Sigma 28mm F1.8 EX DG
ASPHERICAL MACRO
Data from Sigma web site, review from Rusty Dodson
The large aperture wide-angle lens for digital and 35mm film
SLR cameras.
This lens has a macro focusing capability with fast F1.8 maximum aperture, which
is ideal for Digital SLR cameras.
Macro capability
This lens is capable of Macro photography, with minimum shooting distance of
20cm (7.8 inch) (reproduction ratio 1 : 2.9) and angle of view is 75.4. You can
take picture not only the subject but also the surrounding scenery.
Large front element and Super wide-angle
The lens has an advanced optical construction, in order to obtain adequate
peripheral brightness with open aperture. Also, the iris diaphragm has 9
diaphragm blades to obtain beautiful out of focus images in the foreground and
background.
Handling
The lens incorporates a Dual-Focus (DF) mechanism. It is easy to hold the lens,
since the focusing ring does not rotate during auto-focus, yet it provides
adequate focusing torque of the focusing ring during manual focusing of the
lens. Also, this also allows the use of a Petal-type Hood and the easy use of a
polarizing filter.
Aspherical lens
It incorporates a floating focus system and uses two aspherical lens elements
for minimizing distortion, aberration and astigmatism.
Lens Construction
10 Elements in 9 Groups
Angle of View 75.4 degrees
Number of Diaphragm Blades 9 Blades
Minimum Aperture F22
Minimum Focusing Distance 20cm/7.9 in.
Maximum Magnification 1:2.9
Filter Size Diameter 77mm
Dimensions Diameter 83.6mm X Length 82.5mm
3.3 in. X 3.2 in.
Weight 500g/17.6 oz.
Corresponding AF Mounts SIGMA, CANON, NIKON (D), SONY/MINOLTA (D), PENTAX
My main reason for the lens was for indoor work with flash. For this purpose I am happy!
The Sigma 28mm f1.8 macro lens does get the job done. The f1.8 aperture is fast enough for indoor natural light photography and this lens has the smoothest bokeh I've seen on a wide angle lens. Of course on a Dslr this is not a true wide angle.
The image sharpness is decent wide open at reasonable close range. An f1.8 lens takes some skill at getting the depth of field perfect at any distance. Stopped down the Sigma 28mm lens actually does perform decent as a macro lens. At f1.8 sharpness is usable, at f2.8 it just gets better.
The Sigma 28mm appears to be built pretty well, decent weight and feel. The hood is somewhat tiresome to take off and replace.
The real weak spot of this lens is the auto focus. The focus speed and noise is among the worst I've ever used.
Overall the lens is suitable for professional work when used in an environment that allows for noise and for slow moving objects.