selmslie Loc: Fernandina Beach, FL, USA

Sony's Zebras are probably the most useful tool since they give us a heads up on the chance of blowing the highlights. But then I have only one camera that provides that, my A7 II.

For all other cameras the blinkies give me instant feedback if I have exposed too much. They also tell me where the highlights are threatened and I can take immediate steps to counteract that if I want to.

But ultimately it boils down to a familiarity with the interplay between incident light and reflective nature of common surfaces. These properties are relatively constant and an incident light meter will cover any uncertainty about unfamiliar lighting conditions.

But broad daylight through heavy overcast all the way to dusk are lighting conditions that you can commit to memory. Once you are comfortable with these situations you should be able to figure out exposure without resorting to any additional tools.

It also helps to be able to recognize whether a scene has a wide or narrow dynamic range. For the former, even ETTR might not suffice. For the latter ETTR is usually unnecessary.

Where things get tricky is with artificial light of any sort. But here too, the blinkies are a better way to deal with exposure than histograms or other means.

And remember that it's perfectly OK to let some of the scene fall into Zone 0 - pure black. That's what I like about the photography of Ralph Gibson.

Budgiehawk

I understand how to use the histogram for luminosity but not what to to with the histograms for colors. Can anybody give me a clue?

Jsykes

Re the comment on Blinkies and ETTR. I'll probably struggle to articulate this correctly.... but is the theory with ETTR that you focus on creating an exposure where the histogram is as far right as possible without the image demonstrating blinkies; because of the ability to address over exposure in post processing? The

rmalarz Loc: Tempe, Arizona

You're on the right track. ETTR/EBTR is pushing the exposure such that the highlights never exceed the camera's capability to capture detail in those highlights. This excludes specular highlights. The issue resides in the fact that cameras produce the histogram from the camera-generated jpg. Thus, the RAW file can contain additional information that the in-camera jpg would be hard-pressed to produce.

Additionally, overexposure is just that, way too much. What ETTR/EBTR does is push the exposure up to, but not exceed the camera's RAW capabilities to capture the highlight data. Thus, it's additional exposure, not overexposure.
--Bob

Jsykes

Bob

Many thanks for the clarification.

Obviously not scientific but is a small degree of blinkies still OK as well as a snall part of the histogram displayed touching the right edge?

John

selmslie Loc: Fernandina Beach, FL, USA

It depends on your camera. Based on tests I have done with Nikon, Sony and Fuji sensors (and others have confirmed this with Canon sensors) the blinkies begin about one stop (+/- about a third of a stop) before the raw file blows out. For a 14-bit raw file this is close to the 8191 level where 16383 is the highest value the raw file can record.

In all of the cameras I have tested, the red and blue channels might reach 16383 but the green channel usually maxes out about 1/4 stop lower. It's the green channel you need to worry about because in a white cloud the green raw channel ends up further to the right than blue or red.

The bottom line is that, if you see any blinkies at all, you will probably need to develop the image from the raw file and recover some highlights. But if you cut back the exposure until you see no blinkies then the JPEG should not appear to be blown out. The difference may be no more than 1/3 stop and that's not enough to make any difference in the shadows.

You will need to download this screen shot and look closely at the right end of the histograms.

This image was exposed about 1.7 stops brighter than Sunny 16.

RawDigger plot of the raw file histograms where the whitest clouds were showing blinkies

(Download)

selmslie Loc: Fernandina Beach, FL, USA

They tell you that the red, green and blue channels are slightly different in content but you can already see that just by looking at the image.

The luminosity channel closely tracks the green channel and that's where the image blows out first when you highlights are close to white.

There is little you can do with the RGB histogram information for a normal scene that you could not already do with the luminosity histogram.

Jsykes

Bob

Awesome answer

Doc Barry Loc: Huntsville, Alabama USA

Simple answer is to read about histograms. An excellent ebook on this subject is "Mastering Histograms" by Al Judge. Kindle version is just $5. https://www.amazon.com/Mastering-Photographic-Histograms-fine-tuning-exposure/dp/1539538222

Enjoy!