The resolution of the GX7 sensor has been tested on the basis of RAW files, not just on the basis of out-of-camera jpegs, and has been found to be roughly on a par with that of other micro four thirds cameras with 16 MP sensors. See the results from optycne.pl here, for example.
There is simply no way your results could be as far out of line as they actually are (worse than for the G1, the very first MFT camera with 12 MP sensor) unless a) you made some mistake in your testing or b) tested a faulty unit.
Note that some MFT cameras have problems with so-called "shutter shock" (blur induced by shutter action) in certain shutter-speed ranges and that this problem might potentially affect individual copies of a certain camera more than other copies of the same camera (e.g., because some component is not fixed in a perfectly rigid manner). Note also that some MFT cameras, including the GX7, have electronic shutters that should normally let you bypass any blur-related problems caused by the mechanical shutter.
When you tested the GX7: Did you use the mechanical shutter or the electronic one?
Thanks for your feedback. The lens results using the Panasonic GX7 are indeed surprising. Optyczne.pl is a very good website and their reviews are great.
For the Panasonic GX7, the tests were performed on one camera body, loaned by Panasonic. It is very unusual to have sample variation between cameras these days but we will perform more tests on another camera sample in early January. (The lab will be closed between Christmas and New Year’s Day).
We are aware of the possible vibration problem produced by a mechanical shutter.
The following describes our procedure for shooting Through Focus MTF Targets. For each measured focal length and aperture setting:
- Distance set to 35x the focal length
- Camera is positioned in the middle of a focusing rack; autofocus is initiated to test accuracy (in live view mode if possible)
- Autofocus switched OFF
- We then perform more than 40 shots on a long focusing rack, bracketing around the focus distance to find the optimal focusing position (without using autofocus). With this step, called “through focus”, we are 100% certain to locate and record the optimum or “best focus” position for each lens, when mounted on the camera.
There are many sources of vibration that could impact sharpness / resolution measurement (i.e. mechanical shutter, mirror for vibration, tripod-type used etc …)
- To avoid problems arising from vibration we use a very specific protocol:
· Lab is in perfect darkness
· Heavy (72 kg) studio stand
· Remote control is used
· Step 1: mirror lock where possible
· Step 2: Timer: 2s
· Step 3: Time exposure 1s in total dark in order to get rid of the shutter vibrations
· Flash between 1/4000s and 1/1000s depending on the aperture, synchronized on the second curtain
· Electronic shutter where possible
The DxOMark team