Digital Sensitometry for Black and White ~ Automation ~ RAW and In-Camera jpg image processing

[Updated 7 October, 2024 ~ Important correction: Zone 5 at 0EV is 76hex/118decimal, not 7F/127 as I previously wrote.]

It's taken more than a few blog posts to get here.  At long last I come to the  question I had that launched this little digital sensitométrie adventure.

Original question: Is it possible to generate a decent black and white image in-camera?

Using the Zone System as a framework of understanding, from here on out the answer to this question should be quick and relatively easy.   So I'll dispense with my usual background/setup hoo-haa and get down to it.

RAW automation ~ 

Adobe Standard camera profile

I have to admit that manually controlling RawTherapee can be a bit scary.  There are so many options, so many tools, and so many operations to choose from.  Which is why it might be useful to look at an automation in the form of a camera profile to see how far down the Zone System road I can get on RAW file import.

Using the baseline Zone 5 as 0EV luminance reference, I took a look at Adobe Camera Standard .dcp. In RawTherapee I enabled Tone Curve, Base Table, and Look and looked at just the luminance channel.

Advantages -

• Easy to load a .dcp file into RawTherapee or Photoshop (where I'm sure it comes with the system as well as in Adobe's ACR tool)
• Pre-defines a usable tone curve
• Uses 0EV as Zone 5 so no "unusual" exposure compensation normally required
• Tames +1EV to +4EV light area transitions 
• Expresses more than 11EV dynamic range
  
• Input correction curves easily constructed to Zone System references
• Working from RAW allows greater flexibility in extreme image processing
  

Disadvantages -

• Black and white conversion required
• -0.3EV underexposure might help meet the idealized step wedge reference (see how the Adobe Standard curve is to the left of the reference)
  
• Zone 9 at +4EV remains the pure white saturation point (not Zone 10, +5EV as described by the original Zone System)
  

In-camera automation ~ using the jpg engine ~ 

Sony Creative Style Light

Flying by the seat of my pants and using years of experience printing black and white images I found that Sony's in-camera jpgs generated using Creative Style Light looked pretty good when I downloaded images and simply desaturated them off-camera.  

So it didn't surprise me when I measured the luminance curves using settings of Contrast -2, and Saturation -1 that the idealized Zone System step wedge is matched by desaturated Creative Style Light.

Advantages -

• Exactly matches idealized Zone System step wedge
  
• Expresses 11EV dynamic range
• Uses 0EV as Zone 5 so no "unusual" exposure compensation normally required
• RAW+jpg function available 
• Could be a good solution for posting converted black and white images when outside of Big Computer range (ie: while on the road) where I could have color (if I like Light colors) and monochrome jpgs
  

Disadvantages -

• Black and white conversion required
• Zone 9 at +4EV remains the pure white saturation point (not Zone 10, +5EV as described by the original Zone System)

Sony Picture Profile ~ Cine 4, Black and White

Sony camera features have evolved to include configurable video tone and color controls. The tool can be used for stills photography as well.

I found that Gamma Cine 4 raises the midtones. Setting Color Mode to Black and White performs a full black and white conversion in-camera.

Advantages -

• Delivers in-camera generated jpg that addresses the original question
• Configurable for a variety of parameters that can match idealized Zone System step wedge where users can configure ->
  
• Knee to define highlight roll-off characteristics
• Black Gamma to define the point of pure black
• Color Depth to build in-camera B&W filters thru RGBCMY channel controls - which I find to be an excellent feature
  
• Detail to control image sharpness
  
• Expresses 11EV dynamic range
• Uses 0EV as Zone 5 so no "unusual" exposure compensation normally required, though...
  
• RAW+jpg function available  
• Could be a good solution for posting black and white images when outside of Big Computer range (ie: while on the road) 

Disadvantages -

• Limited legacy camera support ~ Picture Profiles are available on certain Sony cameras beginning with A6300, A7S, A7II, and A7RII
• In practice, underexposure of -0.5EV or -0.3EV might be useful (see how the curve is to the left of the idealized step wedge)
  
• Camera exposure bracketing functions are not available
• Shooting while camera in Silent Mode not available
  
• Best used configured before a shoot - menu diving to change settings might be annoying during actual photography
  
• Tones in Pure White (which might relate to a video standard)
• Zone 9 at +4EV remains the pure white saturation point (not Zone 10, +5EV as described by the original Zone System)

Creative Style Black and White, contrast = 0

Turning to Sony's Creative Style Black and White, I first looked at how this style behaves at its default settings.

Advantages -

• Delivers in-camera generated jpg that addresses the original question
• Uses 0EV as Zone 5 so no "unusual" exposure compensation normally required
• Exposure bracketing functions available 
• RAW+jpg function available 
  

Disadvantages -

• Zone 5 to Zone 0 are darker than the idealized step wedge standard (which is here I saw problems in my own work)
  
• Expresses 10EV dynamic range
• Zone 9 at +4EV remains the pure white saturation point (not Zone 10, +5EV as described by the original Zone System)

Creative Style Black and White, contrast =-3

On a lark I thought I'd try Sony's Creative Style Black and White with the contrast turned down to the minimum -3.  Surprise! This simple setting seems to do the trick.  The dark regions under Zone 5 shift to the left to move up the exposure scale which correctly "opens up" the shadows.

Advantages -

• Delivers in-camera generated jpg that addresses the original question
• Expresses 11EV dynamic range 
• Uses 0EV as Zone 5 so no "unusual" exposure compensation normally required
• Exposure bracketing functions available 
• RAW+jpg function available
• Could be a good solution for posting black and white images when outside of Big Computer range (ie: while on the road) 
  

Disadvantages -

• Zone 9 at +4EV remains the pure white saturation point (not Zone 10, +5EV as described by the original Zone System)

I'm no longer flying by the seat of my pants when it comes to black and white photography and I believe I've adequately answered the original question.

--------- Where am I on my checklist of perceived "needs"? ---------------

Is what I'm doing here in trying to transfer old film-based Zone System knowledge into something practicable for digital...

• Measurable - Yes
• Accurate - Yes
  
• Repeatable - Yes
• Controllable - Yes
• Clearly understandable - Yes, but readers can judge otherwise if they like
  
• Reveals what Sony's in-camera jpg processor is doing - Yes
  
• Helps me choose a set of in-camera jpg engine operations and/or settings that match my RAW output - Yes, with certain perhaps narrow/small limitations
  
• Huge Bonus: I now have a linear Zone System digital match to the old idealized film-based Zone System for both RAW and jpg files.
  

Note: What I'm sharing in this series is limited to my experience with Sony full frame and APS-C mirrorless cameras and the sensors they come with.  In truth I have zero idea how other digital systems map tones, though I'm developing my own suspicions.  I hope the descriptions of what I'm doing here helps interested parties sort this out for their situations.  If not, let me know and I might lend a hand.