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 Tamron AF 18-250mm f3.5-6.3 II LD 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 Tamron AF 18-250mm f3.5-6.3 II LD with a length of 84mm, is 91mm shorter. Besides being longer, the Pentax FA 70-210mm F4 ED SDM WR also has a larger diameter of 79mm compared to the Tamron AF 18-250mm f3.5-6.3 II LD'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. Tamron AF 18-250mm f3.5-6.3 II LD weighs 430g, 47% (389g) 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 Tamron AF 18-250mm f3.5-6.3 II LD has a 62mm 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 62mm filters that we recommend for the Tamron AF 18-250mm f3.5-6.3 II LD:
Lens Mounts
The Pentax FA 70-210mm F4 ED SDM WR has the Pentax KAF4 lens mount whereas the Tamron AF 18-250mm f3.5-6.3 II LD has the Pentax KAF 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 KAF Mount.
Tamron AF 18-250mm f3.5-6.3 II LD is also available in Canon EF , Nikon F (DX) 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 Tamron AF 18-250mm f3.5-6.3 II LD has a focal range of 18-250mm and 13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-375mm when used on a APS-C / DX format camera.
