246 Shades of Grey: Leica M Monochrom Typ 246 real-world and studio samples
The sensor in the Leica M Monochrom (Typ 246) is an interesting one. Without a color filter array, the 24MP CMOS sensor doesn't lose sharpness through interpolation, much like a Merrill-generation Foveon sensor or Pentax's pixel shift mode found in the K-3 II. The catch is, of course, no color. However, it also means the sensor is more... well... sensitive at base ISO, making this ones' base ISO 320 instead of 200 like its Bayer counterparts.
There is another issue, however. Even without a mirror flipping out of the way in this rangefinder, the shutter causes blur at speeds near 1/125sec when using the 90mm F2 Summicron, which has been identified as a symptom of the camera being set to its default "advanced" metering mode, which has the shutter open constantly for metering. The camera then has to re-close the shutter and re-open it to expose, causing the blur. To see the true sharpness of the camera at base ISO in our studio scene, we have set our default to low-light mode where the shutter's effect isn't present.
We will try to get the camera back to re-shoot in "classic" metering mode.
You'll notice that the M Monochrom is marked as non-standard. Keeping true to its rangefinder roots, it can only change shutter speed in half-stop increments, whereas our standardized Raw exposures are based off of third-stop increments.
However, the M does do exposure compensation in third-stops, even though it will only report half-stops. Therefore we shot the M in aperture priority and bracketed +-1 stop EV. We then, since it didn't report accurate shutter speeds in its metadata, chose the Raw exposure that was closest to Lab 50 without adjustments. JPEG images still follow our normal procedure.