedinthispaper.

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