Both the Sigma DP2m and SD1 are fine cameras which appeal to different target groups and which reach top forms under different conditions. The DP2m is a compact camera capable of astonishing image quality – the full format for the jacket pocket, so to speak. This compactness comes with disadvantages as well, lenses cannot be changed, one has to make do with a fixed normal focal length. The SD1 is equipped with the same foveon sensor and performs similarly, but having a lens mount, it provides the possibility of changing lenses in order to be all geared up for any motif whatsoever. What happens, however, if one mounts the Sigma 30mm f1.4 onto the SD1, thus creating equal opportunities (as much as this is even possible with such different cameras) and let them compete against each other
The SD1 with the 30mm f1.4 thanks to its wider aperture lets you manipulate DoF better. An advantage which results from the size of both setups. With an equal sensor, a 30mm f1.4 could never fit onto a hypothetical DP. That’s something you come across frequently in forums: “only f2.8”. Most critics, however, don’t realize how large the 30mm f1.4 actually is. It is much wider and thicker than the DP2m. A DP with a lens mount would have exactly the same problem. Fast lenses that are able to illuminate an APS-C sensor are simply too large to make sense on such a small camera. Laws of physics cannot simply be turned off.
SD1 and 30mm f1.4 above, DP2m below – same goes for the crops
The 30mm f2.8 is a more conservative design that is better optimized for wide open sharpness. It is to be expected that the slower lens will have a clear advantage in this test. But what if both lenses are stopped down to the “sweet spot” aperture of f5.6?
Again, the small 30mm f2.8 has the better head-to-head record. A rather unexpected result, keeping in mind the immense size difference. There is a reason the slightly modified design is so popular with NEX-users. I’m surprised every single time I view the DP2m photos at 100%. It’s simply unbelievable how much Sigma was able to squeeze out of such a small lens.
As soon as I have more time, I will head out with my tripod and both cameras. What particularly strikes me in this test is the fact that the 30mm f2.8 has a slightly wider angle of view than the f1.4. I cannot tell whether the former has a wider angle of view than stated or the latter a narrower than stated.