Panasonic GX80/85 User review Part 2 Image Quality and Performance

GX85 with 12-60mm at 35mm

Image Quality

The main determinants of image quality are the sensor, processor,  lens and other factors in use such as image stabiliser.  The GX80/85 appears to use the same basic sensor as the GX7 but with the anti aliasing (AA, a.k.a. OLPF) filter removed for a small increase in resolution.

This sensor is no bad thing and in fact makes very good pictures but there appears to be a significant pause in sensor development in the micro four thirds sector. 

The GH4, G7, GX7 and GX80 all appear to use the same or very similar 16 Mpx sensor which has now been around for about three years.

Sure, that is not very long but the smaller Sony ‘One inch’ sensor which now appears in many fixed lens cameras from Sony, Canon and Panasonic has more pixels and about the same DXO Mark score.

For instance the GX85 scores 71, the RX100 Mk4 scores 70, virtually the same.  The GX85 has about one EV step less noise at ISO 6400 but at low ISO settings the smaller Sony sensor has a slight advantage.

Panasonic claims that the GX85 has  “almost 10%” better resolution than the GX7 and my tests tend to support this claim, with resolution from the GX85 being so close to that of the 20Mpx GX8 that I really cannot pick the difference.

I also found no evidence of increased moire or other artefacts resulting from the lack of  an AA filter.

Otherwise the GX85 has about the same image quality as the GX7 and other recent 16 Mpx M43 cameras.

The new mechanical shutter makes an important contribution to image quality. It has not thus far been shown to cause shutter shock. Therefore the mechanical shutter can be used all the time. 

Compare this to the G7 for instance which has a shutter which does cause shutter shock requiring use of the E-Shutter with some lenses. But this drops output from 12 bits per channel to 10 bits with a deleterious effect on image quality particularly in dark tones lifted in Photoshop or other image processor.

So although the image quality story is largely 16 Mpx-business-as-usual the addition of the new shutter, removal of the AA filter and the contribution of Dual IS all work together to help the user to make slightly better pictures than was possible with previous 16Mpx models.

Performance

The GX85 is a very fast, responsive camera in every respect.

For the performance tests I used a San Disk 95 MB/Sec card.

Using AF Single,  Drive Mode Single and pressing the shutter for AF + AE on every shot, I made 10 shots in 3 seconds which gives a shot-to-shot time of about 0.3 seconds which I regard as excellent.

Using AF Continuous, Burst M Drive and JPG capture  the camera fired 53 frames in 10 seconds for a rate of  5.3 frames per second with AF on each frame. There was no delay clearing the buffer with JPG capture.

When I switched to RAW+JPG, the camera shot 46 frames in 10 seconds (4.6 fps) before slowing down.  The buffer then took 35 seconds to clear.

The camera continued to work while writing to the card.

With AF single I found focus speed and accuracy to be excellent in all conditions.  AF acquisition is so fast it is almost instantaneous in most conditions with most lenses.

In very low light, so dark I can barely see, the camera switches to low light mode and will slowly (by which I mean it can take a second or so) but surely acquire accurate focus.  The AF assist light is not required.

The camera responds to all user inputs promptly with no delays.

With a suitable lens (DFD compatible) the camera can  hold focus on a moving subject using 1 Area AF,  AFC and burst M.

Summary

The GX85 delivers very good image quality and performance in almost any circumstance.

It offers small but useful upgrades over previous M43 models including the more expensive GX8 which lacks the new electro mechanical shutter and 5 axis IBIS.

However when I use the GX85 I have the sense that this is a camera-in-waiting for the next big thing  whatever that may be.

There are some obvious candidates, including a significant increase in sensor performance, a global shutter and high level DSLR standard predictive autofocus.

We shall see, but I think the M43 product development people need to come up with significant developments sooner rather than later.

I have recently been using the Sony RX100 (4) compact camera alongside the GX85 with 12-60mm lens. I am finding that I have to enlarge test frames to 200% on screen to detect any difference between them, which  by the way is slightly in favour of the Panasonic combination and then mainly in the corners. But you would not pick this in everyday photography.

If I want to go out and about with a camera and not be overly burdened by equipment, I will usually take the little Sony or even the Panasonic TZ80 in preference to the GX85.