expose for shadows, develop for highlights now inverted on digital?

<p>I'm reading ansel adams' book "The Exposure" and was wondering if the old adage had now been inverted. Adams explains that on film one exposes for shadows and then can use developing techniques to bring back detail that may be over exposed by adjusting developing techniques. Tones can be compressed to pull exposure values of XI or even X down to a more reasonable VII or VIII. and this process doesn't affect the lower valued zones as much, leaving the zones of III and IV more unaffected. Thus expose your shadows correctly and pull down or expand your highlights as needed. <br>

I'm wondering if this is now essentially inverted. In other words, because of the precipitous shoulder of digital sensors, if it is better to expose the highlight areas better and leave the shadows to fall where they may, and then adjust them in post processing as adams would have done in the darkroom. So for instance, on my Nikon, i could use the d-lighting, or layer masks and exposure compensation for a very targeted approach as well as contrast adjustments. But because of the destruction of detail in overexposing on a digital sensor, if this might be the procedure that would generally yield the most control/best results on digital exposures. Just wondering if any one had a better theory or perhaps saw a fatal flaw in this argument. thanks for your time.<br>

dan</p>

<p>http://www.luminous-landscape.com/tutorials/expose-right.shtml</p>

<p>pretty much, yes.. you cannot compare digital capture with film. A sensor is not like film. They are both light sensitive but that's about it.</p>

<p>Treat digicams more or less like tranny film. That is, expose for the highlights. In digicams, this is now called expose to the right (that is, push the exposure to the right on the histogram). Just don't clip when you push to the right. ;-)</p>

<p><em>"Treat digicams more or less like tranny film. That is, expose for the highlights. In digicams, this is now called expose to the right (that is, push the exposure to the right on the histogram). Just don't clip when you push to the right. ;-)"</em></p>

<p>While I understand this argument I do not understand how to achieve it except perhaps in a few fortunate situations where the exposure curve is JUST right (i.e. flat throughout). We are seldom blessed with perfect exposure curves, in fact at just those times when I worry about getting the exposure correct, it is because the picture is particularly contrasty. In this case there will almost certainly be a tall peak on the right hand side of the curve (and most likely on the left, too.) Which, it seems to me would preclude pushing the curve further right without blowing even more highlights<br>

So my question is - how on earth does one push the curve further to the right without blowing more highlights in these circumstances? I have to say, my instinct is to do the opposite - deliberately UNDER expose to pull that excess of light pixels at the right hand side of the graph back to something reasonable. In fact I had originally believed that this is what "shooting to the right meant" (i.e. shoot having regard to the need to lower exposure and limit the chance for blown highlights.) But I have read quite a few posts that say the opposite as in the above post .<br>

PLEASE EXPLAIN BECAUSE I AM NOT GETTING SOMETHING AND OBVIOUSLY THE WORLD KNOWS MORE THAN ME - SOMETHING THATS NOT UNUSUAL , I FIND. :^)</p>

<p>Peter - I have found in my digital shooting the answer isn't always as precise as I'd like. Generally I agree with the concept of exposing for the highlights in digital, like transparencies, but some scenes don't seem to really work out with that approach. My suggestion, since it is digital, is to bracket your exposures and see how your particular gear and style responds, and use your findings as a basis for future shots. After all, it doesn't cost anything more, as it would in film, and you can have your results for analysis same day.</p>

<p>Peter, have you read the tutorial that Mark Sirota references? That should explain it for you, both the how and the why. Of course, if the subject brightness range (SBR) exceeds the dynamic range of the sensor, you have no choice but to clip one end or the other (or both) when making your exposure. In that case, make two -- one that preserves the right, one that preserves the left, and combine them into an HDR image. Many recent digicams actually automate this kind of bracketing to make it easy.</p>

<p>I believe, Dan, that you have it exactly right. Expose for the highlights and slightly underexpose when in doubt. Which is exactly what you're supposed to do with slide/transparency film, by the way. It is best to use the rules for slide film when shooting digital. Digital could be considered a "positive film", just like slide, because it is recording what is actually in front of the lens, not the negative of it. Because it's not recording the image like a negative film would, the rules are reversed. </p>

<p>Basically, in typical situations, expose so that a) the right "point" of your histogram curve does not flatten against the right side of the diplay and b) the blown highlight indicator (flashing black on Canon) does not appear. In portions of the image where the luminosity value goes all the way to maximum the channel can hold no detail at all, and there is essentially no possibility of recovery.</p>

<p>There are exceptions to every "rule," including this one. In some cases you can intentionally allow some highlights to go completely white as long as that is what you intend. For example, small spectral highlights can sometimes do this.</p>

<p>While overexposing the highlights on a DSLR may leave you with a complete and unrecoverable loss of highlight details, underexposure of the shadows can be a problem from which some recovery is possible. If your choice is between blowing the highllights and underexposing the shadows, it is probably a better choice in most cases to take care of the highlights at the time of exposure and try to recover the shadows in post. When underexposed your shadows will have two problems: there may be a great deal of noise and there can be some banding of shadow details. Neither of these are ideal, but they are "less bad" in most cases than losing highlights. In many cases a bit of noise in the shadows won't even be noticed in a print, and there are ways to minimize the noise and banding in post.</p>

<p>When faced with a really wide dynamic range scene you could handle it the way film photographs often did - use a graduated neutral density filter. With digital you also have another option which can sometimes provide even more control: bracket your exposure and combine the two (or more) version with masks in post-production.</p>

<p>Dan</p>

<p>Guys, I have seen the Luminous Landscape article but that is exactly what I am talking about ----look at the first set of curves - the nice rounded curve with a lot of mid tone content. (OK admittedly this would be a little boring as a photo as there would most likely be too much mid tone and too little dark or light contrast) but with a curve like this, <em>why on earth would you</em> <em>want</em> to worry about exposure or moving it to the right - something which with this curve you could in any event readily achieve with much more precision after the event in Photoshop.<br>

Lets, for argument sake, see the article re-written with a real world curve - spread out with a peak on the right hand side which is what happens when you take a picture (say) on a bright sunny day and have some sky in it or perhaps some shadow which has over influenced exposure producing clipped highlights. Could you move the curve to the right then. I frankly fail to see it. (Sorry I am just trying to understand the argument not be combative.)<br>

I do get the argument about merging pictures as a HDR image and can thankfully do that easily in Corell Paint Shop Pro Photo X2 as there is an automated HDR filter that will undertake the merge for you. But again this only works in some situations - as when you have had the forethought to carry a tripod so as to get the necessary steady double or triple shots at different exposures and when the image is a static one - not involving moving elements.<br>

Hmm perhaps I should have gottan that darn fuji S5 instead of the D200!</p>

<p>PS to my post above.<br>

Alternatively does this not mean that my original interpretation of the instruction to reverse the adage about "exposing for shadows and developing for highlights" is correct? <br>

That is to say does <em>this not really mean</em> when shooting digital, you should let the shadows come out <em>under exposed</em> in favour of having better highlight exposure as in digital its easier to retrieve too dark shadows than it is to retrieve too bright highlights.<br>

In other words, exposing to the right means pushing your curve further to the left in the knowledge that the situation can be better retrieved in post processing than if the opposite is done?</p>

<p>This seems much more logical to me than the other argument.</p>

<p>ok. now that i have that little conundrum a little more resolved, i have a follow up if any one has a good answer for me. ansel says that contrast is adjusted by the amount of developer added or removed from developing of the negative. and that this disproportionately affects the higher zones: the point being, that, essentially, one can fix one's shadow values, and then telescope or contract the range of the higher zones above that. Now, supposing that i chose a highlight in my photo or the most luminant area that i want to preserve detail in, and expose to have that in zone VII or VIII (very bright and at the threshold of holding detail and texture), and then because of the luminance values of the subject/scene that i am photographing, i find that the shadows in my picture are going to be a little brighter than i would like: i can adjust the contrast, and by increasing the contrast, deepen the shadows. Now, will it also push my highlights higher, and thus i need to compensate for this adjustment, or does it affect the highlights or shadows disproportionately more? The point, i guess, is where is the center of the "stretching"?</p>

<p>also, re: G Dan Mitchel: i think that this was exactly what i was thinking. that ansel says blown highlights on film are more recoverable on film whereas underexposed shadows are gone forever on film: the opposite is true on digital sensors and thus setting an optimal exposure for the highlights and then pp on shadows is the ideal way.<br>

but i'm interested to hear of information about the contrast increase/decrease compensation. For instance, say that i pick my highlights in my scene and want them to reproduce (in black and white) as a bright zone VII or VIII (which is about 80-90% luminance, if i can negligently ballpark it) but either way pretty white. Now for the sake of argument and the example here, let's say that that renders the rest of my scene about neutral gray at 18% and i want to make the scene more dramatic. So i also want to deepen those shadows. So i increase my contrast, say all the way up. That should, at the same exposure settings, deepen those shadows, but will it also then raise the luminance of the highlights on my sensor and screen? do i need to take off a little shutter speed or close my aperture a little to compensate a little bit for this adjustment? on film, it seemed like only the highlights were affected by contrast adjustments. <br>

thanks a lot for your responses.</p>

<blockquote>Guys, I have seen the Luminous Landscape article but that is exactly what I am talking about ----look at the first set of curves - the nice rounded curve with a lot of mid tone content. (OK admittedly this would be a little boring as a photo as there would most likely be too much mid tone and too little dark or light contrast) but with a curve like this, why on earth would you want to worry about exposure or moving it to the right - something which with this curve you could in any event readily achieve with much more precision after the event in Photoshop.</blockquote><p>

 

Peter.... The concept of 'expose to the right' is this:

You want to capture the brightest highlight that you want to retain detail in (so, basically excluding specular highlights) as close to the right hand side of the histogram as possible. You don't want to clip (that is, overexpose) anything important off the right side of the histogram. So in a 'normal' contrast scene, you want to expose say a face or whatever at the right edge of the histogram, but without clipping it. In post-production, you bring the scene back to a 'correct' exposure. i.e. the faces won't be bright highlights, but they will fall in the histogram where they would have had you not exposed to the right in the first place. So, you end up with the same image exposure that you would have had you normally exposed, but your shadows will have far less noise in them.<p>

 

Now, in the case of a high contrast scene, it is likely that the scene dynamic range will exceed your sensor dynamic range. So you are correct in asserting that you won't be able to push this exposure any further to the right. The only choice you get in this situation is whether to clip the highlights or clip your shadows.<p>

 

Hope that made sense.<p>

 

<blockquote>Now, supposing that i chose a highlight in my photo or the most luminant area that i want to preserve detail in, and expose to have that in zone VII or VIII (very bright and at the threshold of holding detail and texture), and then because of the luminance values of the subject/scene that i am photographing, i find that the shadows in my picture are going to be a little brighter than i would like: i can adjust the contrast, and by increasing the contrast, deepen the shadows. Now, will it also push my highlights higher, and thus i need to compensate for this adjustment, or does it affect the highlights or shadows disproportionately more?</blockquote><p>

 

Dan.... You can increase contrast in whatever fashion you like by drawing the appropriate curve yourself in photoshop. That is, leave the highlight to midpoint region of the curve linear, and pull down the shadow to midpoint region. Using lightroom makes this process really easy, but it is not too difficult to achieve in photoshop as well. Cheers.

<p>ahhh bernie. thank you very much. you've taken a lot of mystery out of curves for me. i always blundered through them but now have a more tangible grasp of them. thanks very much.</p>

<p>With film the issue is lack of density: shadows with neg film and highlights with positive film. Conceivably you can burn through too much density, but there's no recovering detail that's not on the film. With digital you have to worry about both ends of the scale. </p>

<p>Expose to the right:</p>

<p>http://www.luminous-landscape.com/tutorials/expose-right.shtml<br>

http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html</p>

<p>All well and good but my point is still this. The Luminous Landscape article seems to me to be disingenuous. With a tonal curve that looks like the one it is depicting, exposing to the right is easy. But why on earth would you want to bother in that situation? Neither the shadows nor the highlights are clipped. Noise at the shadow end should not be a problem with a curve like this and neither should clipped highlights.</p>

<p>I hear you Peter. I went back to shooting film 90% of the time because I got tired of dealing with these issues. It takes me longer to clean up noise and get nice contrast from my DSLR than it does to scan a 6x7 transparency which I end up doing little to no post-processing on.</p>

<p>Exposing to the right is okay, until you clip the highlights. Blank whites are impossible to salvage in jpeg. Clipped shadows are more salvageable. Of course, a full range of values without clipping on either end is the ideal. But if pushed in broad lighting I'd rather have noisy pulled up shadows than totally blown highlights. A better solution of course, is shooting RAW. Then proper exposure is somewhat less critical.</p>

<blockquote>All well and good but my point is still this. The Luminous Landscape article seems to me to be disingenuous. With a tonal curve that looks like the one it is depicting, exposing to the right is easy. But why on earth would you want to bother in that situation?</blockquote><p>

 

Peter... I've just had a look at the curve (didn't look at it earlier), and you are right that in that case there wouldn't be much to be gained in exposing to the right. But there also wouldn't be anything to be lost. And you would actually gain a little bit in reduced noise in the darkest part of the image, whether that is shadows or low mid-tones. But your point is taken.<p>

 

One extra thing to be said about that histogram, is that it is a gamma converted histogram (ie. it is from a jpg or tiff etc). The real raw data histogram as captured by the sensor, would be stacked up at the left hand end like nobody's business. So while most of those midtones end up in the middle of the histogram, they actually started out down at the low end. So there is still a benefit to be gained with this technique. But as will all these things, there are upsides and downsides, and ultimately one has to take this into account to determine what is the best approach.

<p>Dan, I don't know about the digital stuff to the extent y'all are discussing it here; but, Adams did not always overexpose and underdevelop. There were situations in which he did the opposite; although, if I remember right, one of his more frequent patterns was to underexpose and develop normally. (N-1 to N) or its converse (N to N-1).</p>

<p>I mention this because it occurred to me that it may not be the recording media, but your choices in response to the situation that was leading you in that direction. Maybe it would be helpful to look at the times when Adams decided that way, too. In "The Negative" he had several ways of doing it. </p>

<p>If I follow the general concept of the histograms thing right, above; Adams, too, would use compression or expansion of contrast when he was tinkering like this. I think part of the discussion of curves, above, is a computer mimic of this; seems like same idea, but different media. Anyway, "The Negative" by Adams will have more detailed examples.</p>

<p>If you are short on time, maybe the way to find something that looks like your question would be to cruise through the pictures; there were several in my copy that had notations about exposure and darkroom pushing or pulling for compression or expansion (like N-1 to N or N+1 to N-1, where N is normal development and the pluses and minuses represent adding or subtracting the equivalent of a stop's worth of light, but in the form of chemical exposure in the darkroom and not just in light exposure in the field).</p>

<p>He frequently recommended Overexpose/underdevelop model, because it is "safer" for capturing, but there were instances in which he noted the opposite. The driving factors were arbitrary and situational; main idea was that he would pick his subject and then push or pull everything else in order to render his subject in the range of grays he desired. His book explains his method better than I can. "The Negative." I'm sure that other one is a good book, too; but, I know there is a wider variety of examples in "The Negative." One of them will answer your questions.</p>

<blockquote>

<p>ahhh bernie. thank you very much. you've taken a lot of mystery out of curves for me. i always blundered through them but now have a more tangible grasp of them. thanks very much.</p>

</blockquote>

<p>If curves look odd simple levels adjustment is very obvious as you move the sliders under the histogram.</p>

<p>I usually just shoot RAW about one stop over jpg-limit. Recover highlights and there's a +1 bonus in the shadows without even touching them. Actually this is a "proper" exposure when you have post editing in mind - not that different from zone system. Shoot for post work, overexpose and underdevelop. Or perhaps I'm just a bit simple. ;)<br>

<br /> Also a matter of taste to some degree, I really don't like underexposing and adjusting muddy images.</p>

<p>I've always thought shooting RAW similar to shooting negative film. You can overexpose to get good amount of noiseless shadow detail. *More light is always better* if possible within medium boundaries. Also, RAW is your starting point from which you can make different interpretations. That's it.<br>

Of course negative can tolerate pretty massive amount of overexposure before totally blowing out and with b&w you can adjust development but this only changes the tolerance, not the principle. Extreme shadow/highlight recovery is not that fun in either medium (I do have a darkroom).<br>

There's no difference in making an edited JPG and wet printing a negative. It's just that work order is different. In the darkroom you edit while you print and tone but with digital you have already edited and you're left with the problem of calibrating everything so that the print process is neutral. And that's really fun isn't it. :)</p>

<p>Peter,</p>

<p><em>With a tonal curve that looks like the one it is depicting, exposing to the right is easy. But why on earth would you want to bother in that situation?</em></p>

<p>The theory is that exposing to the right reduces noise and improves tonality. In my experience you don't necessarily see or realize this unless and until you push an image hard in post processing.</p>

<p>Also: some of the confusion about exposing to the right could be eliminated by describing it in terms of a spot meter. Spot meter the brightest highlights you want to hold and place those near the right of the histogram. Let the remaining tones fall where they may. If you're using another metering mode your image may already be "to the right", or even horribly blown out, depending on what the meter decided.</p>

<p>Incidentally, I am a huge proponent of learning to use your partial/spot meter and relying on it whenever time permits. A lot of exposure problems disappear once you turn off dumb 'smart' metering patterns. Partial/spot also forces you to think about where the tones will fall in the scene and make intelligent choices about it.</p>