The 24mm World Cup
Group C: Regular f2.8 Prime Lenses
Preliminary Knockout Round: Sigma 24mm f2.8 v Pentax 24mm SMC-A
The recent availability of Pentax to Canon EF/EOS adapors makes it possible to include the highly regarded Pentax 24mm SMC and FA lenses in the test. Their use on EF-S mount cameras is straightforward, but when used on a full frame 35mm sensor, the stop down lever on the rear of the lens mount has to be shortened lest it fouls the mirror box. This is a one-way ticket to Canon compatibility and therefore not to be undertaken unless one is convinced about the benefits of doing so. Naturally, until the lens is tested, that remains unproven.
So, we have to watch a final warm-up friendly before the main event begins: here, two Pentax K-mount lenses are tested on a Canon 350D at a range of approximately one metre: the Pentax SMC-A f2.8 and a K-mount Sigma 24mm f2.8 SuperWide II manual focus model. Your referee for this match is the Canon 24mm f2.8.
The SMC-A is considered by many to be Pentax' finest 24mm prime: consistently outperforming the later M version, despite apparently being of identical optical design. There is another school of thought that prefers the much later autofocus 24mm FA f2, but that will be explored later in Group B, where it competes with the Sigma 24mm f1.8, Canon 24mm L and Nikon 24mm f2.
All files shot at ISO 100; RAW files were developed in Phase C1. Photoshop USM was applied equally to all captures (125 / 0.5 / 3). Lighting was quick-and-dirty in-camera flash.