Been thinking about this lately. Years ago it was a given that you needed to expose to the right to get the max out of your camera. At least it seemed that it was the prevailing wisdom. I followed it because, again, it seemed like it was the prevailing wisdom. But now I'm starting to wonder if it was ever a really good idea.

I will probably not articulate this as well as I hope but here goes. It seems to me that when you do ETTR that you are making a conscious exposure choice. And that choice is that you are taking the exposure out of your hands. That is, once you've done ETTR you lock yourself into a particular exposure type. It always seemed to me that it was much harder to do certain types of looks in post when you start with ETTR. Something that would have been resolved if I had decided upon what exposure I wanted (where I want the histogram) at the capture time.

Now for the controversial part... I wonder if ETTR is just a crutch to avoid having to determine your exposure properly. Like using Automatic instead of Manual. I just keep seeing that as I take more control over exposure at the time of capture I get results I like far better than I ever got with ETTR and I wonder if it is because ETTR a shotgun when we usually only need a sniper rifle.

Just a thought. Curious if anyone else has insight or has thought about this kind of thing. And if you want to tell me I'm an idiot that is fine, too.

I have read (but can't find right now) a couple of pre-release suggestions that the D800 is better at (or maybe has more emphasis on) shadow detail, and that with the D800 you may be better exposing to the center or left rather than right

But again, I can't find that reference now, but am curious as well. To date I have not had access to PS or Lightoom with mine to experiment on which is the easier direction to correct, toward the right or left?

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I don't get how ETTR takes exposure out of the hands of the photographer. It's not auto, it's a specific exposure choice that has to be tightly controlled in order to prevent blown highlights. It IS a choice to see the camera as a data collector, not something that makes pictures. With ETTR you are making the conscious choice to collect data at capture, and make the picture in post.

ETTR is a method that uses your camera to optimize data capture. With optimum data, your pictures don't necessarily look as intended out of camera, but you have the most data which gives you the most flexibility in post processing. Whether you shoot this way, or shoot for results out of camera, both are conscious choices and neither is auto. I'm not sure what look you'd be going for in post that you couldn't achieve with ETTR, unless you blew the exposure and lost highlights.

As to why, there's a reason behind the prevailing wisdom. There are in fact a couple reasons.

Light is a geometric scale, mapped by our cameras into a linear scale. 1 stop of light is a doubling of the amount of light. Converted to a numeric value by analog to digital conversion, that means the difference between 16 and 32 is one stop, 32 to 64 is one more stop, and 64 to 128 is one more stop, etc. In a 12-bit conversion, the numeric value can range from 0-(2^12-1) or 0-4095. The brightest stop of light that can be recorded therefore contains a numeric range of 2048-4095. That's a full half of the numeric scale! The next stop has a range of 1024-2047. Your brightest 2 stops contain 3/4 of your numeric range! Now consider the numeric range of all 12 stops:

2048-4095 or 2048 counts
1024-2047 or 1024 counts
512-1023 or 512 counts
256-511 or 256 counts
128-255 or 128 counts
64-127 or 64 counts
32-63 or 32 counts
16-31 or 16 counts
8-15 or 8 counts
4-7 or 4 counts
2-3 or 2 counts
0-1 or 1 count

So, on a 12-bit capture, your brightest stop has the ability to contain 2048 gradations, and your darkest stop only 1. This is why you expose to the right, because let's say your data spans 8 stops. You really want it to occupy the top 2/3 of that table, not the middle, and certainly not the bottom! 8 stops of data in your file could contain a numeric range of 16-4095 (ETTR, 4079 potential gradations), or 4-1023 (centered histogram, 1019 potential gradations) or 0-255 (exposed to the left, 255 potential gradations, and equivalent to jpeg bit depth).

At the top you have captured the most data, numerically the most detail, and you have the most flexibility in post processing. This is one reason why, when you try to brighten shadows, they have a tendency to be noisy and lack detail, because you're re-mapping an area on the scale where there is little potential for detail.

Another aspect to ETTR is signal-to-noise ratio. If your sensor produces a fixed amount of noise, you get improved SNR by giving the sensor more data (light) to the fixed noise, although with today's cameras I'm not sure this is as much a concern.

Larry - a Bay Area Nikonian
My Nikonians gallery

www.tempered-light.com

I don't have a lot of time for a reply but I do understand the steps and math very well. But I think that other people may not so having that in your post will help a lot of people.

The core of my post is that I never seem to get the results in post thst i like when I use ETTR than when I set the exposure to exactly what I want at capture time. It always feels like something that should be helping me but rarely does.

Neil, I'd always recommend you do what best gets you the results you are looking for. In theory more data should allow more flexibility, but if you're not able to convert that data into results then theory does you no good!

Larry - a Bay Area Nikonian
My Nikonians gallery

www.tempered-light.com

>As to why, there's a reason behind the prevailing wisdom.
>There are in fact a couple reasons.
>
>Light is a geometric scale, mapped by our cameras into a
>linear scale. 1 stop of light is a doubling of the amount of
>light. Converted to a numeric value by analog to digital
>conversion, that means the difference between 16 and 32 is one
>stop, 32 to 64 is one more stop, and 64 to 128 is one more
>stop, etc. In a 12-bit conversion, the numeric value can range
>from 0-(2^12-1) or 0-4095. The brightest stop of light that
>can be recorded therefore contains a numeric range of
>2048-4095. That's a full half of the numeric scale! The next
>stop has a range of 1024-2047. Your brightest 2 stops contain
>3/4 of your numeric range! Now consider the numeric range of
>all 12 stops:
>......
>
>So, on a 12-bit capture, your brightest stop has the ability
>to contain 2048 gradations, and your darkest stop only 1. This
>is why you expose to the right, because let's say your data
>spans 8 stops.

nice explanation but it has been demonstrated that the real reason to ETTR is what you said below

>Another aspect to ETTR is signal-to-noise ratio. If your
>sensor produces a fixed amount of noise, you get improved SNR
>by giving the sensor more data (light) to the fixed noise,

here is the reason that noise eliminates our perception of banding and quantization in the darker tones

http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html#bitdepth

so ettr is still valid to avoid noise-even though sensors are better they are not noise free-especially with long exposures or high iso.

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Am I right that the histogram is influenced by the in camera
picture control settings? If so, when shooting raw, how do you
get the histogram to accurately relate to the raw file? Is it
sufficient to simply zeroise all the picture control settings?

I don't think your camera lets you display a true Raw histogram. To come at least close I set the picture control on "neutral", "sharpening" and the other four sliders to zero. ADL and noise reduction are set to off.

This way the changes in the Raw histogram should be minimized.

Tristan

Visit my Nikonians gallery.

Visit my Nikonians gallery.

Good point, Albrecht. The histogram display is based on the JPG rendered from the RAW file. Setting camera adjustments as you stated will minimize changes to the histogram that might change the right end point.

Jon Kandel
A New York City Nikonian and Team Member
Please visit my website and critique the images!

>I don't get how ETTR takes exposure out of the hands of the
>photographer. It's not auto, it's a specific exposure choice
>that has to be tightly controlled in order to prevent blown
>highlights. It IS a choice to see the camera as a data
>collector, not something that makes pictures. With ETTR you
>are making the conscious choice to collect data at capture,
>and make the picture in post.
>
>ETTR is a method that uses your camera to optimize data
>capture. With optimum data, your pictures don't necessarily
>look as intended out of camera, but you have the most data
>which gives you the most flexibility in post processing.
>Whether you shoot this way, or shoot for results out of
>camera, both are conscious choices and neither is auto. I'm
>not sure what look you'd be going for in post that you
>couldn't achieve with ETTR, unless you blew the exposure and
>lost highlights.
>
>As to why, there's a reason behind the prevailing wisdom.
>There are in fact a couple reasons.
>
>Light is a geometric scale, mapped by our cameras into a
>linear scale. 1 stop of light is a doubling of the amount of
>light. Converted to a numeric value by analog to digital
>conversion, that means the difference between 16 and 32 is one
>stop, 32 to 64 is one more stop, and 64 to 128 is one more
>stop, etc. In a 12-bit conversion, the numeric value can range
>from 0-(2^12-1) or 0-4095. The brightest stop of light that
>can be recorded therefore contains a numeric range of
>2048-4095. That's a full half of the numeric scale! The next
>stop has a range of 1024-2047. Your brightest 2 stops contain
>3/4 of your numeric range! Now consider the numeric range of
>all 12 stops:
>
>2048-4095 or 2048 counts
>1024-2047 or 1024 counts
>512-1023 or 512 counts
>256-511 or 256 counts
>128-255 or 128 counts
>64-127 or 64 counts
>32-63 or 32 counts
>16-31 or 16 counts
>8-15 or 8 counts
>4-7 or 4 counts
>2-3 or 2 counts
>0-1 or 1 count
>
>So, on a 12-bit capture, your brightest stop has the ability
>to contain 2048 gradations, and your darkest stop only 1. This
>is why you expose to the right, because let's say your data
>spans 8 stops. You really want it to occupy the top 2/3 of
>that table, not the middle, and certainly not the bottom! 8
>stops of data in your file could contain a numeric range of
>16-4095 (ETTR, 4079 potential gradations), or 4-1023 (centered
>histogram, 1019 potential gradations) or 0-255 (exposed to the
>left, 255 potential gradations, and equivalent to jpeg bit
>depth).
>




Michael Reichman doesn't know his math, and a whole bad set of wrong ideas developed.

1. Mathematically a "doubling" of something (in this case LIGHT INTENSITY, and not tonal values as Michael thinks)is shown as 2,4,8,16,32, 64....2048,etc. Each interval is the SAME (a doubling effect). There is NO increase in qty of light between interals, and it DOES NOT refer to tonal values. It only says that it is twice as bright at 2048 compared to 1024 (1 stop diff). The same holds true that it is twice as bright at 1024 compared to 512 (1 stop diff). It does not mean 512 tones or 1024 tones....that scale has nothing to do with qty.

2. Expose a black card next to a white card, each if IDENTICAL size. Now look at it on the histogram. You will see that the peaks are just as high for both the white and black patc. The peaks on a histogram represent number of pixels exposed for a particular tonal value between o-255. You will find that the QTY of pixels exposed for the black patchy is the same as for the white patch (if they were identical size). The peaks for both are equal.

3. Shadow noise is due to sensor performance, not because less information is recorded in the darkest zones compared to brightest zones.

4. A sensor is like film in recording data. The light falls where it must on the sensor to create the image, and each image will show a different histogram. Try plotting Reichmans scale 1,2,4,8,16...2048 which he considers as a QTY of something on a histogram, and you always get the same result (straight line ascending to the right which is nonsense). Light falls where it wants to on the sensor, not in any order as he suggests.

I recommend people read Ansels books on sensitometry, or pick up some math books. Michael is a photographer, and his buddy Thomas Knoll apparently were on a trip together when they came up with this nonsense. They should have got a piece of paper, and wrote down what the x and y axis mean on a histogram (one is for qty, the other for tonal value). Two cards photographed at zone 3 and 7 will have identical peaks (same quantities of pixels exposed for that tonal value). There isno descendinig order as the table above shows.

The histogram shows it all....read what is there.... Qty vs tone value (0-255). Do you see on the histogram anywhere the scale 1,2,4,,8,16,32....2048? For further reading check out math books on statistics "interval data".

I rushed through this, and hope it makes sense.I would stick to the cameras exposure (Nikon knows a few things), but i agree if you got time it won't hurt to use ETTR, but I prefer to see the mood or affects as is on the cameras lcd and worry less about blocking highlights when rushing.

My opinion is that you both need to reread a text on how light is measured and stored by a sensor. Since the sensor (measurement) is linear and the light scale is logarithmic, there is far more data (discernible gradations) in the shadow end of the spectrum than in the highlight end. This is precisely why Dlighting works better pulling detail out of the shadows than the highlights.

I have always shot digital in the same way I learned to shoot transparency film: expose to protect the highlights. If you blow the highlights they are gone. If you loose some shadow detail, some can be retrieved in post.

Noise is more obvious when pulling data from the shadows but this is due to the signal to noise ratio (charge from photons hitting the sensor vs. electrical noise) when the data is collected. The more photons, the higher the signal and the better the signal (photon charge) to (electrical) noise ratio and therefore less visual noise in the images.

The moral of the story is to make your exposure such that the histogram is used edge to edge without saturating at the far right and you'll have the maximum amount of data the raw file can hold.

Matt Hutchinson
D700, D300, 18-35, 28-70, 80-200, 24, 50, 85, TC-14eII, SB-800's, SB-600's

'My opinion is that you both need to reread a text on how light is measured and stored by a sensor. Since the sensor (measurement) is linear and the light scale is logarithmic, there is far more data (discernible gradations) in the shadow end of the spectrum than in the highlight end. This is precisely why Dlighting works better pulling detail out of the shadows than the highlights.'
--------------------------

The sensor is linear, but so is light, only we chose a log scale for convenience in graphing it. You could have chosen any other base. Dlighting does not work for the reasons you describe.I could open up shadows in an analog image with dodging and also see more resolution in shadows. Our eyes simply prefer lighter then darker blocked up areas that can be unblocked by dodging. Noise is seperate issue from resolution (36mp is the resolution of the camera, how it is affected down the pipeline is a seperate issue, as is magnification). The resolution is the same in the shadows and highlights, and nothing to do with the crazy idea of ETTR. Now your telling me the exact opposite. Try the test.,...shoot a white and dark patch (equal size), and you will see identical amount of pixels used for the dark and light patch...observe the peaks which refers to qty of pixels. Same amount of pixels for both patches means same resolution, although noise dummies down resolution at lower tones.

I don't believe inn ettr, but it won't hurt either if you watch your highlights and don't mind viewing overexposed images on your cameras lcd, rather then see the mood (to me more important). It won't help improve your artistic vision, and more likely mean you miss the shot chimping too much. This is a subject suitable for those qualified, so we get the right answers, and for many of us we wouldn't understand the theory anyways. I'm not a sensor or camera engineer, and I think that holds for the rest of us....so opinions are only that.It would actually be better to say nothing, then something wrong. But we all love making an opinion, as i do. However, a histogram is easy to read, there is not much too it (qty vs tonal values at bottom), and if your viewfindeer is filled evenly with the left side at zone 3 and the right side at zone 7, the histogram will show 18million pixels for the left and 18 million for the right (the peaks in the histogram are identical). That is all we need to know.

I have found Micheal Reichman never accurate in his articles. His Ettr concept is wrong. He has stated 10mp matches medium format,then later said a p45 digital back (39mp) equaled 4x5. All proven wrong in time. He has never been right, but likes the attention his website gets....because he is not a scientist, engineer on cameras or sensors. Would you listen to him for medical advice (remembering he is just a photographer). His comment was made years ago, and still his errors are talked about, benefitting his site. I'm outta here...this issue will never be resolved...too many things to discuss and comes into play.

The philosophy of exposing to the right (ETTR) grew mainly out of the early days of digital photography, and was recommended for one key reason: The digital cameras of those early days were not able to capture the full dynamic range of most scenes. Exposing to the right would often give you a pleasing if not, technically correct, result.

In fact, the ETTR philosophy will only work 'right' if there are pure white tones somewhere in the image. An image filled with grays and dark tones will not be rendered correctly if you ETTR.

However, if you ETTR and adjust the images in post processing, you can achieve the maximum dynamic range capabilities of the camera.

Russ
Nikonian Team Member
Russell MacDonald Photography
Nikon CLS Practical Guide

I agree with Russ that modern sensors with their greater dynamic range have rendered the use of ETTR moot. That said, I can envision a shot — street scene at night, no highlights, just blacks and grays — where overexposing the capture and reducing the exposure in post processing gives a greater latitude to make adjustments. It gives a cushion, more data to be manipulated.

But truth be told, with my D3s I rarely do this anymore.

Jon Kandel
A New York City Nikonian and Team Member
Please visit my website and critique the images!