Why no automatic exposure to the right w/o blown highlights?

<p>Hi everyone,<br>

why can't current Nikon DSLRs (to my knowledge) be set to automatically use the full dynamic range of the sensor (by exposing to the right) while avoiding blown highlights. Many photographers will tell you to always set your camera to do just that in order to achieve the best file quality and then adjust exposure in post processing. If this is true, wouldn't it be a great feature to have the camera do this for you, e.g., automatically chose the correct amount of exposure compensation? What am I missing? Thanks.</p>

<p>Why? I don't know but the D300 does it better than the D70 did.</p>

<p>What you're missing is "Active D-Lighting" - a feature on my D300 that I'm just starting to truly appreciate. Seems to do a remarkable job of keeping those highlights under control. Whether and when to use it (and how aggressively - "normal" vs. "high") is taking some time to build into my mental workflow while out shooting... but so far I've seen some dramatic improvements in how I'm recording scenes in tricky, contrasty light when I don't have time to chip and study the histogram.</p>

<p>.</p>

<p>Jacob, you seem to be saying that the old film capture criteria of zone previsualization is inappropriate for the digital Raw capture world where all of that zone placement stuff can be done after capture, and instead, you want the camera to capture everything possible in an endless dynamic range without regard for photographer's eventual criteria for zone placement on screen or on print output. Have I got it?</p>

<p>I'm not saying that's good or bad, just different than it used to be with film. </p>

<p>Also, you seem to be saying that your camera does not already automatically do that, and you wonder why. Have I got it? </p>

<p>I think they all try, just some capture a wider dynamic range signal over noise than others (you get what you pay for?). What dynamic range and signal to noise ratio do you want that you are not getting?</p>

<p>.</p>

<p>Jacob, my best guess at this would be that shooting conditions vary so widely that it's better for the photographer to decide when to use exposure compensation to push your histogram to the right. The D300 does a superb job of metering but some situations, like a lot of bright snow, still "fool" the camera and are better adjusted individually. Would we all use exposure compensation for all scenes? I don't think we would and I don't think most of us would want the camera to do it for us. Could the camera's electronics be designed to recognize when to adjust it and do it? I don't know. Interesting to think about, though.<br>

Dick</p>

<p>The matrix meter has (was it) 1005 elements; the imaging sensor has 10 to 24 million. Thus a highlight may appear not blown according to the matrix meter while it is blown in the actual data recorded by the sensor. Therefore, to do ETTR, the camera would need to be in live view mode and adjust the exposure so that it satisfies the criteria just at the moment you take the actual picture. I don't see how ETTR could be done without iterating the exposure which is slow, therefore it may not be realistic in a fast-changing situation.</p>

<p>In any case a lot of people would prefer the image to look decent out of the camera with straight raw conversion, so that they don't have to adjust every single image. There may also be situations where a highlight should be blown to improve other parts of the image. I don't do ETTR at all, I aim to produce an exposure which requires minimal post-processing, since life is short.</p>

<p>.</p>

<p>Jacob, more to the point, my Raw "developer" software offers + / - 2 stops exposure compensation <em>after the fact</em> . </p>

<p>If this is what you are after when trying to print the <strong><em>tone/chrome/zone placement</em> </strong> and <strong><em>dynamic range</em> </strong> and <strong><em>signal to noise ratio</em> </strong> that you are after, then maybe your inquiry is not so much "<em>why don't cameras blah-blah-blah</em> " as much as you're really asking, "<em>how do <strong>I</strong> find blah-blah-blah in my Raw developing software?</em> ". </p>

<p>My point is that once we have Raw capture in our years and years of archives, camera exposure controls and smarts no longer matter, and we're gonna revisit our Raw image files themselves over the years and re-"develop" them to our newest criteria and savvy. </p>

<p>My Raw "developer" permits that. What Raw" developer" are you using, and what printer/ink/paper is your target under what lighting? This is your target, yes?</p>

<p>.</p>

<p>Jacob is correct, ideally you would want to expose your picture, so that the histogram is being pushed to the right without clipping the highlights. The resulting RAW file might look pretty bad as captured, but processing that RAW file will yield the highest quality print. It would be nice if a camera could perform that "push to the right" automatically - but only for RAW files!<br>

I practice that type of shooting by checking the histogram after every shot and compensating exposure accordingly.</p>

<p>.</p>

<p>So, Juergen and Jacob, am I correct in assessing your comments that zone placement previsualization a la Ansel Adams is dead, and Raw capture is merely all about grabbing the absolutely most original scene dynamic range over noise as possible, and then we can whimsically place tone/chrome/zones in the output, according to our artistic satisfaction, as a separate step after capture?</p>

<p>And anyone who tweaks exposure during capture is shortcutting the Raw capture accuracy process for their own convenience, but they are compromising "total Raw capture accuracy" of their stored Raw?</p>

<p>Do we have two different processes here to hit the same initial output target, the old <em><strong>film-way</strong> </em> compromises revisiting the Raw after capture with as much flexibility as the new <em><strong>histogram-way</strong> </em> because too many film-like decisions were made during capture, and therefor the resulting Raw is compromised, compared to a maximized Raw that can be uncompromisingly reinterpreted on demand any time after capture?</p>

<p>"<em><strong>Let the snow fall where it may</strong> </em> -- adjust it to your satisfaction <em>later</em> it in the lightroom"?</p>

<p>.</p>

<p>Peter: yes, if you use expose-to-the-right (ETTR) then the zone placement is done in the raw processor, not in the camera. It is similar to the old saw, "Expose for the shadows, develop for the highlights" (or was it the other way around? I could never remember). So when you expose, you optimize for maximum dynamic range, to keep as many options open for later as possible. When you process, you "place" the zones, realizing of course that you can alter the tone curve as needed.</p>

<p>There's even a raw processor called LightZone that lets you think in terms of zones when you process.</p>

<p>The problem with ETTR is that it then gets out of hand and becomes another technical cult. All sorts of processes are discussed on how to really get the maximum dynamic range, and are you getting the maximum dynamic range, and so on and on. Like many other technical discussions in photography, it has an allure that leads photographers into discussing it rather than practicing it.</p>

<p>I didn't read all the other replies, but I will say this.</p>

<p>It is quite acceptable to include specular highlights in photographs. If the algorithm always preserved detail in the brightest regions of the image, then we would lose too much in the shadows. In my experience, the Nikon metering does an great job of balancing these competing desires. If it's no quite right for a given situation, I just dial-in some exposure compensation or go to manual exposure.</p>

<p>If your Nikon system automatically meters for optimal dynamic range I'd encourage its use together with a check on the histogram. Clipped highlights are out of workable information range, and unless they're spectral highlights, should be avoided. To others posting on this thread in favor of intentionally overexposing RAW capture just to rescue it in post processing, are you the ones who love to spend lots of time on the computer, in order to justify shooting RAW?</p>

<p>.</p>

 

<blockquote>

<p>Earlier: "<em>... To others posting on this thread in favor of intentionally overexposing RAW capture just to rescue it in post processing, are you the ones who love to spend lots of time on the computer, in order to justify shooting RAW? ...</em>"</p>

</blockquote>

<p>Howard, I don't read anyone as advocating that anyone should carelessly or otherwise mis-expose any capture. </p>

<p>I see our exploration here as whether or not to previsualize our end-zones (so to speak) for immediate Raw capture as we did for immediate film capture, or instead to switch our capture thinking to NOT previsualize our end-zones, and instead capture maximum dynamic range over noise for immediate Raw, and then later use our Raw development software for expressing our output previsualization end-zones.</p>

<p>In other words, capture snow with detail because the camera can, but then later we can develop with washed out snow if that was our previsualization intention.</p>

<p>There is no right or wrong here, only choices. </p>

<p>If we want specular highlights or snow without detail, do we do that during capture as we did with film, or do we now let digital capture get all the detail in Raw because it can, then wash out that detail after capture to satisfy our original artistic expression whims? </p>

<p>There seems to be a voice calling for "because the camera CAN capture everything, we SHOULD let the camera capture everything". Hence the remark that if we don't want to PRINT everything, then we'd tune out zones <em>after capture</em> -- a new photographic opportunity provided only by modern digital Raw capture.</p>

<p>I'm not expressing a vote one way ot the other, only identifying our choices -- to be more aware.</p>

<p>I think I've got it. I think Kuryan expressed it well, also. What do others think, and more importantly, what do others DO?</p>

<p>.</p>

<p>Do you really want to use the "expose to the right" rule on EVERY photo?</p>

<p>How about a photo of large piece of navy blue fabric. If you "expose to the right" it's going to turn from navy blue to sky blue. Is that what you want? How about a photo of a dark-skinned lady in a long black gown against a dark background. Do you want her gown to look light gray and her skin to turn beige?</p>

<p>"Expose to the right" is a technique. As with any technique, you have to understand its limitations so you'll know when to apply it and when to use another approach. If photography were about blindly following rules, we could program robots to go out and take our images while we sleep in and enjoy a leisurely breakfast.</p>

 

<p>.</p>

<p>Dang robots stole my copyright while I was sleeping! =8^o</p>

<p>.</p>

<p>[[To others posting on this thread in favor of intentionally overexposing RAW capture just to rescue it in post processing, are you the ones who love to spend lots of time on the computer, in order to justify shooting RAW?]]</p>

<p>It must take a lot of work to so completely not understand the subject, the discussion and how it applies to photography. </p>

<p>It doesn't take a lot of work to be a troll though, and that was demonstrated very well.<br>

Bravo.</p>

<p> </p>

<p>.</p>

<p>Now, now ... I think Howard just falls into the category of:</p>

<blockquote>

<p>"digital photography okay,<br /> -- computer geek life <em>not</em> okay"</p>

</blockquote>

<p>... and I GET that!</p>

<p>The thread really begs us to become aware of the additional challenge of becoming a slave to the technology ... or becoming master of it.</p>

<p>Without exploratory discussions where we find everyone's fears, we've never gonna find how to climb out from under the technobabble and new edicts (ALWAYS EXPOSE TO THE RIGHT) and learn how we would decide for ourselves, and why. Hence, I can see reasons to ignore the histogram ETTR rule, and instead expose in ways that others would see as too far to the left or too far to the right -- but that's where <em>I</em> want and see my photographic communication!</p>

<p>Harvey, I imagine you'd like everything after the shutter release action to be out of your thoughts, to simply accurately reflect the decisions you made before shutter release, and to not have to revisit and tweak your captures afterward, right?</p>

<p>Others, including myself, I imagine we wonder if there might be an advantage to having an "accurate", unflavored Raw capture that does not reflect artistic exposure decisions <em>yet</em> , and then only later handle those artistic decisions <em>after capture</em> in post processing, whenever we want to, including making a variety of opposing decisions we could never had tried years ago when stuck with film that could only be developed one way, and one way only.</p>

<p>Harvey, I think you'd see that post processing "demand" as painful and unrewarding. Right?</p>

<p>So, in response to Jacob's opening question, we have at least two camps:</p>

<blockquote>

<p>- all artistic decisions happen before shutter release, all subsequent processing and print out steps just accept and presume defaults, any reinterpretations that cannot get what they want form the original capture require reshooting</p>

<p>Versus:</p>

<p>- all capture decisions are for broadest technical capture accuracy, and then artistic decision making can come <em>after capture</em> , whimsically, on demand, whenever, differently with each revisiting ... though "defaults" might be okay, also.</p>

</blockquote>

<p>Have I got it? Yes, no, maybe? Other?</p>

<p>.</p>

<blockquote>

<p>How about a photo of large piece of navy blue fabric. If you "expose to the right" it's going to turn from navy blue to sky blue. Is that what you want? How about a photo of a dark-skinned lady in a long black gown against a dark background. Do you want her gown to look light gray and her skin to turn beige?</p>

</blockquote>

<p>They won't "look" anything because it's just the raw image that's exposed that way. They'll "look" like whatever you choose to make them "look" in the raw processor. Default raw processor settings may well make them "look" very light, but you adjust the controls until they "look" they way you want them to.</p>

<p>How is this any different from zone placement in chrome exposures? If you shoot chrome and decide to place the black gown in Zone V, it will look medium grey. That's your choice - who am I to say you absolutely must place it in Zone II? All that ETTR does is defer the zone placement to the processing stage rather than the exposure stage.</p>

<p>By choosing ETTR, you can decide to place the dark gown in Zone II and you will not get posterization. If you had chosen an exposure that favored a "left" histogram, placing in Zone II might cause blotchy shadows.</p>

<p>Oh, and about always using ETTR? I don't. When I'm doing street shooting, I don't, because it slows me down. I just accept what the matrix meter decides. I do use ETTR when I'm shooting from a tripod and I have the time, because it improves shadow noise.</p>

<p>Another way to think of ETTR is that by increasing exposure, it's basically equivalent to decreasing ISO. That's why most ETTR practitioners only use it on the base ISO setting. It doesn't make sense to use it on a higher ISO, because you can achieve the same result by decreasing the ISO.</p>

<p>One more thing and I promise I'll shut up. To answer, or at least address, the OP's question: I agree with the many other posts that have pointed out an autoexposure system that always suppresses blown highlights won't be optimal. You have to let some highlights blow. It's a case-by-case decision.</p>

I think some posters are making this more difficult than it needs to be. I agree with the OP and have suggested this sort of thing a number of times before. It should be a relatively simple process to have a setting which allows you to capture ETTR or non-ETTR (i.e. situation normal) for those who whine that they don't want to do ettr all the time (or those who have no understanding of ettr - such as the blue fabric poster). On the matter of specular highlights, you could have a menu setting which allows the user to set a percentage cutoff for highlight clipping. That is, say, 1% of the scene clipped, or whatever. You could also simply get the in-camera processing to jpg to scale back the exposure by the appropriate amount so your jpgs wouldn't be washed out.

<p>

<blockquote>

<p >They won't "look" anything because it's just the raw image that's exposed that way. They'll "look" like whatever you choose to make them "look" in the raw processor. Default raw processor settings may well make them "look" very light, but you adjust the controls until they "look" they way you want them to.</p>

</blockquote>

<p >It's a great technique to use when you need it, but it's not an approach that I have the time or desire to apply on EVERY exposure. Who has that kind of time? In most cases you can "get it right" in the camera.</p>

<p > </p>

<p >Further, digital sensors are not all-powerful. You might have to overexpose some highlights in order to save some shadows. By following ETTR as a rule, there will be situations where you LOSE shadow detail because you refused to clip a highlight or two.</p>

<p > </p>

<blockquote>

<p >How is this any different from zone placement in chrome exposures? If you shoot chrome and decide to place the black gown in Zone V, it will look medium grey. That's your choice - who am I to say you absolutely must place it in Zone II? All that ETTR does is defer the zone placement to the processing stage rather than the exposure stage.</p>

</blockquote>

<p > </p>

<p >I think it's more similar to zone placement on black and white film, for two reasons. First, as you know, positive film has such a narrow latitude that you pretty much have to expose it where you want it. It's not really practical to overexpose slide film by two stops in order to capture shadow detail. You'll either need to bracket exposures or use split ND filters in order to register detail in a high-contrast scene. Second, the narrow latitude of positive film is an much a tool as it is a limitation. Black shadow areas look perfectly beautiful in a chrome; there's no posterization effect to worry about!</p>

<p > </p>

<blockquote>

<p >By choosing ETTR, you can decide to place the dark gown in Zone II and you will not get posterization. If you had chosen an exposure that favored a "left" histogram, placing in Zone II might cause blotchy shadows.</p>

</blockquote>

<p > </p>

<p >I guess I'll have to admit some ignorance here, but when you darken the image in the RAW file are you not losing some bits in the process?</p>

<p > </p>

<p >It's too bad that Rembrandt didn't practice ETTR. He could have eliminated those distracting shadows! :)</p>

<p > </p>

<p > </p>

<p > </p>

<p > </p>

</p>

<blockquote>I guess I'll have to admit some ignorance here, but when you darken the image in the RAW file are you not losing some bits in the process?</blockquote><p>

 

Not really. You may end up with 'empty' bits in the highlight end of the image, but this is what you would have had if you had exposed "normally" instead. ETTR when done correctly will give you the exact same image but with far less noise in the shadow regions.

<p>None of this is strictly relevant to the Nikon Forum and the thread is showing symptoms of turning into yet another endlessly circuitous argument in which respondents debate each other rather than replying to the original poster. This discussion is being transferred to the Casual Conversations Forum.</p>

<blockquote>

<p>If this is true, wouldn't it be a great feature to have the camera do this for you, e.g., automatically chose the correct amount of exposure compensation? What am I missing?</p>

 

</blockquote>

<p>As Dan Brown already noted, if there are specular highlights (e.g. bright reflections off glass or other polished surfaces) or actual light sources within the frame, then you would seriously underexpose the rest of the image by adjusting the exposure to <strong>not</strong> blow those highlights.</p>