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GH1-GH3 compared at ISO 200

Started Dec 9, 2012 | Discussions thread
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Anders W
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Re: GH1-GH3 compared at ISO 200
In reply to Detail Man, Dec 13, 2012

Detail Man wrote:

Anders W wrote:

exdeejjjaaaa wrote:

Anders W wrote:

exdeejjjaaaa wrote:

switching extended ISO on/off in GH3 does not change anything for ISO200 raw shots histogram wise in RawDigger... saturation variations are around 1/12 or even less EV for all channels... which is honestly expected, such a trickery will be unprecedented in camera world.

Have been scrutinizing the EXIF data from the RAWs you uploaded in the other thread versus those, obtained from others sources, that I used for my "measured ISO" comparisons. One difference I noted apart from things we have already dicussed and tested, is that yours have Colorspace showing as "Uncalibrated" whereas those I have from elsewhere show "sRGB". I guess "Uncalibrated" here indicates Adobe RGB, particularly since your file names indicate to me that this is what you have the camera set to.

yes, as a part of my UniWB settings for GH3 (and other cameras before) I am using AdobeRGB for JPG (previews).

That is consistent with what I see in my GH2 image-file meta-data when Adobe RGB is selected.

Further, your RAWs have a tag for Gamma showing the value 2.2 whereas those I have from elsewhere simply do not have that tag at all. Possibly, the explanation is that this tag is used only if you choose Adobe RGB rather than sRGB, but that's just an idea. Both of these tags appear in the ExifIFD section when I view the EXIF by means of Exiftool GUI.

might be - I did not do anything else special... but AdobeRGB was indeed selected

That is consistent with what I see in my GH2 image-file meta-data when Adobe RGB is selected. There is no Gamma tag visible in ExifTool when sRGB is selected. sRGB Gamma correction constant equals 2.4 (with an offset at low input levels) - whereas Adobe RGB is Gamma=2.2 with no offset at low input levels.

My GH2 tests show no change in recorded RAW ADU levels when either color-space is selected.

did you see the graph with all ISO tested for PDR in http://forums.dpreview.com/forums/thread/3350675

No, I didn't see that yet. Will have a look.

Thanks for verifying/confirming how these things work on the GH2 DM.

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