Panasonic GH2 vs. Sony NEX-7 : comparaison vidéo

Voici un test comparatif du rendu en vidéo des Panasonic GH2 et Sony NEX-7. Ce test nous est proposé par Hacky qui a pour cela utilisé un GH2 avec un firmware 1.1 officiel, un GH2 hacké et donc un Sony NEX-7.

It’s time for a closer look at the video quality of Sony’s new NEX-7 by comparing it to the current flagship of the MicroFourTHirds (mFT) system cameras, the Panasonic Lumix GH2.

In order to compare it to a GH2 with current V1.1 firmware as well as to a GH2 with a patched V1.0 firmware, three cameras were taken to a side-by-side video shootout.

Important note:
The Vimeo video that you find embedded here is NOT applicable to judge the quality of the ouput of these cameras due to the fact that the original FullHD 1080p video was rendered with 28 Mbps to 25 frames per second (fps) and the video that Vimeo streams is re-rendered by Vimeo at about 4.5 Mbps. As a result, you will see a video with less details and a lot more artifacts. So, to get a realistic impression, you will have to download the master file that was originally rendered and uploaded to Vimeo. If you are a registered Vimeo user, you find a download link on the Vimeo video page (please right click that link and select « Save to… » in order to download that file). This resolution and this high frame rate requires very powerful ressources from your playback equipment. Only systems that support hardware H.264 decoding on their graphics card will be able to play it without judder. The MediaPlayer included in Windows 7 supports many hardware accelerations of today’s graphic cards, so chances are good with that player. VLC’s support for H.264 hardware decoding are still experimental and must be explicitely activated in the VLC player’s settings. If you have very powerful ressources you may try the 1080p 50 fps @ 32 Mbps version as well, that you find here: http://vimeo.com/35823620 (but please also download the source file, as the Vimeo rendering to 30 fps is awfully choppy with a lot of judder). For the sequences that were recorded initially in 25fps, the 25 fps version is fairly enough, only the 50 fps sequences loose some information accordingly.

Regarding the content itself:
There were three cameras used, one NEX-7 with Voigtlander Nokton ASPH 35mm/F1.2 (adapted with a Novoflex adapter), two Panasonic Lumix with Leica GH2 25mm/F1.4 DG ASPH. The focal lengths resulting from the sensor crop factors have a fullframe equivalent focal length of about 53mm compared to 50mm but the different area used for 16:9 videos on the multi format sensor of the GH2 seems to result in a different crop factor. One GH2 contained the current firmware version 1.1 with the new « high bitrate » mode (1080p25 @ 24 Mbps), the other one contained a hacked V1.0 firmware with a patch for the 32 Mbps 1080p24 mode. There are three sequences in which each time the NEX-7 is compared with one of the GH2s mounted side-by-side on a tripod. The cameras were set to default contrast, sharpness and film mode at basi ISO (160 for the GH2, 100 for the NEX-7), white balance was set to AWB.

In the first sequence the 720p50 mode of the GH2 (V1.1 with 17 Mbps) is compared to the 1080p50 mode of the NEX-7. The section of the GH2 video was subsequently scaled up to 1080 lines. The shutter speed was set to 1/100s. The second half of the sequence contains a relatively swift swing as panning for the passing barge, which clearly benefited from the higher frame rate. The aperture was set at F5.0 on the GH2 and to about F4.5 at the NEX (due to its lower ISO sensitivity).

In the second sequence the 1080p25 modes (each camera with 24 Mbps) are compared. The shutter was set to 1/50s, aperture F7.1 at the GH2 and appxoximately F6.3 at the NEX-7.

In the third sequence the 24p cinema mode of the GH2 (V1.0 with a « mild » 32 Mbps patch) is compared to the 1080p25 mode of the NEX-7 (24 Mbps). The 24p video is sped up by 4% in order to preserve a smooth rendering without the sporadic inserted frame repetitions when rendering at 25 fps or 50 fps. The two sequences were cut to one another such that, in the middle part they are in about the same time.

Please follow to the full article at http://3d-kraft.com/index.php?option=com_content&view=article&id=111:nex-7-vs-gh2-side-by-side-comparison&catid=40:camerasandlenses&Itemid=2

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