The 18Mp CCD previously used in Leica M rangefinders hasn’t fared well in our tests ranking towards the bottom for full frame sensors. The new 24Mp CMOS model is a big improvement however boasting 6 million more pixels than its predecessor and delivering a 1 Stop improvement in image quality, too. With a +1 Stop improvement for both Color Depth and ISO, as well as an impressive +1.6 Stops better Dynamic Range, it seems switching to a CMOS sensor was certainly a good move for Leica. It’s interesting to note too that no RAW smoothing is applied to files from the new model, as was previously the case from ISO 400 on earlier versions.
Two of the best full frame sensors we’ve tested in the fixed lens Sony RX1 and Nikon D800 DSLR offer a +2/3rds of a Stop image quality overall compared to the Leica M. Drill down into the different categories and the superior RX1 and D800 sensors deliver + 2/3rds of a Stop better Color Depth and Low-Light ISO performance. The Leica M’s measured base ISO of 134 compared to ISO 81 and ISO 74 for the RX1 and D800 respectively mean the Sony and Nikon cameras have an immediate advantage and deliver +1 Stop improved Dynamic Range overall with scores of 14.3 (RX1), 14.4 Evs (D800) and 13.3Evs (M). As sensitivity is increased on all three cameras Dynamic Range drops at roughly the same trajectory up to ISO800 where the Leica M takes a further dip. The impact of this is good Dynamic Range of 10Evs and over is only achievable on Leica M up to ISO1600, while the RX1 / D800 are good until ISO 3200 and these better sensors offer the same Dynamic Range at ISO 25600 as Leica M at its maximum sensitivity of ISO 6400.
Compared to the full frame sensor in Canon’s flagship DSLR, the 1Dx, the Leica M just wins overall with 84 points to 82. For Color Depth there’s little in it with 24 bits for the M compared to 23.8 bits for the 1Dx, so it’s left to Dynamic Range and Low-light ISO to separate them. At base ISO sensitivities the Leica M offers significantly improved Dynamic Range +1.5 Stop better than the 1Dx, although this changes quickly as sensitivity is increased.
While the 1Dx delivers consistently good Dynamic Range of around 11.8Evs up to ISO 800 the Leica M performance drops markedly as sensitivity is increased and by ISO 800 the two cameras are the same. The trend persists past ISO 800 too where the Leica M’s Color Sensitivity continues to drop rapidly and the 1Dx offers better Dynamic Range at ISO 25600 than the Leica M at ISO 6400.
Nikon’s top end DSLR the D4 ranks 1/3rd Stop better than the Leica M overall scoring 89 points compared to 84. The D4 is also ½ Stop better for Color Sensitivity at base ISO with 24.7 bits to 24 bits, but as the Leica M’s performance takes a dip as ISO sensitivity is increased the D4 offers +2/3rds of a Stop Color Sensitivity at ISO 1600 compared to the Leica M at the same sensitivity. While the D4 and the Leica M have similar Dynamic Range at base ISO sensitivity of 13.3Evs (M) to 13.1Evs (D4) the same pattern emerges as sensitivity is increased, so while good Dynamic Range of +10Evs is possible on the Leica M up to around ISO 800 the D4 delivers the same results up to ISO 3200.
No doubt you’ve picked up on the pattern here that while the Leica M can deliver comparable results at base ISO it struggles at higher sensitivities. With a DxOMark Low-light ISO score of 1860 ISO (M) compared to 2965 ISO (D4) and 2786 ISO (1Dx) the rangefinder offers around -1 Stop ISO performance compared to these flagship DSLRs.