The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 14mm F2.8 ED and the Pentax 15mm F4 ED AL L for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Pentax 14mm F2.8 ED is the longer of the two lenses at 69mm. The Pentax 15mm F4 ED AL L with a length of 40mm, is 29mm shorter. Besides being longer, the Pentax 14mm F2.8 ED also has a larger diameter of 84mm compared to the Pentax 15mm F4 ED AL L's 63mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Pentax 15mm F4 ED AL L weighs 189g, 55% (231g) lighter than the Pentax 14mm F2.8 ED's weight of 420g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Pentax KAF Mount for size comparison purposes.
Wideangle Prime Lenses in Pentax KAF Mount for Size Comparison
Lens Mounts
Both the Pentax 14mm F2.8 ED and the Pentax 15mm F4 ED AL L 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 Monochrome, Pentax KF and Pentax K-3 III.
Focal Range
Pentax 14mm F2.8 ED is a prime lens with fixed focal lenght of 14mm which has an effective (full-frame 35mm equivalent) focal range of 21mm when used on a APS-C / DX format camera. Pentax 15mm F4 ED AL L is a prime lens with fixed focal lenght of 15mm which has an effective (full-frame 35mm equivalent) focal range of 22.5mm when used on a APS-C / DX format camera.