The Sigma DP3M is the third camera in the DP Merrill range. While the DP1M and DP2M were designed to cover the wide-angle and standard ranges respectively, the DP3M features a high-performance 50mm F2.8 lens (equivalent to 75mm on a 35mm SLR camera) is meant for mid-telephoto, portrait and macro photography.
Externally, the DP3M is almost identical to the DP1M & DP2M. The most obvious physical differences are the significantly larger lens and the lens cap which is now similar to that of the 35mm f/1.4 lens.
Internal features that are new to the DP3M according to Sigma are:
(a) A unique, dual, Three-layer Responsive Ultimate Engine (TRUE) II image processing engine, which is dedicated to Foveon X3 direct image sensors to improve the processing speed and overall quality of the final image, and provide high-resolution power
(b) Special Low Dispersion (SLD) glass and aspherical lens elements are used to compensate for optical and chromatic aberrations and to allow for a more compact size
(c) A minimum focusing distance of 22.6cm and a maximum magnification ratio of 1:3 is achieveable for true macro capability
(d) Besides the standard 9-point select mode, there is a 'free move mode' which allows the selection of the desired focus point anywhere in the frame. Also new to the DP3M is Face Detection AF which prioritises focus on the face of the subject when detected by the sensor
So, with these additional features, how does the DP3M compare with the DP1M/DP2M in actual use.
First, the DP3M is supposed to have 2 of the TRUE II image-processing chips built-in to improves the processing speed and quality of the final image. But when I compare the processing and writing speed of the DP2M and DP3M by simultaneously pressing the shutter buttons of both cameras and visually comparing how long each camera took to process their respective shots, the DP3M is only milli-seconds faster than the DP2M. The difference is not really statistically significant.
As for focussing, the DP3M has a new focusing engine that is more complicated and user-customisable than those of the DP1M and DP2M. The DP3M does not however seem to focus any faster than the DP1M and DP2M though.
What the DP3M does have is more options for the AF Limit Mode. The menu for AF Limit mode is as shown in the pic below.
There is now Macro (0.226m - 1.0m), Portrait (0.35m - infinity), Landscape/Snap shooting (default) (1m - infinity), and Custom AF Limit. The DP1M & DP2M also have an AF Limit Mode but they are limited to a choice of only the Landscape/Snap shooting mode.
The AF speed of the DP3M can actually be slower than the DP1M/DP2M if the camera has been set to an AF Limit mode that is inappropriate for the subject distance required.
Since the DP3M is meant for macro, portrait and mid-telephoto shooting, so how is its performance in these areas?
I tested its macro-photography capability by shooting a $2 note close-up at around the minimum focussing distance of 22.6cm at aperture settings of f/2.8 (wide opened) and stopped down to f/8.
Macro Close-up of $2 Note at F/8.0
Macro Close-up of $2 Note at F/2.8
Looks like it is a very sharp macro lens without any observeable colour fringing. At f/2.8, the top left and right corners are just slightly soft compared to those at f/8.0.
And here's the first portrait shot taken wide-opened at f/2.8 from the DP3M, but it is a portrait of one of my cats though.
1/100s f/2.8 at 50.0mm ISO 100