Some input on "recovering skies"

From RawTherapee camconst.json:

    { // Quality A, ISO and aperture WL data by CharlyW at RawTherapee forums, missing samples safely guessed
        "make_model": "Canon EOS 7D",
        "dcraw_matrix": [ 5962,-171,-732,-4189,12307,2099,-911,1981,6304 ], // Colin Walker
        //"dcraw_matrix": [ 6844,-996,-856,-3876,11761,2396,-593,1772,6198 ], // dcraw
        "ranges": {
            "white": [
                { "iso": [ 100, 125 ], "levels": 13480 }, // typical 13584
                { "iso": [ 160, 320, 640, 1250, 2500 ], "levels": 12550 }, // typical 12650
                { "iso": [ 200, 250, 400, 500, 800, 1000, 1600, 2000, 3200, 4000, 5000, 6400, 12800 ], "levels": 15200 } // typical 15304
            ],
            "white_max": 16383,
            "aperture_scaling": [
                // no scale factors known for f/1.2 and f/1.0 (no lenses to test with), but the
                // typical 12650 white levels maxes out at "white_max" for f/1.4 and below anyway.
                { "aperture": 1.4, "scale_factor": 1.250 }, // guessed
                { "aperture": 1.6, "scale_factor": 1.150 }, // guessed
                { "aperture": 1.8, "scale_factor": 1.110 }, // 15196/13584
                { "aperture": 2.0, "scale_factor": 1.080 }, // 14734/13584
                { "aperture": 2.2, "scale_factor": 1.050 }, // 14386/13584
                { "aperture": 2.5, "scale_factor": 1.040 }, // 14272/13584
                { "aperture": 2.8, "scale_factor": 1.030 }, // 14042/13584
                { "aperture": 3.2, "scale_factor": 1.015 }, // guessed
                { "aperture": 3.5, "scale_factor": 1.000 } // guessed negligible
            ]
        }
    },