Testing my GH2's sensor

Started Feb 20, 2011 | Discussions thread
kenw Veteran Member • Posts: 5,350
Re: Testing my GH2's sensor

BillHinge wrote:

So a test would be shoot a dark scene at ISO 3200, do same scene with same shutter and aperture but dial in 2 stops under exposure compensation

The compare and contrast in LR and the 2 stops under exposure will look better once corrected ?

I think the assertion is shoot the same scene at ISO3200 properly exposed and at ISO800 underexposed by two stops (so the two shots will have the same aperture and shutter speed), then take both into LR and add 2 stops of exposure compensation to the underexposed ISO800 shot and the results should look the same as far as noise goes.

The ISO800 is only potentially "better" in that if the scene had very bright highlights you could still do something with them where as in the ISO3200 shot they would have been blown/clipped. This is a fairly common phenomenon with the highest ISO settings of many cameras, the in camera ISO gain really doesn't improve the RAW data in anyway and is more of a convenience for JPEG and RAW processing.

Keep in mind though, sometimes in LR and other RAW converters you'll see other effects when doing large exposure compensation. The color processing isn't quite as "linear" you'd expect and you may see a slightly different rendering of certain colors between the two shots. This has nothing to do with the sensor, but just with the order in which LR applies various color transformations relative to the exposure compensation. It only happens with certain camera profiles in LR/ACR and is usually subtle.
Ken W

Rebel XT, XTi, Pany G1, LX3, FZ28, Fuji F30, and a lot of 35mm and 4x5 sitting in the closet...

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