Sigma AF 18-50 mm f/ 2.8 EX DC D Lens User Guide

 

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. 

These are special lenses that are designated for digital cameras because the lens image 
circle is designated to correspond to the size of the image sensors of most digital SLR 
cameras. The specialized design gives these lenses the ideal properties for digital cameras. 

 

◆  An image sensor element larger than those corresponding to APS-C cannot be used in 

digital cameras or 35mm SLR cameras. If such an element is used vignetting will occur 
on the picture surface. 

◆  If you use SD14 or SD10 or SD9 digital camera, corresponding angle of view will be 

30-340mm. 

When this lens is attached to the camera body it will automatically function in the same way 
as your normal 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.    To avoid damaging the lens, be 
especially sure to place the lens with its front end down while changing the lens. 

The sigma lens functions automatically after mounting to your camera.    Please, refer to the 
camera instruction book. 

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

 

◆  To avoid damaging AF mechanism, please do not turn the focus ring manually while in 

the autofocus mode. 

◆  The viewfinder of some Nikon AF cameras have indicators to display the focus status.  

The “

● ”  symbol indicates that correct focus has been set, “

►

”  indicates that focus is 

set in front of the subject, and “

◄

”  indicates that focus is set behind the subject.    When 

this AF lens is used with Nikon AF cameras in MF mode, please adjust the lens’ focus 
until the “

● ”  symbol is visible. 

◆  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 contact.    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 18mm and set the zoom lock switch to the 
“LOCK” position. (fig.2) 

The indication of the lens as “1:xx” on a focusing distance scale represent the magnification 
(commonly called the reproduction ratio).  For example when you are in focus at the 
“1:3.9” position on the scale, a subject with an actual size of 3.9cm will have an image size 
of 1cm on the firm. (fig.3) 

This OS lens effectively compensates for image blurring caused by camera shake. Using 
the Optical Stabilizer function it is possible to get sharp results at shutter speeds 
approximately 3-4 stops slower than you could without using the OS function. 

Set the OS switch to ON (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 from the time of depressing the shutter button halfway). 

 

◆  Do not use the Optical Stabilizer in the following situations: 

▪ When the lens is mounted on a tripod.      ▪ When using the camera in Bulb mode. 

◆  The 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 OS, please turn 
OFF

 the OS switch, in order to prevent unnecessary battery consumption. 

◆  Be sure to turn the OS switch to the OFF position before attaching or detaching the lens 

to the camera.   

◆  The OS 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 as this could damage the lens. 

◆  Although the viewfinder image may appear to shake immediately after shooting and/or at the start 

of the flash charge cycle of the camera’s built-in flash, it will not cause any effect to the pictures. 

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

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

A bayonet type detachable hood is provided with the lens.    This lens hood helps to prevent 
flare and ghosted images caused by bright illumination from outside the picture area.  
Attach the hood and turn clockwise until it stops rotation. (fig.5) 

 

◆  When taking photographs using the built-in flash, it is advisable to remove the lens hood so 

as to avoid cutting off any of the flash output, which could cause a shadow in the picture. 

◆  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.6) 

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

filters, like a polarizing filter, may cause vignetting. 

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

◆  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 you use the lens in the rain or near water, keep 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. 

 

Lens construction 

13 – 18 

Angle of View 

69.3 – 7.1° 

Minimum Aperture 

22 

Minimum Focusing Distance 

0.45m (1.48 ft) 

Magnification 1:3.9 
Filter Size 

72mm 

Dimensions Dia.

×Length 79×100mm (3.1×3.94 in) 

Weight 610g 

(21.5 

oz) 

Dimensions and weight include the SIGMA mount. 

 
 

The CE Mark is a Directive conformity mark of the European 

Community (EC). 

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

Verkauf: 01805-90 90 85-0 Service: 01805-90 90 85-85 Fax: 01805-90 90 85-35

 Filter Attachment Thread 
 Focus Ring 
 Distance Scale 
 Focus Index Line 
 Zoom Ring 

⑥ Focus Mode Switch 

⑦ Mount 

⑧ Zoom Lock Switch 

⑨ OS Switch 

⑩ Lens Hood