UniWB and ETTR with (Pentax K-30)

Foreword

• using ETTR (and my configuration) will most likely result in overexposed highlights, unless extreme care is taken;
• (for me) it is impossible to get UniWB configured on Pentax K-30;
• if you do get close to having a "truthful" RGB histogram (at least with my configuration) then the live-view feature is almost useless (especially for composition and in high contrast scenes), as it will show only shades and contours; (however it is quite useful for assessing focus while using the focus peaking feature;)

About UniWB and ETTR

Although UniWB (Unit White Balance) and ETTR (Expose to the Right) are technically two different subject matters they are tightly related, therefore I have lumped them together. UniWB deals with "forcing" the camera to present a "truthful" histogram for the individual RGB channels, not skewed by the white balance channel multipliers (which most often than not give the impression that the red and blue channels are overexposed, meanwhile they are in fact underexposed by half up-to a full stop). ETTR is a technique, usable only when the scene's contrast is lower than the camera's exposure range (colloquially called "dynamic range"), that allows the photographer to take advantage of the camera's full exposure range (or exposure latitude), by overexposing the scene just before the highlights are not overexposed (i.e. blown-out to complete white). Therefore a "truthful" histogram for the individual RGB channels is essential for ETTR, which in turn implies having both UniWB and linear contrast curves.

Configurations

Version 1.1

• white balance:

  • White balance	K
    Color Temperature	3700K
    Adjustment	G7 and B1

• custom image:

  • Custom image	Natural
    Saturation	-2
    Hue	0
    High/Low Key Adj	-2
    Contrast	-2
    Sharpness	0

• miscellaneous:

  • Color Space	AdobeRGB
    Highlight Correction	Off
    Shadow Correction	Off
    LCD Display Settings / Blue-Amber	7 (maximum towards amber)
    LCD Display Settings / Green-Magenta	7 (maximum towards magenta)
    WB When Using Flash	2 (unchanged)

Version 1.0

• all of the above for version 1.1, except the following;
• custom image:

  • Saturation	-4
    High/Low Key Adj	-4
    Contrast	-4

Observations

• the closest I got to UniWB are the following RGB multipliers: (R) 1.519531, (G) 1.000000, (B) 1.515625;

• the white balance configuration is essential into tricking the camera to use the RGB multipliers as close as possible to the unity (i.e. 1.0); (thus essential for UniWB;)

• the custom image configuration is essential into tricking the camera to use a contrast curve as close as possible to a linear one; (I have the feeling the camera is "umping" the knobs to make the image "pop";) (thus helpful for ETTR) (although I'm not that certain about this...)
• one can easily confine this configuration to one of the custom modes, enabling the M and other automatic modes to have "normal" configurations;
• the LCD configuration is skewed towards amber and magenta to counteract the skewed white balance, else the displayed images will look too greenish; (note that this configuration doesn't affect the embedded JPEG, and thus neither the RGB histogram;) unfortunately the LCD configuration is global, thus applying also for the M and other automatic modes regardless of your choices for a particular custom mode, therefore one should decide (depending on how often UniWB is used) if the LCD configuration is to be applied or not;
• highlight and shadow corrections should be off, especially for ETTR, because the camera will try to "fix" over- / underexposed images, thus yielding a "lying" histogram;

Links

Links related to ETTR

• Expose (to the) Right -- Maximizing S/N Ratio in Digital Photography;

• A Possible Problem with Expose to the Right! -- Settings for an Accurate Histogram;

• ETTR: ISO vs shutter speed;

• 'Expose to the Right' is a Bunch of Bull;

• Dynamic Range Is Not Exposure Range! Part I;

• Dynamic Range Is Not Exposure Range! Part II;

• ETTR Is Critical For High ISO Photography;

• The ETTR Myth;

• ETTR -- Expose to the Right;

• Gamma Demystified;

• Un-debunking ETTR;

• Why "Expose to the Right" is just plain wrong;

• ETTR for the fourth time........;

• Debunking ETTR;

• Using in-camera histograms for ETTR;

• Bit Depth and Dynamic Range;

• Get wide right! (shooting with the Fujinon XF 14mm F2.8)

• While writing with light you sometimes need the right 'pigment';

Links related to UniWB

• What is UniWB? (quick introduction to the subject);

• Introduction to UniWB (another introduction to the subject);

• UniWB -- Make camera display reliable (lengthy description on how to achieve it);

• UniWB -- settings and results (original in Russian) (translation to English);