Panasonic Lumix DMC-GX7 review – Noise, resolution and sensitivity
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using a Lumix G Vario 14-42 /f3.5-5.6 II -aperture set to f/8 focal length 25mm (equivalent of 50mm on a full-frame camera) . We show the section of the chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
This is by no means the first time we’ve seen a 16-million-pixel sensor in a Panasonic CSC, but as I’ve mentioned previously, the sensor in the GX7 is a completely new design that promises a number of improvements over previous incarnations.
It may not be quite a match for some rivals that offer 20-million-pixel-plus sensors, but it should strike a good balance between resolving power and noise considering the surface area size of the sensor.
In terms of detail, the GX7’s sensor is capable of resolving detail to just over 26 lines per mm (lpmm) on our chart at ISO 200, which compares favourably with APS-C-format rivals, though raw files allow more detail to be prised from them than JPEGs do.
The GX7’s standard ISO range of 200-25,600 offers photographers plenty of versatility, while the ability to shoot at an expanded ISO 125 is a welcome addition.
Inspecting JPEG files shows that the GX7’s sensor renders smooth, noise-free results until ISO 1600, where close examination reveals in-camera noise reduction has caused very fine detail to suffer, though image noise is barely evident. Raw files at the same ISO show a small amount of colour noise beginning to encroach but detail is still strong.
Increasing the sensitivity further shows that JPEG files at ISO 6400 still display well-controlled image noise. Colour noise is almost non-existent, while luminance noise is just beginning to creep into the image. However, in an attempt to subdue image noise, the GX7’s noise-reduction system has resulted in the loss of fine detail, with some areas becoming mushy in appearance.
Raw files at ISO 6400 display relatively pronounced colour noise but luminance noise remains reasonably fine, and while detail is not rendered quite as well as at ISO 200, it is still very good. There is currently no support for the GX7 in Adobe Camera Raw, but it is possible to reduce the effect of colour noise in the rather clunky Silkypix Developer Studio 3.1 SE, which comes bundled with the camera.
Image: Colour noise in JPEG files was almost non-existent, even at higher ISO sensitivities
