It may push the definition of ‘compact’ to its limit, but Leica’s top-end CSC has some outstanding features that set it apart from the rest, as Andy Westlake discovers
Leica SL (Typ 601) review – Image quality
Leica has fitted the SL with a 24-million-pixel full-frame CMOS sensor, which it says is related to that inside the Leica Q (Typ 116) full-frame compact, and is not the Sony unit used in several other full-frame cameras. Specifically, the design of its pixels means that they can accept incoming light from more acute angles, which according to Leica means it should be less prone to the colour shading and corner smearing that can be seen when shooting with certain M-mount wideangle lenses.
With no low-pass filter, the sensor resolves a lot of detail, although this means it can occasionally be prone to giving image artefacts in return. As we’d expect from a modern full-frame sensor, low ISO dynamic range is very high, and high ISO noise performance very commendable, too.
At low ISOs of 50-200, the SL gives an impressively high dynamic range of 12.5EV or more in our Applied Imaging tests, indicating that raw files should offer significant scope for manipulation and recovering shadow detail in particular. Beyond ISO 400, it starts to fall more rapidly, and by the time we get beyond ISO 3,200 it’s rather low, indicating that at this point noise will start to have a more serious impact on detail. At ISOs 25,000 and 50,000 we see very low readings, suggesting these settings should be avoided.
With a measured resolution at ISO 50 of almost 4,000l/ph, the SL gets about as much out of its 24-million-pixel sensor as theoretically possible. This also confirms that the 24-90mm zoom is impressively sharp; we shot these tests at 50mm and f/5.6. Stepping up through the ISO range sees resolution slowly diminish due to the effects of noise, but it’s still around 3,600l/ph at ISO 1,600, and 3,400l/ph at ISO 6,400. Beyond this, things take a turn for the worse, with noise limiting resolution to 2,800l/ph at the highest setting.
Both raw and JPEG images taken from our diorama scene are captured at the full range of ISO settings. The camera is placed in its default setting for JPEG images. Raw images are sharpened and noise reduction applied, to strike the best balance between resolution and noise.
With beautifully clean and detailed images, the Leica SL gives excellent results at low ISO settings. In normally processed images, it maintains near-indistinguishable image quality at ISO 1,600, with just a little noise creeping into shadow regions if you examine images very closely at the pixel level. ISO 3,200, however, is still very good indeed, and it’s only at ISO 6,400 that fine details start to get visibly blurred by the impact of noise. Step up to ISO 12,500, though, and things start to deteriorate more quickly; low-frequency colour botching is detectable in shadow regions, and fine low-contrast detail is beginning to get overwhelmed by noise. Even so, this setting should be acceptable for small prints or web use. The top two sensitivities, in contrast, really aren’t very good at all, and should be reserved for situations where there’s no other option.