Canon RF 10-20mm F4 L IS STM User manual

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Instructions

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Thank you for purchasing a Canon product.
Canon RF10-20mm F4 L IS STM is a ultra-wide
zoom lens for use with EOS R series cameras.
z“IS” stands for Image Stabilizer.
z“STM” stands for Stepping Motor.
Conventions used in these instructions
Warning to prevent lens or camera malfunction
or damage.
Supplementary notes on using the lens and
taking pictures.
Camera Firmware and Camera
Applications
Please use the latest versions of firmware and
applications with the camera in use. For details on
whether the firmware and applications in use are the
latest version or not, and for details on updating them,
please check the Canon website.
If the camera’s* firmware is not a compatible
version, the following limitations will apply.
zMagnified view functionality is not available.
zIn some cases, the camera malfunction may
occur.
* Applies to the following camera models:
EOS R and EOS RP

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Precautions to ensure that the camera is used
safely. Read these precautions thoroughly. Make
sure all details are observed in order to prevent
risks and injury to the user and other people.
Warning
Details pertaining to risks that may
result in death or serious injury.
zDo not look directly at the sun or other strong
light sources through a lens. This may result in
loss of sight.
zDo not leave a lens in the sun without the lens
cap attached. The lens may concentrate entering
sunlight and cause a malfunction or fire.
Caution
Details pertaining to risks that may
result in injury or damage to other
objects.
zDo not leave the product in places exposed to
extremely high or low temperatures. The product
may cause burns or injury when touched.
Safety Precautions

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Handling Precautions
zDo not leave the product in excessive heat such as
in a car in direct sunlight. High temperatures can
cause the product to malfunction.
zIf the lens is taken from a cold environment into a
warm one, condensation may develop on the lens
surface and internal parts. To prevent condensation
in this case, first put the lens into an airtight
plastic bag before taking it from a cold to warm
environment. Then take out the lens after it has
warmed gradually. Do the same when taking the
lens from a warm environment into a cold one.
zIn order to optimize aperture control, there are
occasions in which the aperture blades will move
during zooming and focusing, even when the
aperture value is set for aperture-priority AE or
manual exposure, etc.
zPlease also read any lens related handling
precautions listed in your camera’s instruction
manual
.
Shooting Precautions
zT
his lens has a short focus distance, which means dirt
or dust on the surface of the front lens will show up
easily on photos. Use a commercially-available blower
to remove dirt or dust from the front lens surface.
General Precautions
zT
his lens has a wide shooting angle, meaning
sunlight or other strong light sources can enter
the image easily. This can lead to flares or ghosts
under some shooting conditions. To prevent this, we
recommend being aware of where the light source is,
such as photographing from shadows or other places
where a strong light source will not enter the lens.
Video Shooting Precautions
zThe lens is compatible with focus breathing
correction* when shooting video.
*
This refers to a function to correct for and reduce
changes in view angle that occur when focus changes.
zP
lease refer to the Canon website or the camera’s User
Manual to check if your camera allows focus breathing
correction, how to set it, and points to note about it.
zThis lens covers an ultra-wide angle, so in some
circumstances there may be image distortions or
slight movement around the sides of the frame
when focusing using focus breathing correction.
In that event, it might be reduced by the following:
• Change the focal length of the lens you are
using to telephoto.
• Reduce the focus speed. (Slow the AF speed for
Movie Servo AF.)
• Increase the f-stop. (It does not reduce the slight
movements around the edge of the frame.)

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This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions: (1) This
device may not cause harmful interference, and (2) this
device must accept any interference received, including
interference that may cause undesired operation.
Do not make any changes or modifications to the equipment
unless otherwise specified in the instructions. If such
changes or modifications should be made, you could be
required to stop operation of the equipment.
This equipment has been tested and found to comply with
the limits for a class B digital device, pursuant to part 15
of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference in a
residential installation. This equipment generates, uses and
can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful
interference to radio communications.
However, there is no guarantee that interference will not
occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception,
which can be determined by turning the equipment off and
on, the user is encouraged to try to correct the interference
by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and
receiver.
• Connect the equipment into an outlet on a circuit different
from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician
for help.
CAN ICES-3 (B) / NMB-3 (B)

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Focusing ring (→ 7)
Control ring (→ 8)
Image stabilizer switch (→ 10)
Lens function button (→ 9)
Zoom ring (→ 8)
Focus mode switch (→ 7)
Rubber ring (→ 6)
Contacts (→ 6)
Lens mount (→ 6)
Zoom position index (→ 8)
Lens mount index (→ 6)
Built-in lens hood (→ 12)
Gelatin filter holder (→ 13)
z For detailed information, reference page numbers are provided in parentheses (→ **).
Nomenclature

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Lens mount index
Lens release button Dust cap
Attaching the Lens
Align the lens mount indexes of the lens and
camera, and turn the lens clockwise until you
hear a click.
Detaching the Lens
Turn the lens counterclockwise while pressing
the camera’s lens release button. Detach the
lens once it has stopped turning.
Please refer to the camera’s instructions for
details.
zSet the camera’s power switch to OFF when
attaching or detaching the lens.
zAttach the lens cap before detaching the lens
from the camera.
zAfter detaching the lens, place the lens with the
rear end up and attach the dust cap to prevent
the lens surface and contacts from getting
scratched. Make sure the lens and dust cap
mount indexes are aligned when attaching the
dust cap.
zContacts that are scratched, soiled, or have
fingerprints on them may result in faulty
connections or corrosion, which may lead to
malfunctions. If the contacts get soiled, clean
them with a soft cloth.
zThe lens mount has a rubber ring to improve
dust-resistance and water-resistance
performance. This rubber ring may cause
friction marks to appear around the camera’s
lens mount, although this will have no effect on
usage.
zRubber rings can be replaced at Canon Service
Center. (chargeable)
1. Attaching and Detaching the Lens

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Focus mode switch
Focusing ring
To shoot in autofocus (AF) mode, set the focus
mode switch to AF.
To use only manual focusing (MF), set the focus
mode switch to MF, and focus by turning the
focusing ring.
2. Setting the Focus Mode
zQuickly turning the focusing ring may result in
delayed focus.
zThe lens’ focusing ring is electronic.
zIt is possible to set cameras that support
electronic fulltime manual focusing to manual
focusing when the camera is in the operational
mode. However, the camera settings need to be
changed.
zWhen AF operation is set to One-Shot AF,
manual focus is possible after autofocusing
has been completed by continuing to press the
shutter button halfway (electronic manual focus
function). However, the camera settings need to
be changed.
zWhen movie recording, the AF speed will be
slower than the still photo shooting mode. It is
possible to adjust the AF speed on the camera
by setting Movie Servo AF to [Enable].
Please refer to the camera’s instructions for
details.

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3. Zooming
To zoom, turn the lens’ zoom ring.
zBe sure to finish zooming before focusing.
Zooming after focusing can affect the focus.
zBlurring may temporarily occur if the zoom ring is
quickly turned.
The control ring can be assigned the functions
that are commonly used with cameras, such as
shutter speed and aperture settings.
Control ring
The click action of the control ring allows you to
have a sense of how much it is being turned.
Please refer to the camera’s instructions for
details on how to use the control ring.
zThere are cases in which the sound of control
ring operations may be recorded when shooting
movies.
zThe clicking sensation of the control ring can
be removed by the Canon Service Center.
(chargeable)
4. Control Ring

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5. Lens Function Button (AF Stop Button)
In the default settings, the lens function button
serves as a AF stop button. You can assign
different functions to the button from the
[Customize buttons] section of the camera.
Please refer to the camera’s instructions for
details.
Lens function button
(AF stop button)
Use as a AF stop button
During autofocus operation, you can press an AF
stop button to temporarily pause autofocus, and
then release the button to resume.
Press an AF stop button to maintain a focusing
distance or to avoid focus search.
Press the shutter button while holding down an
AF stop button to shoot at that focusing distance.
zUseful when autofocus is operating mostly in
Servo AF.

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6. Image Stabilizer
Set the image stabilizer switch to ON when you
want to use the Image Stabilizer.
zThis function provides image stabilization
appropriate for shooting conditions (such as
shooting still subjects and panning shots).
zThe coordinated control will work in
combination with cameras with in-body Image
Stabilizer.
zSupports peripheral control** using coordinated
control with the camera*.
zSet the image stabilizer switch to OFF when
you are not going to use the Image Stabilizer.
zThe Image Stabilizer cannot compensate for a
blurred shot caused by a subject that moved.
zThe Image Stabilizer may not be fully effective if
you shoot from a violently shaking vehicle or other
transportation.
zWhen using a tripod, the Image Stabilizer might
not be fully effective or it might be better to set the
image stabilizer switch to OFF, depending on the
type of tripod and where the tripod is located, as
well as on the camera’s settings such as shutter
speed.
zEven with a monopod, the Image Stabilizer will
be as effective as during hand-held shooting.
However, depending on the shooting conditions,
there are cases in which the Image Stabilizer
effect may be less effective.
* Please use the latest version of firmware with the
camera.
For supported cameras, details on whether the firmware
is the latest version, and how to update, please check
the Canon website.
**In addition to normal control, this reduced changes of
the distortion around the screen periphery that often
happen due to shaking with wide-angle lenses.

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Image Stabilizer
The Image Stabilizer for this lens is suited to hand-held shots in the following conditions.
zIn semi-darkened areas such as indoors or
outdoors at night.
zIn locations where the flash cannot be used,
such as art museums and theater stages.
zIn situations where your footing is uncertain.
zIn situations where fast shutter speed settings
cannot be used.
zPanning shots of vehicles, trains, etc.
It compensates for vertical camera shake during panning shots in a
horizontal direction, and compensates for horizontal camera shake
during panning shots in a vertical direction.

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7. Lens Cap
Lock knobs
The lens cap can be attached by pinching the
lock knobs and vertically aligning the lens cap
with the built-in lens hood as shown in the
diagram.
zThe recessed sections of the lens hood that the
cap locks on to are located at the front inside
edge of the top and bottom petals.

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8. Filters (Sold separately)
This lens has a gelatin filter holder at the rear.
Download the filter template files, print them out, then lay the filter over the template and cut to
match. Then insert the filter in the holder.
1Cut the gelatin filter to match the shape of the filter appropriate for your camera’s
image sensor size.
zDownload the filter template file (PDF).
zPrint the filter template out at full size (100%), and use it as the template to cut out the filter.
zT
he templates on this page are printed at full size, so can also be used. The filter template file is the same as this figure.
For full-frame cameras For APS-C cameras
Filter template outline
Full-frame
36.7 mm / 1.44 in.
29.4 mm / 1.16 in.
5.0 mm / 0.20 in.
3.5 mm / 0.14 in.
36.7 mm / 1.44 in.
8.0 mm / 0.31 in.
8.0 mm / 0.31 in.
8.0 mm / 0.31 in.
29.4 mm / 1.16 in.
APS-C
8.0 mm / 0.31 in.
Filter template outline

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z Only one gelatin filter with a thickness of 0.2 mm/0.008 in. or less may be used.
zWhen printing the template, make sure that the illustration size remains the same. Check that the printed-out
size is the same as the measurements shown in the illustration.
zCut the filter to the shape that matches your camera’s image sensor size.
zCut along the middle of the lines printed on the filter template. Any deviation from the template line width can
cause the following issues.
Note 1: If you cut inside the lines, light will come in around the edges of the filter, preventing it from working
fully. In particular, there can be differences with exposure and color patches in the corners.
Note 2: If you cut outside the lines, it may not fit in the holder, or the filter corners could contact the camera,
damaging the camera or filter.
Filters (Sold separately)

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Filters (Sold separately)
2Insert the filter from the left or right of the holder, and get it all within the projections on
both sides.
Filter indicators
Projections Bevel
Gelatin filter Contacts
zInsert the filter into the holder so that the bevel is on the
bottom right as shown in the figure on the left.
zInsert the filter so that it passes above the projections on the
left and right.
With a full-frame filter in place
Projection Projection
With an APS-C filter in place
Projection Projection
zFit filter between the projections on the left and right.
zCheck that the filter bevel is at the bottom right of the
contacts.
zImage ghosting may occur as a result of using a gelatin
filter. Also ensure that there is no dust or scratches on the
gelatin filter.
zWhen inserting a gelatin filter, ensure that you do not touch
the rearmost lens element.

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3Check the filter after insertion.
OK
When the bevel is
inside the diagonal line
When the bevel has
been cut too much
When the bevel has
not been cut enough
Fail (1) Fail (2)
zWhen using a full-frame filter, check that the bevel at the bottom right is as shown in the OK example when
the holder is on and the filter is pushed up to the top left.
zIf the filter is as shown in Fail (1), then the issues in Note 1 (p.14) may occur. If the filter is as shown in Fail (2),
then the issues in Note 2 (p.14) may occur.
zTake some test shots before shooting to check that the filter is working over the entire image.
zIn particular, take a telephoto image of a white wall with even brightness to check in your camera viewfinder
or on a monitor.
zThe gelatin filter may come out of place due to shocks or vibrations.
zCheck that the filter is correctly installed before shooting.
zWhen not using the camera for an extended period of time, remove the gelatin filter.
Filters (Sold separately)

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Specifications
Focal Length/Aperture 10-20mm f/4
Lens Construction 12 groups, 16 elements
Maximum Aperture f/4
Minimum Aperture f/22
Angle of View Horizontal: 121°55′ - 84°, Vertical: 100°25′ - 62°,
Diagonal: 130°25′ - 94°
Min. Focusing Distance 0.25 m/0.82 ft.
Max. Magnification 0.12x (at 20 mm)
Field of View Approx. 520 x 347 - 284 x 189 mm/
20.47 x 13.66 - 11.18 x 7.44 in. (at 0.25 m/0.82 ft.)
Filter Rear gelatin filter holder
Max. Diameter and Length Approx. 83.7 x 112 mm/3.30 x 4.41 in.
Weight Approx. 570 g/20.11 oz.
Hood Inbuilt
Lens Cap Lens Cap 10-20*
Lens Dust Cap Lens Dust Cap RF*
Case LP1219*
* This comes included with the lens, but can also be purchased separately.

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zThe lens length is measured from the lens mount surface to the front end of the lens.
Add 23.3 mm/0.92 in. when including the lens cap and dust cap.
zThe size and weight listed are for the lens only.
zYou cannot use extenders.
zMultiple exposure shooting is not possible when using this lens on certain cameras*.
* EOS R, RP, Ra, R5, R6
zThere are cases in which using the zoom function during continuous shooting may result in
conspicuous image distortion.
zAll data listed is measured according to Canon standards.
zProduct specifications and appearance are subject to change without notice.
Specications

CT1-D298-D 0923Ni © CANON INC. 2023