The Panasonic Lumix DMC-GX8 may be the first Micro Four Thirds camera to sport a 20.3-million-pixel sensor, but it has a whole host of other updates too. Andy Westlake takes it for a spin
Panasonic Lumix DMC GX8 review: Image quality
With its new 20.3-million-pixel sensor, the GX8 brings a useful advance in image quality compared to previous Panasonic models. The expected boost in resolution is welcome, if not exactly groundbreaking, and high ISO noise seems slightly reduced, with ISO 3,200 very usable where on previous cameras it was a bit marginal. There also appears to be some improvement to low ISO dynamic range. I found that it’s possible to pull about 3 stops of detail out of shadow regions before noise becomes problematic, although you’ll need to use a touch of chroma noise reduction even at ISO 200. These individual improvements aren’t necessarily huge, but together they help close the gap relative to the current generation of 24-million-pixel APS-C DSLRs, and it means that the GX8 has the best raw image quality of any Micro Four Thirds camera yet.
With resolution closing in on 3,600l/ph at ISO 100 (shot using the Olympus 60mm f/2.8 Macro lens at f/5.6), the GX8 squeezes about as much out of its 20.3-million-pixel sensor as it could possibly get. Resolution inevitably drops slightly as ISO is increased, and noise with it, but at ISO 1,600 it’s still around 3200l/ph, which in context is similar to the 16-million-pixel G7 at ISO 200. Thereafter, it falls more precipitously, especially at the top two sensitivities, giving just 2,300l/ph at ISO 25,600.
The GX8 produces creditable results in our Applied Imaging tests, giving somewhat improved results compared to the G7 we tested recently, although still a little behind APS-C cameras like the Canon EOS M3. A dynamic range of 11.6EV at ISO 100 indicates plenty of leeway for recovering shadow detail, and even at ISO 1,600 we get a respectable reading of 9.4EV. However, the numbers fall monotonously after this, with very low readings at ISO sensitivities of 12,800 and 25,600.
ISO sensitivity and noise
At low sensitivities of ISO 100-400, the GX8 gives sharp, detailed images with bright colours and little visible noise. At ISO 800 noise starts to become obvious in raw files, but Panasonic’s JPEG processing smooths it away quite aggressively, with some impact on fine detail. By ISO 3,200 fine detail has mostly disappeared from JPEGs, and shadow detail has become indistinct, although more can be extracted from raw files. ISO 6,400 is just about usable at a pinch, but the JPEG files show low-frequency colour blotching in the shadows and barely any fine detail at all – shooting in raw and applying your own preferred noise reduction is highly advisable here. Step up to ISO 12,800 and things deteriorate further, although it might be OK for small prints or low-resolution web display. However, the top sensitivity of ISO 25,600 is best avoided.