written by Ivo Freriks
published on 26 January 2012

Review Panasonic GH2: Measurements

 

While we're waiting for the introduction of the Panasonic GH3 and our soon forthcoming Panasonic G3 review, we tested the Panasonic GH2. This test report supplements our Panasonic GH2 review. The measurements were performed using Imatest.

For the test method and explanation of terms, see the FAQ section.

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Sensor resolution

raw-resolutie-panasonicgh2

 jpg-resolutie-panasonicgh2
The resolution of Panasonic GH2 jpg files is one of its strengths. The Panasonic GH2, combined with the Panasonic 14-140 kitlens @  32 mm stopped down at 7.1, yields a jpg file with a constant over the entire ISO range, average resolution of 1800 LW/PH. Standard developing of a RAW file in Lightroom yields a slightly better sharpness impression and a resolution of 2000 LW/PH.

Dynamic Range

The total dynamic range of micro-43 sensors is their Achilles heel at the moment. Panasonic doesn't tell whether the bit depth of the Panasonic GH2 sensor is 12 bits or 14 bits, but with their expensive video cameras they explicitly state they are 14 bits. We can therefore safely assume that the Panasonic GH2 sensor is 12 bits. No surprise then, that the total dynamic range is a little over 2 stops less than the total dynamic range of 14 bit sensors in Canon and Nikon cameras like the Canon 60D or Nikon D5100. The total dynamic range of the Panasonic GH2 is very constant over the entire ISO range and completely identical for jpg and RAW files: 9.2 stops on average over the entire ISO range.

For the test method and explanation of terms, see the FAQ section.

 dynamisch-bereik-panasonicgh2
Unfortunately, not all stops of the entire dynamic range are suitable for a nice picture. A poor signal to noise ratio (mostly in the shadows) reduces the dynamic range of jpg files to a usable dynamic range of 9 stops at lower ISO range down to 2  stops at 12.800 ISO. The 9 stops usable dynamic range seems a bit overestimated: during the field test for our Panasonic GH2 review we did find several low ISO files files with both blown out highlights and completely black dark areas.

Jpg files, because of in-camera noise reduction, seem to perform better than RAW files from ISO 400 and higher. Yet that is not true. We test the dynamic range of RAW files without using any noise reduction. By doing that, you maintain the highest possible detail in the recordings. The noise, although measurable, will not be visible in print. But if you carefully adjust contrast, sharpening and noise reduction for RAW files, it is possible obtain a usable dynamic range better or equal to that of the jpg files.

 usable-dynamic-range-panasonicgh2

Noise

Comparison of JPG files with RAW files (without any noise reduction) show that the noise of the jpg files is suppressed even at the lowest ISO levels. You will be able to print these  images at A3+ size. We know from experience that - regardless the camera a picture has been taken with -  whenever the noise is less than 2.5%, an A3+ photo print can be made without the noise as a disturbing factor.

 jpg-noise-panasonicgh2

Below sections of a gray card, photographed at different ISO settings, are shown. As mentioned earlier, we didn't use any form of noise reduction for the RAW files. By applying noise reduction to the RAW files even better results would have been achieved.

 raw-noise-panasonicgh2
noise-low-iso noise-high-iso-panasonic-gh2

Color accuracy: Daylight

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Color accuracy (Δ E 94) Panasonic GH2 @ daylight

  • Mean  9,5 (RAW) / 7,9 (jpg)
  • Best 4,1 RAW @ 160 ISO
  • Worst 15,8 RAW @ 12.800 ISO
  • Skin tones: 8,8 (RAW) / 7,7 (jpg)
  • Natural colors: 9,5 (RAW) / 8,2 (jpg)
  • Bright colors: 9,0 (RAW) / 8,1 (jpg)
  • White Balance: 5,8 (RAW) / 5,4 (jpg)

The Panasonic GH2 delivered RAW and jpg files with an average color rendition. Manual correction of the white balance will improve the color accuracy (shown below). On mouse over you'll see a larger version of the left picture.  For a brief description of the test method and explanation of terms, see the FAQ section.

Click on the image for a larger version.

Color accuracy @ tungsten light

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Color accuracy (Δ E 94) Panasonic GH2 at Tungsten light

  • Average 23 (RAW) / 25 (jpg)
  • Best 21 RAW @ 160 ISO
  • Worst 27 jpg @ 160 ISO
  • Skin tones: 19 (RAW) / 27 (jpg)
  • Natural colors: 25 (RAW) / 27 (jpg)
  • Bright colors: 17 (RAW) / 21 (jpg)
  • Whitebalance:

Click on the image for a larger version.

The auto whitebalance didn't do a very good job in tungsten light, both for RAW and jpg files, as can easily be seen from the image above (a 200 ISO jpg file). But correcting the whitebalance afterwards yielded files with an excellent color accuracy: mean Δ E 94= 4 and Δ C 94= 2.64!

This test report supplements our Panasonic GH2 review.

panasonicgh2-wbcorrected

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