The Panasonic GH6 uses a new 25MP Four Thirds sensor we've not seen before. It offers a Dual Output Gain mode that implies it's using a different physical design compared with most of the chips we encounter. This, combined with Panasonic's briefing, points to the use of a different sensor maker, for what we have reason to believe is a non-stacked BSI chip.

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It's this move to a different design and supplier that is likely to have the biggest impact (positive or negative) on its performance, relative to its peers, rather than the increase in pixel count. We've seen it does a great job of reading out quickly, and we've seen its additional highlight capture at higher ISOs in video mode, but how does it perform for stills, and should we be hoping to see this same chip in a hypothetical G9 successor?

Studio Scene

Our test scene is designed to simulate a variety of textures, colors and detail types you'll encounter in the real world. It also has two illumination modes to see the effect of different lighting conditions.

Looking at the GH6's detail levels, they're essentially impossible to distinguish from its 20MP peers (which is to be expected, given the move to 25MP is an increase of just 11% in linear resolution). Even this small increase in resolution is risked because the rather disappointing magnified live view on the GH6 makes fine focus extremely difficult.

In terms of noise, the new sensor performs comparably with the one in the G9. This means it falls a little behind the chip in the OM-1 at very high ISOs, but there's no obvious downside for the change in sensor maker or design.

JPEG detail is very good, with subtle sharpening bringing out, but not over-emphasizing, fine detail, meaning that fine natural textures are convincingly represented.

Default JPEG color looks good. There's a hint of magenta to the central pink patch and a hint of green to the yellow, but both are subtle enough that we'd want to check whether they have any impact on real-world images.

Noise levels are well controlled at higher ISOs but that comes at the cost of detail and texture being lost to noise reduction. Overall, it performs very similarly to its immediate peers.

The 100MP pixel shift high resolution mode looks very good, even when downsized back to a lower resolution. The multi-shot nature brings the expected improvement in noise and tonal quality you'd expect of multiple sampling. Sadly the stills mode we're most excited by (the first hand-held high res mode with motion correction) can't be shot using our studio tripod setup, so will need to wait for additional outdoor testing.

Dynamic Range

Our Exposure Latitude test delves into the deep shadows of base ISO images to test the degree to which you can underexpose to protect highlights, then exploit the camera's full dynamic range. The GH6 is showing significantly more noise when given the same exposure as the OM-1. In principle this represents deeper shadows because of the difference in their respective base ISOs, but the difference is pronounced enough that you can comfortably conclude that the GH6 has less usable dynamic range than the OM-1.

The ISO invariance tells a similar story: above ISO 800, where the GH6's Dual Output Gain system kicks in, the two camera look very similar, but push the lower ISOs and the Panasonic shows increasing noise levels in the very deep shadows. This suggests you should probably raise the ISO on the Panasonic, when shooting in low light, at least until you get to ISO 800. Above that point, you can keep ISO pinned at 800, underexpose and brighten in post, if you want to include extra highlights in your image.

The GH6's dual output gain is one of the few times where there might be a significant change in dynamic range in the highlights. However, unlike in video mode, we're not seeing an extra stop of highlight capture in the stills we've shot, so it could be that stills mode is set up differently, to give a shadow benefit instead of additional highlights. We'll look more closely at this as we shoot more with the camera.