Sony A7R V ETTR with Zebras.

[Richard A]

I was browsing on YouTube the other night and came across this video. Just wondering if anyone has seen this before. Be sure to watch the whole video. I respect this guy's opinions. I have known of him for years but more his Apple Mac stuff and his cycling rather than photography. I was unaware until now that he had an A7R V. Anyway, something to think about and maybe do your own testing if you want the maximum image quality. Just one thing - the sound quality of the video is very poor. Would like to hear your comments.

https://youtu.be/9F-YUAqZAGo?si=9ckvYewphjacxThc

I should also have linked this video. Although there doesn't seem to be much interest in this...

https://youtu.be/9VoKcZfMLJ0?si=163RNUPOeogXIp8D

 

[jssadowsky]

I was browsing on YouTube the other night and came across this video. Just wondering if anyone has seen this before. Be sure to watch the whole video. I respect this guy's opinions. I have known of him for years but more his Apple Mac stuff and his cycling rather than photography. I was unaware until now that he had an A7R V. Anyway, something to think about and maybe do your own testing if you want the maximum image quality. Just one thing - the sound quality of the video is very poor. Would like to hear your comments.

https://youtu.be/9F-YUAqZAGo?si=9ckvYewphjacxThc

I should also have linked this video. Although there doesn't seem to be much interest in this...

https://youtu.be/9VoKcZfMLJ0?si=163RNUPOeogXIp8D

Richard - thanks for this. I am a retired signal processing engineer, so I'm one of those guys who likes to get geeky about this technology. I watched the first video and some of the second.

First, I learned some things here. I never used the below-base ISO settings because I didn't understand what they do, and I don't use what I don't understand. Now I know it only affects JPEG and histograms. I shoot mainly landscapes and never use in-camera JPEG production. I understand this is important for some photographers (like event photographers) - so weight my comments accordingly. That said, I do not believe there is such a thing as an "optimal exposure."

I also learned about the RawDigger app, which I will promptly buy.

I have an A7R5 and have been using zebras for exposure for several years - my setting is +105. (I learned about zebras for exposure from Mark Gahler.) I am not a fan of ETTR. I want to capture all the details in the cloud highlights and the sky blues. Once you blow out the highlights (usually unintentionally), post-processing is very limited in what it can do to salvage the shot. Modern cameras have a huge dynamic range that (I believe) many photographers don't know how to use. Camera and post-processing histograms only show the top ~6 stops (which is fine because our eyes only have ~6 stop dynamic range). RawDigger did a wonderful thing by displaying the histogram vs. EV (old-school, I prefer "stops") to see the full dynamic range of the 14-bit raw data. The original argument for ETTR (from the old Luminous Landscape website) was that since the sensor's A/D conversion is linear quantization of the (amplified for ISO) photodiode voltage, each successive stop down from full scale has half as many quantization levels. But do the math! For 14-bit data, -10 stops below full scale is a quantization level 2^(14-10) =16, so the step size = log2(16/15) = 0.093 stops. You won't see that (as banding) even if you boost it 4 or 5 stops in post.

I routinely take images that most photographers would say are underexposed, sometimes by 1-3 stops. Coming from an A7R3, one of the coolest features of the R5 is the EV dial that can be unlocked and easily adjusted by thumb. I use the camera's metering mode as a starting point and adjust the EV dial using the zebras to set the exposure. Technically, that is ETTR, but by exposing for the brightest highlights, my shots are generally dark.

In conclusion, IMHO, fine-tuning ETTR is generally not worth the trouble. I prefer having a half-stop headroom at the top to ensure I get all the details in the highlights. The noise penalty of this headroom is negligible.

I wrote an article about noise and dynamic range 5 years ago: https://photopxl.com/noise-iso-and-dynamic-range-explained/ That article has simulations of quantization banding, as well as sensor and photon noise.