The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Irix 11mm F4 and the Sigma 10-20mm F3.5 EX DC HSM 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. Irix 11mm F4 is the longer of the two lenses at 118mm. The Sigma 10-20mm F3.5 EX DC HSM with a length of 88mm, is 30mm shorter. Besides being longer, the Irix 11mm F4 also has a larger diameter of 103mm compared to the Sigma 10-20mm F3.5 EX DC HSM's 87mm 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. Sigma 10-20mm F3.5 EX DC HSM weighs 520g, 34% (270g) lighter than the Irix 11mm F4's weight of 790g.
Lens Mounts
Both the Irix 11mm F4 and the Sigma 10-20mm F3.5 EX DC HSM has the same Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with the Pentax KAF3 lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Irix 11mm F4 is also available in the Canon EF and Nikon F (FX) mounts.
Sigma 10-20mm F3.5 EX DC HSM is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Irix 11mm F4 is a prime lens with fixed focal lenght of 11mm.
On the other hand, the Sigma 10-20mm F3.5 EX DC HSM has a focal range of 10-20mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-30mm when used on a APS-C / DX format camera.
