The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax FA 70-210mm F4 ED SDM WR and the Sigma 18-300 F3.5-6.3 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 FA 70-210mm F4 ED SDM WR is the longer of the two lenses at 175mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 73mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 79mm.
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 18-300 F3.5-6.3 DC OS HSM weighs 585g, 28% (234g) lighter than the Pentax FA 70-210mm F4 ED SDM WR's weight of 819g.
Filter Threads
The Pentax FA 70-210mm F4 ED SDM WR has a filter size of 67mm whereas the Sigma 18-300 F3.5-6.3 DC OS HSM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Pentax FA 70-210mm F4 ED SDM WR:
And these are the 72mm filters that we recommend for the Sigma 18-300 F3.5-6.3 DC OS HSM:
Lens Mounts
The Pentax FA 70-210mm F4 ED SDM WR has the Pentax KAF4 lens mount whereas the Sigma 18-300 F3.5-6.3 DC OS HSM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF4 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount.
Sigma 18-300 F3.5-6.3 DC OS HSM is also available in Canon EF , Nikon F (DX), Sigma SA and Sony Alpha mounts.
Focal Range
Pentax FA 70-210mm F4 ED SDM WR has a focal range of 70-210mm and
3.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
105-315mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and 16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-450mm when used on a APS-C / DX format camera.
