Sigma 728 DATASHEET

ENGLISH

Thank you very much for purchasing a Sigma Lens. In order to get the maximum
performance and enjoyment out of your Sigma lens, please read this instruction
booklet thoroughly before you start to use the lens.

DESCRIPTION OF THE PARTS (fig.1)

① Filter Attachment Thread
② Focus Ring
③ Distance Scale
④ Focus Index Line

 Zoom Ring
 Focus Mode Switch
 Mount
 Tripod Socket

NIKON AF TYPE CAMERAS

This lens functions in the same way as a G Type auto-focus Nikon lens (without
an aperture ring). Functions may be restricted depending on the lens/camera
combination. For more details, please refer to the camera’s instruction manual.

PENTAX AF TYPE CAMERAS

This Lens functions same as a FAJ Type (type without Aperture) auto-focus
Pentax lens. Depending on the combination with camera some restrictions with
its functions may result. For more details, please refer to instruction manual of
the camera in use etc.

ATTACHING TO CAMERA BODY

When this lens is attached to the camera body it will automatically function in the
same way as the camera manufacturer ’s lens. Please refer to the instruction
booklet for your camera body.

◆ On the lens mount surface, there are a number of couplers and electrical

contacts. Please keep them clean to ensure proper connection.

◆

While changing the lens, be sure to place it front end down to avoid damaging the
rear mount.

SETTING THE EXPOSURE MODE

The Sigma lens functions automatically once attached to the camera. Please
refer to the camera instruction book.

FOCUSING AND ZOOMING

This lens features Sigma’s built-in Hyper Sonic Motor (HSM). The HSM
enables quick and quiet autofocusing.

《

SIGMA AF and CANON AF》

For autofocus operation, set the focus mode switch on the lens to the “AF”
position (fig.2). If you wish to focus manually, set the focus mode switch on the
lens to the “M” position. You can adjust the focus by turning the focus ring.

《

NIKON AF, PENTAX AF, and SONY》

For autofocus operation, set the camera to AF mode and set the focus mode
switch on the lens to the “AF” position (fig.2). If you wish to focus manually, set
the focus mode switch on the lens to the “M” position. You can adjust the focus
by turning the focus ring.

◆ Please refer to camera’s instruction manual for details on changing the

camera’s focusing mode.

◆ For Nikon, Pentax and Sony mounts, it is only possible to use AF with camera

bodies which support motors driven by ultrasonic waves such as HSM. AF
will not function if the camera body does not support this type of motor.

◆ This lens also permits manual focusing even in the autofocus mode. With

the camera set to the One-Shot AF (AF-S) mode, it is possible to manually
override the autofocus while the shutter release button is pressed halfway.

◆ When operating this lens in manual focus mode, it is recommended that

correct focus be confirmed visually in the viewfinder rather than relying on the
distance scale. This is due to possible focus shift resulting from extreme
changes in temperature which cause various components in the lens to
expand and contract. Special allowance is made for this at the infinity
setting.

《Zooming》

Rotate the Rubber grip on the zoom ring to the desired position.

ZOOM LOCK SWITCH

This lens is also equipped with Zoom Lock Switch to eliminate the zoom creep
when the lens is tilted down. Please set zooming ring to 120mm and set the
zoom lock switch to the “LOCK” position, (fig.3), however, please slide the lens
to the “UNLOCK” position from “LOCK” position, before taking the picture.

ABOUT OS (OPTICAL STABILIZER) FEATURES

(except Pentax AF and SONY mount)

This OS

(Optical Stabilizer)
caused by camera shake.
With this lens, you can take pictures at shutter speeds approx 4 steps slower
than you could without using the OS function of this lens and can get sharp
results.
Set the OS（Optical Stabilizer）switch to Mode 1 (fig. 4). Press the shutter button
halfway down, confirm the image in the viewfinder is stable then take the picture.
(It takes approximately 1 second to produce a stable image, after pressing the
shutter button halfway). Mode
overcomes blurring. It is effective on subjects moving horizontal to the camera.

◆ The blurring compensation function of Optical Stabilizer is effective for

hand-held shooting. In the following conditions, Optical Stabilizer may not
function properly.

▪ Shots from the a moving vehicle ▪ If there is a considerable camera motion

or shake.

◆ Please do not use Optical Stabilizer in the following situations.

▪ When the lens is mounted on a tripod. ▪ Bulb (long time exposure).

lens effectively compensates for image blurring

2

, detects the vertical camera shake, and

 Zoom Lock Switch
 OS Switch
(except Pentax AF and SONY mount)
 Lens Hood

◆ Optical Stabilizer function is powered from the camera. If the OS lens is

attached to your camera and activated, shooting capacity of your camera will
be lower than with conventional lenses used with the same camera. If you are
not using Optical Stabilizer, please turn OFF the OS switch, in order to prevent
consumption of a battery.

◆ Be sure to turn of OS switch to OFF position, before attaching or detaching

the lens to the camera.

◆ The Optical Stabilizer continues to operate after you release your finger from

the shutter button, as long as the exposure meter displays the exposure value.
Never remove the lens or remove the camera’s battery while the image
stabilizer is operating, you could damage the lens.
Although the viewfinder image may appear to shake immediately after shooting

◆

and at the start of the flash charge cycle of the built-in flash of the camera etc., it
will not cause any effect on pictures.

◆ If the camera power is turned off or lens is detached while the Optical

Stabilizer function is in operation, the lens may emit a chattering noise, but this
is not a malfunction.

◆ Optical Stabilizer feature can work with the Nikon AF cameras shown in the

following table. When using this lens with other camera models not listed in
the following table, please set the OS Switch to OFF position to cancel the
Optical Stabilizer function.

Digital SLR Cameras and F6, F5, F100, F80/N80, U (F65/N65), U2 (F75/N75)

※From our homepage, you can check the latest information regarding the
camera models, which can be used with Optical Stabilizer function.

TRIPOD SOCKET AND COLLAR

This lens is equipped with a tripod socket. When you loosen the locking knob on the
collar, the lens and camera can rotate freely to easily position the camera
horizontally or vertically (fig.5).

HOW TO REMOVE THE TRIPOD COLLAR

1. It is possible to remove the lens’ tripod socket, for more convenient hand-held
photography, if desired. To do so, first loosen the tripod collar locking knob,
and, align the index mark of the collar, with the ▼REMOVE position (fig.6).

2. Then, pull the tripod collar straight back, as shown in Fig.7, removing the
collar.

When you wish to re-attach the tripod collar to the lens, please reverse the

◆

procedure above.

◆ Please, do not set the tripod collar to the ▼REMOVE position, except when

you are removing, or attaching, the tripod collar, as the lens may inadvertently
detach from the collar and fall. Also, please remember to tighten the locking
knob to prevent the lens from rotating unintentionally.
When the lens is mounted on the camera, the tripod collar cannot be removed

◆

from the lens.

SHOULDER STRAP

Please attach the shoulder strap to the sling as described in figure 8.

FLASH PHOTOGRAPHY

The camera’s built-in flash will cause barrel shadow if used with this lens. For
best results, please only use an external flash unit.

ABOUT TELE CONVERTERS

The lens can be used with Sigma’s 1.4x EX or 2.0x EX Apo Tele Converters
(optional), becoming a 168-560mm F6.3-8 telephoto zoom lens or a 240-800mm
F9-11 telephoto zoom lens respectively （both can be used in manual focus
only）.

◆ Do not use other manufacturers’ teleconverter’s, only those listed above are

compatible.

◆ The Pentax mount Tele Converter is not compatible with this particular lens.

◆ We recommend the DG APO Tele-Converters when using with DSLR

cameras.

LENS HOOD

A bayonet type detachable `hood is provided with the lens. This lens hood
helps to prevent flare and ghosted images caused by extraneous light. Attach
the hood and turn clockwise until it stops rotating. (fig.9)

◆ In order to place the lens and hood into the storage case, you must first

remove the hood, then replace it on the lens in the reverse position. (fig.10)

FILTER

◆ Only one filter should be used at a time. Two or more filters and/or special,

thicker filters, such as a polarizing filter, may cause vignetting.

◆ When using a polarizing filter with an AF camera, use the “circular” type.

BASIC CARE AND STORAGE

◆ Avoid any shocks or exposure to extreme high or low temperatures or to

humidity.

◆ For extended storage, choose a cool and dry place, preferably with good

ventilation. To avoid damage to the lens coating, keep away from mothballs or
naphthalene gas.
Do not use thinner, benzine or other organic cleaning agents to remove dirt or

◆

finger prints from the lens elements. Clean by using a soft, moistened lens
cloth or lens tissue.

◆ This lens is not waterproof. When using the lens in the rain or near water,

prevent it from getting wet. It is often impractical to repair the internal
mechanism, lens elements and electric components damaged by water.

◆ Sudden temperature changes may cause condensation or fog to appear on

the surface of the lens. When entering a warm room from the cold outdoors,
it is advisable to keep the lens in the case until the temperature of the lens
approaches room temperature.

TECHNICAL SPECIFICATIONS

Lens construction 15 – 21
Angle of View 20.4 – 6.2°
Minimum Aperture 22
Minimum Focusing Distance 1.5m (4.92 ft)
Magnification 1:4.2
Filter Size 77mm
Dimensions Dia.×Length 92.5×203.5mm (3.64×8.01 in)
Weight 1750g (61.7 oz)

Dimensions and weight include the SIGMA mount.

SIGMA (Deutschland) GmbH Carl-Zeiss-Str. 10/2, D-63322 Rödermark, F.R.GERMANY

The CE Mark is a Directive conformity mark of the European
Community (EC).

Verkauf: 01805-90 90 85-0 Service: 01805-90 90 85-85 Fax: [phone]