Sigma have launched an 18-50mm f/3.5-5.6 DCzoom lens, exclusively designed
to suit the characteristics of digital SLR cameras. The image circle is
designed to match the size of the image sensors of digital SLR cameras.
The lens is compact with a maximum diameter of 60mm (2.3") and overall
length of 67.5mm (2.6") weighing only 245gr (8.6 ounces). It has
a variable angle of view of 76.5°?31.7°. The use of aspherical
lenses provides correction for various aberrations throughout the entire
zoom range and produce high level of optical performance. The 18-50mm
F3.5-5.6 DC lens has a minimum focusing distance of 25cm (9.8") at
all focal lengths and is capable of macro photography with a maximum magnification
ratio of 1:3.5.
Vignetting will occur if the lens is used with digital cameras with
image sensors larger than APS-C size or 35mm SLR cameras.
If Sigma SD9 or SD10 digital cameras are used, the angle of view will
be equal to 30-85mm focal length. The angle of view varies depending
on the camera.