Canon EOS-1D C Brochure (en)

center of the lens do not converge at the same 
point as light rays coming through the lens 
edge, the image can appear blurred because 
there is no sharp point of focus. Canon’s 
aspherical elements use a varying curved  
surface to help ensure that the entire image 
plane appears focused. Aspherical optics 
also help to correct curvilinear distortion as 
one might find in ultra wide-angle lenses. 
Canon designs aspherical elements with 
extremely precise variable curvature of one 
or both sides, making possible lighter, more 
compact lenses.
Subwavelength and Fluorine  
Anti-smear Coatings
The Subwavelength Coating (SWC) is a  
proprietary lens coating that helps control 
ghosting and flare to a far greater degree  
than with earlier coating technologies.  
Utilizing SWC technology on large-curvature 
lens elements that are mainly found in  
wide-angle lenses significantly minimizes  
the occurrence of ghosting and flare caused  
by reflected light in environments that have 
posed problems. SWC is used on the Canon 
wide-angle lens, EF 24mm f/1.4L II USM.  
The fluorine anti-smear coating helps  
minimize soiling, smears and fingerprints  
for easy cleaning.
Air Sphere Coating (ASC) technology is designed 
to help reduce backlit flare and ghosting  
significantly typical with multi-optic zoom lenses. 
ASC includes air spheres that are applied over the 
lenses’ conventional vapor deposition coatings.
Focus Preset
Focus Preset enables you to program a focusing  
distance in the camera’s memory. Normal 
picture taking and focusing are unaffected 
by preset distances. For example, at a soccer 
game, you Focus Preset the goal area.  
Shoot normally elsewhere on the field, but 
once the action moves toward the goal, the 
user can instantly return to the preset  
distance by turning a ring on the lens.
Ultrasonic Motor lenses. 
Ring-type USM lenses, 
found in large aperture 
and super-telephoto 
designs, permit manual 
focusing  wit        hout  first 
switching out of the 
auto mode. Micro USM 
designs bring the 
performance benefits of 
Canon’s USM technology 
to a wide assortment of affordable EF lenses. 
L-Series Lenses
Highly regarded among professional  
photographers, Canon L-series lenses are  
distinguished by a bold red ring around the 
outer barrel. What makes them truly distinctive, 
however, is their remarkable optical  
performance – the result of sophisticated 
Canon technologies, such as Ultra-low  
Dispersion (UD) glass, fluorite and aspherical 
elements and Super Spectra Coating.
Fluorite / UD Elements
Reducing color fringing, or chromatic aberration, 
has been one of the great challenges in the 
design of telephoto lenses. L-series telephoto 
lenses – like the EF 70–200mm f/2.8 IS II USM 
and EF 300mm f/4L IS USM – employ Canon’s 
Ultra-low Dispersion glass to help minimize 
this effect, providing much improved contrast 
and sharpness. Even more effective at  
suppressing chromatic aberration are fluorite 
elements, used in high-end super-telephoto 
L-series lenses. Composed of crystallized 
calcium fluoride (CaF
), a single fluorite element, 
although costly, has roughly the corrective 
power of two UD glass elements, giving these 
L-series lenses their spectacular performance 
and relatively compact design. 
Aspherical Elements
Wide-angle lenses and fast normal-focal-length 
lenses often suffer from spherical aberration. 
When the light rays coming through the 
the EF-S 18–135mm f/3.5–5.6 IS STM uses a  
lead-screw type, which prioritizes AF performance, 
offering smooth and quiet operation.
Diffractive Optics
Canon’s use of diffractive optics (DO) results 
in high-performance lenses that are much 
smaller and lighter than traditional designs. 
Canon’s multilayer diffractive elements are 
constructed by bonding diffractive coatings 
to the surfaces of two or more lens elements. 
These elements are then combined to form a 
single multilayer DO element. Conventional 
glass lens elements disperse incoming light, 
causing chromatic aberration. The DO element’s 
dispersion characteristics are designed to 
help reduce chromatic aberrations significantly 
at various wavelengths when combined with 
conventional glass optics. This technology 
results in smaller lenses that provide amazing 
results. Canon has also developed a triple-layer 
type DO lens that uses an advanced diffractive 
grating to deliver excellent performance,  
with superb control of color fringing. This 
configuration is ideal for zoom lens optics and 
provides significant reductions in size. A good 
example is the EF 70–300mm f/4.5–5.6 DO IS 
USM lens, which is 28 percent shorter than 
the EF 70–300mm f/4–5.6 IS USM lens.
Ultrasonic Motor
Canon developed the world’s first lens-based 
Ultrasonic Motor (USM) to power the lens 
autofocus mechanism. Instead of large noisy 
drive trains powered by conventional motors, 
Canon USM lenses employ the minute electronic 
vibrations created by piezoelectric ceramic 
elements. The focusing action of the lens is fast 
and quiet, with virtually instantaneous stops 
and starts. USM lenses also draw minimal 
power from the camera, helping ensure longer 
battery life. Canon makes two types of  
Ring-type USM
Micro USM
Convergence of parallel light 
rays by an Aspherical lens.
Spherical aberration  
of spherical lens.
Optical Image Stabilizer Mode 2  
and Mode 3 
The standard settings of the Optical Image 
Stabilizer are set so that it is most effective 
when photographing stationary subjects. 
However, when panning with a moving subject is 
attempted (tracking of the subject horizontally 
or vertically), the shake-correction of the OIS 
may inadvertently over-compensate and 
interfere with framing. To help resolve this, 
Canon developed Optical Image Stabilizer 
Mode 2. In this mode, if you move the lens to 
follow a subject for a pre-determined time, the 
Optical Image Stabilizer does not correct for the 
intentional panning, while continuing to correct 
any camera shake that’s perpendicular to the 
panning motion. The result is a virtually smooth 
viewfinder image as you follow the moving 
subject. Optical Image Stabilizer Mode 3 
activates IS only when the shutter button is 
fully pressed, allowing for easy panning of 
fast-moving subjects. 
Dynamic Image Stabilizer 
During video shooting, Canon’s Dynamic IS 
stabilization offers a wide image stabilization 
correction range, creating an Image Stabilizer 
effect equivalent to a shutter speed approximately 
4 settings faster, effective for shooting  
handheld, while walking, and in similar types 
of shooting situations.
A challenge of shooting DSLR video has been 
achieving continuous autofocus. In response, 
certain Canon EF and EF-S lenses now offer a 
stepping motor (STM) drive, designed to deliver 
smooth and quiet continuous AF during video 
shooting when paired with the Movie Servo AF 
feature found on select EOS cameras. Canon’s 
decades of optical experience allows Canon to 
incorporate the right type of stepping motor for 
each lens. The EF 40mm f/2.8 STM utilizes a 
gear-type that allows the lens to achieve an 
ultra-compact and lightweight design; whereas 
Comparison of optical characteristics between  
optical glass and Fluorite
Taken with EF 100–400mm f/4.5–5.6L IS USM
Chromatic aberration canceled out
Chromatic aberrations reversed from 
that of a refractive optical element
Image formation in the red, green and 
blue wavelength order
Multi-Layer Diffractive 
Optical Element
Refractive Optical Element 
and Multi-Layer Diffractive 
Optical Element Combined
Refractive Optical Element
Image formation in the blue, green 
and red wavelength order
Chromatic aberrations
Correction of Chromatic Aberration by the Multi-Layer 
Diffractive Optical Element
1: Horizontal Camera Movement
2: Vertical Camera Movement
Camera Movement
(Image Stabilization stopped)
Camera Movement
(Image Stabilization stopped)
Image Stabilization
Image Stabilization
Optical Image Stabilizer Mode 2 Stabilization Control