Weather-Sealed Mirrorless Image-Quality

When it comes to image-quality, the latest generation of mirrorless cameras delivers in accordance their sensor-size. They generally perform quite well at the base sensitivity with noise appearing only beyond a certain ISO and steadily increasing from there. Sharpness is mostly limited by the lens in use until it gets clipped by the anti-alias sensor present on some models.

The Fuji X-T1, XT-1 Graphite and Olympus E-M1 all skip the anti-alias filter to maximize captured details given a sufficiently sharp lens. Fuji cameras use a unique 6x6 color-filter-array which prevents the appearance of moire despite their lack of an anti-alias filter. Olympus and Panasonic use a traditional 2x2 Bayer color-filter-array which makes moire artifacts more likely on the E-M1.

All these weather-sealed mirrorless cameras other than the Nikon 1 AW1 have native sensitivity of ISO 200. These allow an expanded Low ISO of 100 too. The AW1 has a native ISO 160 sensitivity with no expansion option. Expanded ISO allow to perform different exposures but reduce dynamic-range. Compare the base sensitivity:

Fuji X-T1 Graphite - ISO 100	Nikon 1 AW1- ISO 160
Olympus OM-D E-M1 - ISO 100	Olympus OM-D E-M5 Mark II - ISO 100
Panasonic Lumix DMC-GH4 - ISO 100	Panasonic Lumix DMC-GX8 - ISO 100

The Fuji X-T1 clearly delivers the smoothest output. It also shows top sharpness along with the Olympus E-M1, as expected, since those are all the anti-alias filter-free cameras. The Olympus E-M5 Mark II shows the next best output, with very slightly more noise and a tiny amount of softness. Both Panasonic are quite similar with a little more softness on the GX8 which cancels its resolution advantage. Unsurprisingly, the AW1 is one step behind with visibly soft output.

The next ISO sensitivities show slightly more noise yet preserve details well. Although the output looks different when viewed at 100%, print sizes are minimally affected until ISO 800. Here is what it looks like:

Fuji X-T1 Graphite - ISO 800	Nikon 1 AW1- ISO 800
Olympus OM-D E-M1 - ISO 800	Olympus OM-D E-M5 Mark II - ISO 800
Panasonic Lumix DMC-GH4 - ISO 800	Panasonic Lumix DMC-GX8 - ISO 800

The smoothness of the X-T1 is amazing. This is partly due to noise-reduction which cannot be turned completely off yet retains fine details extremely well. Comparatively, the E-M1 is more hands-off and leaves a tad more noise while keeping critical sharpness. Just as before, the E-M5 Mark II follows, then the Panasonic GH4 and GX8, leaving the AW1 where it is.

Now going to ISO 6400, the maximum sensitivity of the Nikon 1 AW1, noise increases significantly. All digital cameras respond with stronger noise-reduction. Regardless, maximum print sizes are notably affected. This is what ISO 6400 looks like on each camera:

Fuji X-T1 Graphite - ISO 6400	Nikon 1 AW1- ISO 6400
Olympus OM-D E-M1 - ISO 6400	Olympus OM-D E-M5 Mark II - ISO 6400
Panasonic Lumix DMC-GH4 - ISO 6400	Panasonic Lumix DMC-GX8 - ISO 6400

At ISO 6400, there is no longer a clear winner between the X-T1 and E-M1. They simply use a completely difference balance between noise and details. The E-M5 Mark II is slightly noisier than the E-M1. Panasonic pushes noise-reduction even further than Fuji, producing smooth images with fine details erased. Although it shows more noise and softness, the AW1 holds together quite nicely, considering its sensor is that much smaller.

Fuji X-T1 Graphite - ISO 25600	ISO 25600 is the torture test. Here the Fuji X-T1 easily takes back the lead and is the only one to deliver usable prints beyond the smallest size. Both the Olympus E-M1 and Panasonic GX8 turn in a decent performance though. Knowing that the APS-C sensor in the Fuji is larger than Micro Four-Thirds, its lead is expected. Still, Micro Four-Thirds really delivers on image-quality.
Olympus OM-D E-M1 - ISO 25600	Olympus OM-D E-M5 Mark II - ISO 25600
Panasonic Lumix DMC-GH4 - ISO 25600	Panasonic Lumix DMC-GX8 - ISO 25600

With dynamic-range, the larger APS-C sensor has a more dramatic edge over Micro Four-Thirds which, in turns, is significantly ahead of the 1" sensor in the Nikon. Fuji keeps the dynamic-range lead until ISO 6400. Things even out beyond that as noise turns blacks into grey.

Color rendition is flexible on most of these weatherproof mirrorless cameras. One can also render differently from RAW but the one which nails them in-camera is again the Fuji X-T1. There is too much red in the Olympus and Nikon, while the Panasonic cameras slightly exaggerate green. The GX8 manages to follow closely behind the Fuji.

This set of cameras offers some of the most reliable metering. Only the E-M1 produces a little more over-exposure than the rest. Of course, given its wider dynamic-range, the X-T1 has an easier job. Still, the Panasonic GX8 seriously challenges the Fuji.

When it comes to autofocus, Panasonic has the clear winners. The GX8 and GH4 have ultra-fast AF systems with class-leading sensitivity. They focus exceptionally fast and show an even greater lead in low-light. The Fuji and Nikon focus very quickly too but both slow down considerably when light is low.

All these cameras are quite responsive. Shutter-lag is nearly instant while black-out time is around ¼s for all but the GH4 and AW1 which are both slower. The fastest shot-to-shot speeds come from the GH4 and GX8, followed closely by the E-M1. The E-M5 Mark II and X-T1 are a little slower, while the AW1 trails far behind, despite having the fastest continuous drive.