21 hours ago
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Re: GH1-GH3 compared at ISO 200
In reply to Anders W,
5 months ago
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Anders W wrote:
Detail Man wrote:
Anders W wrote:
Detail Man wrote:
Anders W wrote:
Fredrik Glckner wrote:
No, I did not use any shadow compensation. I prefer to have as clean as possible in camera processing, and rather do changes to the images later if needed
Figured so. But that means the discrepancy between our results remains a bit mysterious. One additional (although perhaps far-fetched) possibility is that the GH3 plays around with RAW level amplification based on camera settings other than ISO alone. Using ExifTools to inspect the complete EXIF information in the GH3 and E-M5 RAWs I am comparing, I found a setting named GainControl, appearing just before Contrast, Saturation, and Sharpness, which in the GH3 files has the value "Low gain up" but in the E-M5 files has the value "None".
Is this set similarly in your case and do you or anyone else know what this setting is about? Apparently, it is not what Panasonic refers to as "Intelligent dynamic range control". I can see in the EXIF data that the parameter IntelligentD-range is set to off.
From some various GH2 images inspected, and from a set of dark-shots at all ISO settings between ISO=160 and ISO=1600: ISO=160 and ISO=200 show "Low Gain Up" in that Exif tag; and ISO=250 (and all settings above up to ISO=1600) show "High Gain Up".
Nothing special or exotic in any of my GH2 on-camera control-settings in any of the above cases.
Looking through a bunch of GH3 images downloaded from the French site "Hybridcams", ISO=125 and ISO=200 show "Low Gain Up", and the higher valued ISO settings (including 400,800,1600,3200,6400,12800, and 25600) all show "High Gain Up".
"None" is indicated in the field of the same Exif tag labelled "Gain Control" (EM5 @ ISO=200).
Thanks DM. That helps at least a little bit. But do you have any idea of whether this parameter is of any importance when it comes to solving the mysterious discrepancy between my comparisons and those of Fredrik? All the E-M5 and GH3 image pairs that I have at my disposal tell the same story. The "measured ISO" of these two cameras is about the same for the same camera ISO (200), if anything a tad lower for the GH3. This in turn should imply a difference of about one EV between the saturation level of the GH2 and the GH3 when these two are given the same exposure at the same ISO. Yet, Fredrik's RawDigger results seem to indicate a difference of no more than about 1/3 EV.
Two things occur to me.
(1) We know that LR 4.3 is attenuating the GH2 RAW image-data by 0.5 EV (which we know is not the case where it comes to the GH3 RAW image-data).
Yes, and these values indicates that the truth would be somewhere between Fredrik's and my results.
I thought that your information was derived from RawDigger analysis only, right ?
On the other hand, as I told you in the other thread, the baseline value of 0 for the GH3 may be too low relative to the +0.5 of the E-M5. When looking at the files in LR, I have to reduce exposure on the E-M5 by half a stop (or increase it on the GH3 by the same amount) to reach roughly the same brightness.
Using Lightroom 4.x, right ? (If somehow referenced from sensor saturation levels, and not from equal exposure), that observation would seem to indicate that the GH3 and EM5 have similar "Saturation ISOs", as you have suggested ?
(2) The table that remains presently posted on the web-page:
http://m43photo.blogspot.com/2012/12/gh1-gh2-and-gh3-iso-200.html
... is stated to not reflect a black-level offset of 144 being applied to the GH3 RAW image-data in RawDigger - which will cause the Average statistics for the image-data to decrease significantly.
Yes. But even with the correct black-level value subtracted, the GH2 saturation is only about 1/3 EV higher than that of the GH3 based on those figures. That's what puzzles me. The difference expected from my vantage point is about one EV.
While the OP has talked (in generalaties) on this thread about the resulting RawDigger "Average" vales after applying balck-level subtraction (of 144) to the GH2 RW2 image-data, the table presently published on the OP's blog (and the only numbers that we have to calculate with) are cleary stated in that blog-post to be the results found without any black-level subtraction ...
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