Canon lens EF 1740mm f4L USM User Manual

EF17-40mm f/4L USM
Instruction
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Thank you for purchasing a Canon product.
The Canon EF17-40mm f/4L USM is a high-
performance wide-angle zoom lens.
•“USM” stands for Ultrasonic Motor.Features
1. Two aspherical elements and a Super UD
element result in outstanding image
delineation.
2. Ultrasonic motor (USM) for quick and quiet autofocusing.
3. Manual focusing is available after the subject comes into focus in autofocus mode (ONE
SHOT AF).
4. A truly round aperture hole results in a nicer background blur.
5. Tight seal structure...

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aSafety Precautions
aSafety Precautions•Do not look at the sun or a bright light source
through the lens or camera. Doing so could result
in loss of vision. Looking at the sun directly through
the lens is especially hazardous.
• Whether it is attached to the camera or not, do
not leave the lens under the sun without the
lens cap attached. This is to prevent the lens from
concentrating the sun’s rays, which could cause a
fire.
Handling Cautions• If the lens is taken from a cold environment into
a...

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Nomenclature
Distance scale (→ 6)
Focus mode switch (
→ 5)
Lens mount index ( → 4)Contacts (
→ 4)
Hood mount (→ 7)
Focusing ring (→ 5) Gelatin filter holder (
→ 8)
Filter mounting
thread (→ 7) Zoom ring (→ 5)
F
or detailed information, reference page numbers are provided in parentheses ( →**).
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See your camera’s instructions for details on
mounting and detaching the lens.
1. Mounting and Detaching the Lens
The lens mount has a rubber ring for enhanced
w
ater- and dust-resistance. The rubber ring may
cause slight abrasions around the cameras lens
mount, but this will not cause any problems. If the
rub ber ring becomes worn, it is replaceable by a
Canon Service Center at cost.
• After detaching the lens, place the lens with the
rear end up to prevent the lens surface and
electrical contacts...

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3. Zooming
To  zoom, turn the lens’ zoom ring.
Be sure to finish zooming before focusing.
Changing the zoom ring after focusing can affect
the focus.
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
f ocusing ring. The focusing ring always works,
regardless of the focus mode.
2. Setting the Focus Mode
After autofocusing in ONE SHOT AF mode, focus
manually by pressing the shutter button...

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4.Infinity Compensation Mark
To  compensate for shifting of the infinity focus
point that results from changes in temperature.
The infinity position at normal temperature is the
point at which the vertical line of the L mark is
aligned with the distance indicator on the
distance scale.
F or accurate manual focusing on subjects at
infinity distance, look through the viewfinder while
rotating the focusing ring.
Infinity compensation mark
Distance index
The infrared index corrects the focus setting...

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You can attach filters to the filter mounting thread
on the front of the lens.
7. Filters (Sold separately)
•T o ensure dust- and water-resistant
performance, attach a Canon PROTECT filter
(77mm).
• Only one filter may be attached.
• If you need a polarizing filter, use the Canon
Circular Polarizing Filter (77mm).
6. Hood
The EW-83E hood can keep unwanted light out
of the lens, and also protects the front of the lens
from rain, snow, and dust.
To   attach the hood, align the hood’s attachment...

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There is a gelatin filter holder at the rear of the
lens. Cut the gelatin filter to fit within the white
frames. Then insert the gelatin filter into the filter
holder.
8. Filter Holder
•
Only one filter can be used.
• When you use a gelatin filter, ghosting may
appear in the image.
You can attach Extension Tube EF12 II or EF25
II for magnified shots. The shooting distance and
magnification are shown below.
9. Extension Tubes 
(Sold separately)
Camera-to-Subject  Magnification
Distance (mm)
Near Far...

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10. Close-up Lenses 
(Sold separately)
Attaching a 500D (77mm) Close-up Lens
enables close-up photography.
The magnification will be as follows: • Can be used at the 40mm end (magnification
0.30x - 0.08x)
• Close-up Lens 250D cannot be attached
because there is no size that fits the lens.
• Manual focusing is recommended for accurate
focusing.
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