The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax D FA 70-200mm F2.8ED and the Sigma 50-200mm F4-5.6 DC OS HSM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Pentax D FA 70-200mm F2.8ED is the longer of the two lenses at 203mm. The Sigma 50-200mm F4-5.6 DC OS HSM with a length of 102mm, is 101mm shorter. Besides being longer, the Pentax D FA 70-200mm F2.8ED also has a larger diameter of 92mm compared to the Sigma 50-200mm F4-5.6 DC OS HSM's 74mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Sigma 50-200mm F4-5.6 DC OS HSM weighs 420g, 76% (1335g) lighter than the Pentax D FA 70-200mm F2.8ED's weight of 1755g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Pentax KAF3 Mount for size comparison purposes.
Telephoto Lenses in Pentax KAF3 Mount for Size Comparison
Filter Threads
The Pentax D FA 70-200mm F2.8ED has a filter size of 77mm whereas the Sigma 50-200mm F4-5.6 DC OS HSM has a 55mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Pentax D FA 70-200mm F2.8ED:
And these are the 55mm filters that we recommend for the Sigma 50-200mm F4-5.6 DC OS HSM:
Lens Mounts
Both the Pentax D FA 70-200mm F2.8ED and the Sigma 50-200mm F4-5.6 DC OS HSM has the same Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with the Pentax KAF3 lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Sigma 50-200mm F4-5.6 DC OS HSM is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Pentax D FA 70-200mm F2.8ED has a focal range of 70-200mm and
2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
105 - 300mm.
On the other hand, the Sigma 50-200mm F4-5.6 DC OS HSM has a focal range of 50-200mm and 4.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 75-300mm when used on a APS-C / DX format camera.
