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Canon RF 100–400mm F5.6–8 IS USM vs Canon RF 45mm F1.2 STM

Every spec side by side, from each maker's published figures.

Better figure, where one is clearly better

CanonRF 100–400mm F5.6–8 IS USMCanonRF 45mm F1.2 STM
Overview
ReleasedOctober 2021November 2025
Optics
Lens typeZoomPrime
Focal length100–400 mm45 mm
Maximum aperturef/5.6–8f/1.2
Minimum aperturef/32–45f/16
Optical construction12 elements in nine groupsNine elements in seven groups
Special elementsOne UD element and one PMo aspherical elementOne plastic-moulded aspherical element (Canon USA)
CoatingsSuper Spectra; no fluorine coating, per UK maker tableSuper Spectra coating
Aperture detail–f/1.2–16
DiaphragmNine bladesNine aperture blades
Angle of view–43°35′ horizontal, 29°50′ vertical and 51°20′ diagonal on full frame
Mount and compatibility
MountsCanon RFCanon RF
Image circleFull frameFull frame
CompatibilityCanon RF mount, full-frame image circle; incompatible with EF DSLRs and EOS M camerasCanon EOS R cameras; full-frame image circle
Teleconverter supportRF1.4× gives 140–560 mm f/8–11 and maximum 0.58×; RF2× gives 200–800 mm f/11–16 and maximum 0.83×. Maker confirms autofocus and IS, with reduced AF coverage on listed EOS R bodies; extenders usable throughout the zoom rangeCanon RF extenders not compatible
Focus and stabilisation
AutofocusYesYes
Minimum focus distance0.88 m0.45 m
Maximum magnification0.41×0.13×
Optical stabilisationYesNo
Autofocus detailNano USM autofocus and electronic manual focusGear-type STM autofocus with magnetic focus-position detection; full-time electronic manual focus
Focus distance detailMaker minimum focus 1.2 m at 100 mm, 0.88 m at 200 mm, 0.95 m at 300 mm and 1.05 m at 400 mm. Main value is the closest published distance at 200 mm; Cameralabs’ approximate constant-distance observation does not replace the maker’s per-focal-length tableMinimum focusing distance 0.45 m; Canon does not separately specify AF/MF distances
Magnification detail0.09× at 100 mm, 0.24× at 200 mm, 0.34× at 300 mm and 0.41× at 400 mm; no unpublished AF/MF distinction inferred–
Stabilisation detailOptical IS rated 5.5 stops at 400 mm on EOS R under CIPA, yaw/pitch; coordinated EOS R5 body/lens IS rated six stops under the same maker conditions. Cameralabs measured approximately five stops at 100 mm and three at 400 mm with EOS R6, a different test conditionNo optical image stabilisation (Canon USA)
Video featuresCameralabs found little focus breathing and mostly maintained focus while zooming in its tests; these are reviewer observations rather than maker parfocal certification–
Design
Dust and moisture resistantNoNo
Filter diameter67 mm67 mm
Maximum diameter79.5 mm78 mm
Length164.7 mm75 mm
Weight635 g346 g
ControlsSeparate zoom, electronic manual focus and custom control rings; AF/MF and IS switches; zoom lockSeparate focus and clickable control rings; AF/MF switch; no iris ring or lens function button (Canon USA)
Filter detail–67 mm front screw-in filter thread
Zoom designExtending zoom barrel; main maker length measured retracted–
Weather resistanceUK maker specification explicitly states no dust/moisture resistanceNo dust or weather resistant construction (Canon USA)
Dimensions detailApproximately 79.5 mm maximum diameter × 164.7 mm length when retractedApproximately 78 mm maximum diameter × 75 mm length
Weight detailApproximately 635 g lensApproximately 346 g lens
Lens hoodET-74B, optional accessoryOptional ES-73B hood and LP1116 case; E-67 II front cap and Lens Dust Cap RF listed by Canon
In the box–Front and rear lens caps (Amateur Photographer); hood not included
Release detailOctober 2021 marketed month in Canon Camera Museum, matching Canon Canada’s original October availability. No exact worldwide first-sale day inferred; no direct replacement of brighter EF or RF L-series zooms assumedCanon Japan's 14 November 2025 notice confirms first sale on 28 November 2025; Photography Blog instead reports availability from 20 November without a matching regional maker day, so no UK date is inferred

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