HD Pentax-DA 20-40mm F/2.8-4 ED DC WR Limited

Standard zoom lens • Digital era

Sample photos

20mm F/4
40mm F/8
40mm F/8
40mm F/5.6
40mm F/4
40mm F/8
40mm F/4
20mm F/4
20mm F/4

Abbreviations

HD Multi-layer High Definition coating is applied to the surfaces of lens elements. This anti-reflection coating boosts light transmission, ensures sharp and high contrast images, minimizes ghosting and flares.
DA Autofocus lens optimized for Pentax digital SLR cameras.
ED The lens incorporates low dispersion elements.
DC The lens is equipped with Direct Current motor.
WR Water-Resistant lens.

Features highlight

APS-C
1
ASPH
1
Super ED
1
ED
MM
QFS
9 blades
WR
SP
⌀55
filters
TC

Specification

Production details
Announced:November 2013
Production status: In production
Original name:HD PENTAX-DA 1:2.8-4 20-40mm ED Limited DC WR
System:Pentax K APS-C (2003)
Optical design
Focal length range:20mm - 40mm [2X zoom ratio]
Speed range:F/2.8 @ 20mm - F/4 @ 40mm
Maximum format:APS-C
Mount and Flange focal distance:Pentax K [45.5mm]
Diagonal angle of view:70.5° @ 20mm - 38.9° @ 40mm (Pentax K APS-C)
Lens construction:9 elements in 8 groups
1 ASPH, 1 Super ED, 1 ED
35mm equivalent focal length range and speed
35mm equivalent focal length range:30.6mm - 61.2mm (in terms of field of view)
35mm equivalent speed range:F/4.3 @ 20mm - F/6.1 @ 40mm (in terms of depth of field)
Zooming
Zoom mechanism:Manual
Zoom control:Zoom ring
Zoom type:Rotary
Zooming method:Extends while zooming
Focusing
Closest focusing distance:0.28m
Maximum magnification:1:5 @ 40mm at the closest focusing distance
Focusing modes:Autofocus, manual focus
Autofocus motor:Micromotor
Manual focus control:Focusing ring
Focus mode selector:None; focusing mode is set from the camera
Quick-Shift Focus System (QFS):Yes
Diaphragm mechanism
Diaphragm type:Automatic
Aperture control:None; the aperture is controlled from the camera
Number of blades:9 (nine)
Shake Reduction (SR)
Built-in SR:-
Physical characteristics
Weight:283g
Maximum diameter x Length:⌀71×68.5mm
Weather sealing:Water-resistant barrel
Super Protect (SP) coating:Front element
Accessories
Filters:Screw-type 55mm
Lens hood:MH-RA55 - Screw-type round
Teleconverters:HD Pentax-DA 1.4X AF Rear Converter AW → 28-56mm F/3.9-5.6
Source of data
Manufacturer's technical data.

Manufacturer description #1

2013.11.07 - RICOH IMAGING COMPANY, LTD. is pleased to announce the launch of the HD PENTAX-DA 20-40mmF2.8-4ED Limited DC WR interchangeable lens, designed for use with PENTAX K-mount lens-interchangeable digital cameras. Developed as the first zoom lens of the acclaimed Limited Lens series, this zoom lens features a lens-installed AF driving motor and a dependable weather-resistant construction.

This model is the first zoom lens of the high-grade Limited Lens series, which is renowned for its exceptional visual description, distinctive appearance and meticulous finish in every detail. It features a two-times zoom range covering focal lengths from moderate wide angle to standard, and a large maximum aperture of F2.8 at its wide-angle end. In addition to the state-of-the-art HD coating and completely round-shaped diaphragm, it also comes equipped with a weather-resistant construction for the first time in the Limited Lens series, and a smooth, quiet AF system driven by a lens-installed AF motor, to capture beautiful, high-quality images, even under demanding weather and environmental conditions.

Main Features

1. The first two-times zoom lens of the Limited Lens series

With its two-times zoom coverage from 20mm to 40mm, this lens offers a focal-length coverage from 30.5mm to 61.5mm (in the 35mm format) when mounted on a PENTAX K-series lens-interchangeable digital cameras body. It provides the most frequently used focal lengths required for many popular applications, such as scenic photography, snapshots and portraiture, making it the ideal choice as an all-purpose, everyday lens.

2. Acclaimed Limited Lens-series quality for superb visual description and premium appearance

Inheriting the design concept of the Limited Lens series, this lens is designed with an optical construction that faithfully reproduces the feeling of depth while minimizing astigmatism over the entire zoom range. It allows the photographer to optimize the subject's visual description, by making its appearance softer at larger apertures and sharper at smaller apertures. Its lens barrel, hood and cap are made of a high-grade aluminum material, and hand-machined for perfect proportions and beautiful texture. Positioned in the mid-section of the lens barrel, the zoom ring features a series of knurled grooves to facilitate zooming operation.

3. State-of-the-art optical technology

The lens has been treated with the PENTAX-developed HD coating*, a high-grade, multi-layer coating that reduces reflectance in the visible light spectrum to less than 50 percent of that of conventional multi-layer coatings. This allows the user to capture crisp, high-contrast images free of flare and ghost images, even under such adverse lighting conditions as backlight. It also incorporates an ED (Extra-low Dispersion) glass and a super-low-dispersion glass element in its optics to deliver clear, high-resolution images with edge-to-edge sharpness, while effectively compensating for chromatic aberrations over the entire zoom range.

* HD stands for High Resolution.

4. The first weather-resistant lens in the Limited Lens series

This lens is the first Limited Lens-series model to feature a weather-resistant construction, with seven special seals to prevent the intrusion of water and moisture into the lens interior. By mounting it on a PENTAX weather-resistant digital SLR camera body, the user is assured of greater durability and reliability when shooting in the rain or mist, as well as at locations subject to spray or splashes.

5. Other features

  • Smooth, quiet AF operation using a lens-installed AF driving motor.
  • Round-shaped diaphragm to produce a natural, beautiful bokeh (blur) effect, while minimizing the streaking effect of point light sources.
  • The lens features the Quick-Shift Focus System, which allows the user to instantly switch to manual-focus operation after the subject is captured in focus by the camera's AF system.
  • SP (Super Protect) coating to keep the front surface free of dust and stains.
  • A choice of black or silver color.

Manufacturer description #2

As the first zoom lens in Ricoh Imaging’s acclaimed Limited Lens series , this lens features a versatile focal length of from 30.5mm to 61.5mm (in the 35mm format) , ideal for a variety of subjects, settings and creative perspectives, all housed in a durable weather sealed body with state-of-the-art High Definition (HD) coating. With its large F2.8 maximum aperture and rounded diaphragm blades, the HD PENTAX DA 20-40mm F2.8-4 ED Limited DC WR lens produces stunning bokeh for exceptional visual expression. The in-lens direct current (DC) focus motor provides fast, quiet and smooth autofocus functionality.

Manufacturer description #3

Featuring the newest HD coating, round iris diaphragm, and weather-resistant construction, this single lens enables shooting from the wide angle to medium telephoto ranges. This lens covers the range from wide angle to medium telephoto and provides a natural perspective that is close to the view of human eye. This 2X lens is suitable for day-to-day use that supports a wide range of photography, including landscapes and portraits. As would be expected from the newest lens, it features sharp, detailed imaging with a soft rendering effect. This lens has a weather-resistant construction, and it can be used to configure the ideal photography system by combining with dust-resistant, weather-resistant PENTAX digital SLR cameras.

This coating reduces the reflection rate up to 50% more than the conventional coating (compared to PENTAX multicoating) for reduced flare and ghosting even under backlighting and other adverse conditions where strong point light sources can enter the lens.

A 9-blade, round iris diaphragm is used. This enables natural reproduction of illumination and other scenes and softer out-of-focus (bokeh) effects for making the subject stand out more prominently from the background.

ED (Extra-low Dispersion) Glass and Anomalous Dispersion Glass are used to minimize color blurring over the entire zoom range and even at the edges of the image for providing superior resolution.

For the first time, the Limited series now uses a DC motor inside the lens barrel for providing a focusing mechanism. Compared to body AF, this focusing mechanism provides a quieter drive sound and smoother AF operation.

Photography when exposed to water or sudden rainfalls A weather-resistant construction is used for overcoming adverse conditions. The focus ring and zoom ring also have a weather-resistant design for preventing the entry of water.

The lens barrel, cap, and hood use a machined aluminum material. You will feel the presence and elegance of the Limited series whenever you look at or touch this lens.

Typical application

Class:

Slow APS-C-format standard zoom lens • Technical masterpieceTravellers' choice

Technical masterpiece

This Limited lens is not only capable of producing excellent photos, but also gives aesthetic pleasure to its owner.

  • Machined aluminum lens barrel
  • Elegant shape and distinctive appearance
  • Compact, lightweight design
  • Recessed distance scale
  • Exclusively designed lens hoods and caps

Travellers' choice

  • Lightweight
  • Water-resistant barrel
  • Super Protect (SP) coating

Missing features (3):

16mm at the wide end • Constant speed across the focal length range • More efficient autofocus motor

Genres or subjects of photography (12):

Landscapes • Cityscapes • Buildings • Interiors • Portraits • Photojournalism • Weddings • Parties • Carnivals • Live concerts • Street • Travel photography

Recommended slowest shutter speed when shooting static subjects handheld:

1/40th of a second @ 40mm • 1/20th of a second @ 20mm

Alternatives in the Pentax K APS-C system

Sorted by focal length and speed, in ascending order

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Table of contents
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Pros and cons
Instruction manual
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Pentax Limited series lenses (18)
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Pentax Limited series lenses

Pentax cameras are traditionally developed on the foundation of being small and light. The Limited lenses match that type of small body by being small yet high quality interchangeable AF lenses. The pillars of the Limited lenses concept is small size, high image quality optical formula, and a corresponding outer shape to go with it. Thus, the Limited lenses are not only capable of producing excellent photos, but also give aesthetic pleasure to their owners

Pentax-DA series lenses (47)
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Pentax Limited series lenses

Pentax cameras are traditionally developed on the foundation of being small and light. The Limited lenses match that type of small body by being small yet high quality interchangeable AF lenses. The pillars of the Limited lenses concept is small size, high image quality optical formula, and a corresponding outer shape to go with it. Thus, the Limited lenses are not only capable of producing excellent photos, but also give aesthetic pleasure to their owners

Pentax-DA series lenses

The smc Pentax-DA lenses can be used exclusively with Pentax digital SLR cameras. Their image circle is specialized for image sensors in Pentax digital SLR cameras and their optical systems are optimized for the characteristics of digital images. The DA lenses are not compatible with film SLR cameras.

The DA lenses do not have an aperture ring. Aperture settings are controlled automatically as if set to the auto "A" position.

When autofocusing is finished, it is possible to make fine adjustments by hand using the "Quick-Shift Focus System".

There are four mounts for the DA lenses, the KAF (with AF coupler), KAF2 (with AF coupler AND supersonic motor), KAF3 (with supersonic motor ONLY), and KAF4 (with electromagnetic diaphragm ONLY).

Copyright © 2012-2023 Evgenii Artemov. All rights reserved. Translation and/or reproduction of website materials in any form, including the Internet, is prohibited without the express written permission of the website owner.

35mm full frame

43.27 24 36
  • Dimensions: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2

Micromotor

Aspherical elements

Aspherical elements (ASPH, XA, XGM) are used in wide-angle lenses for correction of distortion and in large-aperture lenses for correction of spherical aberration, astigmatism and coma, thus ensuring excellent sharpness and contrast even at fully open aperture. The effect of the aspherical element is determined by its position within the optical formula: the more the aspherical element moves away from the aperture stop, the more it influences distortion; close to the aperture stop it can be particularly used to correct spherical aberration. Aspherical element can substitute one or several regular spherical elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Use of aspherical elements has its downsides: it leads to non-uniform rendering of out-of-focus highlights. This effect usually appears as "onion-like" texture of concentric rings or "wooly-like" texture and is caused by very slight defects in the surface of aspherical element. It is difficult to predict such effect, but usually it occurs when the highlights are small enough and far enough out of focus.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Canon's Super UD, Nikon's Super ED, Pentax' Super ED, Sigma's FLD ("F" Low Dispersion), Sony' Super ED and Tamron's XLD glasses are the highest level low dispersion glasses available with extremely high light transmission. These optical glasses have a performance equal to fluorite glass.

High-refraction low-dispersion elements

High-refraction low-dispersion elements (HLD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

High Index, High Dispersion elements

High Index, High Dispersion elements (HID) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Anomalous partial dispersion elements

Anomalous partial dispersion elements (AD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Fluorite elements

Synthetic fluorite elements (FL) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. Compared with optical glass, fluorite lenses have a considerably lower refraction index, low dispersion and extraordinary partial dispersion, and high transmission of infrared and ultraviolet light. They are also significantly lighter than optical glass.

According to Nikon, fluorite easily cracks and is sensitive to temperature changes that can adversely affect focusing by altering the lens' refractive index. To avoid this, Canon, as the manufacturer most widely using fluorite in its telephoto lenses, never uses fluorite in the front and rear lens elements, and the white coating is applied to the lens barrels to reflect light and prevent the lens from overheating.

Short-wavelength refractive elements

High and specialized-dispersion elements (SR) refract light with wavelengths shorter than that of blue to achieve highly precise chromatic aberration compensation. This technology also results in smaller and lighter lenses.

Blue Spectrum Refractive Optics

Organic Blue Spectrum Refractive Optics material (BR Optics) placed between convex and concave elements made from conventional optical glass provides more efficient correction of longitudinal chromatic aberrations in comparison with conventional technology.

Diffraction elements

Diffraction elements (DO, PF) cancel chromatic aberrations at various wavelengths. This technology results in smaller and lighter lenses in comparison with traditional designs with no compromise in image quality.

High refractive index elements

High refractive index elements (HR, HRI, XR etc) minimize field curvature and spherical aberration. High refractive index element can substitute one or several regular elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Apodization element

Apodization element (APD) is in fact a radial gradient filter. It practically does not change the characteristics of light beam passing through its central part but absorbs the light at the periphery. It sort of softens the edges of the aperture making the transition from foreground to background zone very smooth and results in very attractive, natural looking and silky smooth bokeh.

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Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film.

The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.

Format

Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Imaging sensors are sometimes smaller than 35mm film frame, and this causes the lens to have a narrower angle of view than with 35mm film, by a certain factor for each sensor (called the crop factor).

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),

where:

CF – crop-factor of a sensor,
FL – focal length of a lens.

Mount

A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.

Speed

The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. For example, a magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size".

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

The lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value.

Semi-automatic diaphragm

The lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value.

Automatic diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/2.8 on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.

Weight

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

A rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.

Filters

Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background.

The geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.

Teleconverters

Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.

Rotary zoom

The change of focal length is achieved by turning the zoom ring and the manual focusing - by turning the separate focusing ring.

Push/pull zooming allows for faster change of focal length, however conventional method based on the rotation of the zoom ring provides more accurate and smooth zooming.

Push/pull zoom

The change of focal length happens when the photographer moves the ring towards the mount or backwards.

Push/pull zooming allows for faster change of focal length, however conventional method based on the rotation of the zoom ring provides more accurate and smooth zooming.

Zoom lock

The lens features a zoom lock to keep the zoom ring fixed. This function is convenient for carrying a camera with the lens on a strap because it prevents the lens from extending.

Zoom clutch

To set the manual zoom mode, pull the zoom ring towards the camera side until the words "POWER ZOOM" disappear.