The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-FA 35mm F2 AL and the Tamron 17-50mm f2.8 XR 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. Tamron 17-50mm f2.8 XR II LD is the longer of the two lenses at 82mm. The HD Pentax-FA 35mm F2 AL with a length of 45mm, is 37mm shorter. Besides being longer, the Tamron 17-50mm f2.8 XR II LD also has a larger diameter of 74mm compared to the HD Pentax-FA 35mm F2 AL's 64mm 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. HD Pentax-FA 35mm F2 AL weighs 193g, which means it is 237g (55%) lighter than the Tamron 17-50mm f2.8 XR II LD which has a weight of 430g.
Filter Threads
The HD Pentax-FA 35mm F2 AL has a filter size of 49mm whereas the Tamron 17-50mm f2.8 XR II LD has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 49mm filters that we recommend you to consider for the HD Pentax-FA 35mm F2 AL:
And these are the 67mm filters that we recommend for the Tamron 17-50mm f2.8 XR II LD:
Lens Mounts
Both the HD Pentax-FA 35mm F2 AL and the Tamron 17-50mm f2.8 XR II LD has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Tamron 17-50mm f2.8 XR II LD is also available in Canon EF , Nikon F (DX) and Sony Alpha mounts.
Focal Range
HD Pentax-FA 35mm F2 AL is a prime lens with fixed focal lenght of 35mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
52.5mm.
On the other hand, the Tamron 17-50mm f2.8 XR II LD has a focal range of 17-50mm and 2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-75mm when used on a APS-C / DX format camera.
