The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 10-17mm F3.5-4.5 ED Fisheye and the Pentax DFA645 Macro 90mm F2.8 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 DFA645 Macro 90mm F2.8 is the longer of the two lenses at 117mm. The Pentax 10-17mm F3.5-4.5 ED Fisheye with a length of 72mm, is 45mm shorter. Besides being longer, the Pentax DFA645 Macro 90mm F2.8 also has a larger diameter of 91mm compared to the Pentax 10-17mm F3.5-4.5 ED Fisheye's 68mm 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. Pentax 10-17mm F3.5-4.5 ED Fisheye weighs 320g, which means it is 720g (69%) lighter than the Pentax DFA645 Macro 90mm F2.8 which has a weight of 1040g.
Lens Mounts
The Pentax 10-17mm F3.5-4.5 ED Fisheye has the Pentax KAF lens mount whereas the Pentax DFA645 Macro 90mm F2.8 has the Pentax 645AF2 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 KAF Mount and Pentax 645Z, Pentax 645D and for the Pentax 645AF2 Mount.
Focal Range
Pentax 10-17mm F3.5-4.5 ED Fisheye has a focal range of 10-17mm and
1.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
15-25.5mm when used on a APS-C / DX format camera.
On the other hand, the Pentax DFA645 Macro 90mm F2.8 is a prime lens with fixed focal lenght of 90mm.
