Sigma HSM 17-50mm F2.8 EX DC Auto Focus
Wide Lens Pentax
Sigma just released their all new AF 17-50mm f/2.8 HSM DC EX Auto Focus
Lens. That alone may not be all that exciting - we've seen many fast
standard zoom lenses by Sigma come and go - but this one is a bit more special.
Recently Sigma announced a couple of lenses featuring their brand new FLD glass
and the new 17-50mm f/2.8 OS is among them. FLD glass has an
optical characteristic similar to fluorite glass. Such glass elements can be
used to compensate optical aberrations (defects) more efficiently than
conventional "special" elements such as Sigma's more commonly used SLD glass.
Professional Photographers are already impressed by the performance of the
Sigma AF 8-16mm f/4.5-5.6 HSM DC which does also benefit from FLD
elements so there's some well founded hope that the AF 17-50mm f/2.8 HSM
DC stands out-of-the-ordinary as well.
For Pentax mount, the built-in OS function of this Sigma HSM 17-50mm
F2.8 EX DC OS lens can be used even if the camera body is equipped with an
image sensor shift anti-shake system. As compensation for camera shake is
visible in the viewfinder, the photographer can easily check for precise focus
and make sure there is no subject movement. The optical stabilizer OS function
is not available for Pentax mounts
Specifications - Sigma HSM 17-50mm F2.8 EX DC Auto Focus Wide
13 groups 17 elements
• 2 FLD glass elements
Angle of view
Closest focus distance
28cm / 11in
Maximum reproduction ratio
Filter attachment size
83.5mm x 91.8.8mm (3.3in × 3.6in)
Kit Content Sigma HSM 17-50mm F2.8 EX DC OS Auto Focus Wide Lens
Petal-type Hood (LH825-03)
For more information about, Sigma HSM 17-50mm F2.8 EX DC Auto Focus Wide Lens Pentax website.