GH2 Noise and dynamic range above 66 Mbps for GH2

[rc444]

Hi Everyone,

Referencing a recent post (GH2 vs NIkon d5100), I studied both links LPowell wrote from PersonalView.Com. I noticed LPowell you took a video of a tree and said that even at 66 mb/s that wasn't enough to conceal the high noise of the GH2 when compared to the d5100 footage of the tree. At the conclusion of this comparison, you said an unhacked GH2 won't have the same low noise/high dynamic range as the d5100, but above 66 mpbs, you said that the hacked GH2 is in a class on its own.

Notwithstanding the noted noise issue of the un-hacked GH2 (as compared above), providing you filmed on a hacked GH2 *above* 66 Mbps, would this alleviate the noise/lower range? Would the noise and dynamic range be better than the Nikon if the GH2 was above 66 Mbps? Or, will the GH2, when compared to D-SLRs, always have the same noise/lower DR regardless of whether hacked or un-hacked?

 

[Lpowell]

When we discuss bitrates such as 66Mbps, we're referring to the amount of data that a camera's AVCHD encoder produces when compressing the frames scanned from the image sensor. Up to a point, the more data the encoder uses, the more finely it is able to preserve the detailed motion in the video. However, the Panasonic GH2 and the Nikon D5100 use very different types of AVCHD encoders, and it's not valid to rate them simply by the amount of data they produce.

A camera's dynamic range and noise level are primarily determined by the image sensor itself, though noise can be concealed in consumer cameras through the use of aggressive filtering. Both noise and DR are also affected by the ISO setting you use, with the lowest ISO's inherently producing the widest dynamic range. Sensorgen measured the noise levels of the GH2 and D7000 (same sensor as the D5100) across their ISO ranges and posted their results here:

http://www.sensorgen.info/PanasonicDMC_GH2.html

http://www.sensorgen.info/NikonD7000.html

In Sensorgen's tables, the column labeled "DR (stops)" is a rating of the dynamic range of each camera at the measured ISO. "Read Noise" is the amount of noise generated by the sensor. At ISO 100, the D7000/D5100 has a remarkable DR of 14 stops, compared to the GH2's 11 stops at ISO 160. Because of this massive head-start, the D5100 maintains a DR of 8.5 stops at ISO 3200, compared to the GH2's 7.2 stops. That's what gives the D5100 its low-noise advantage over the GH2 at high ISO's.