The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-DA 11-18mm F2.8 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 a crucial factor to consider when comparing two lenses. HD Pentax-DA 11-18mm F2.8 is the longer of the two lenses at 100mm. The Pentax 15mm F4 ED AL L with a length of 40mm, is 60mm shorter. Besides being longer, the HD Pentax-DA 11-18mm F2.8 also has a larger diameter of 90mm compared to the Pentax 15mm F4 ED AL L's 63mm 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 15mm F4 ED AL L weighs 189g, 73% (515g) lighter than the HD Pentax-DA 11-18mm F2.8's weight of 704g.
Filter Threads
The HD Pentax-DA 11-18mm F2.8 has a filter size of 82mm whereas the Pentax 15mm F4 ED AL L has a 49mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the HD Pentax-DA 11-18mm F2.8:
And these are the 49mm filters that we recommend for the Pentax 15mm F4 ED AL L:
Lens Mounts
The HD Pentax-DA 11-18mm F2.8 has the Pentax KAF3 lens mount whereas the Pentax 15mm F4 ED AL L 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 KAF3 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Focal Range
HD Pentax-DA 11-18mm F2.8 has a focal range of 11-18mm and
1.6X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
16.5-27mm when used on a APS-C / DX format camera.
On the other hand, the 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.
