Please help: M9 Exposure Problems

[Jamie Roberts]

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DR is DR. Fundamental to your sensor/camera system.

On this particular shot, I am only telling that it displays the whole range of possibilities one has with an M8. This is what this camera can do and nothing more.

 

Hmm. I think we almost totally disagree (though it may be just a perspective or language thing...the web is tricky sometimes)... so for the sake of discussion, not argument, I'm going to try to address your points.

 

So on your shot, you are not displaying the range of possibilities one has with an M8

You are displaying your interpretation of the values of that particular shot.

 

DR is DR, as you say, but it changes systematically, so sometimes you have more DR than others. DR coming off the sensor is what DxO is at pains to measure, and it changes due to noise (and thus effectively ISO), heat, and so on.

 

Let's call this potential the potential camera DR, before the system writes a raw file. Once you take your non-gamma adjusted, linear, non-color-space bounded raw file into the converter, a number of things happen (and they happen differently, depending on the converter):

 

• they are mapped into a gamma / luminance space, which affects the overall brightness of the image
  
• tonal values are mapped into a contrast curve (depends on your raw converter)
  
• they are mapped into a colour space, which affects the gamut of the colour
  
• noise reduction is added (depends on your settings)
  
• sharpening is added (depends on your settings)
  
• blackpoint is calculated (depends on the RAW converter)
  

All of these, pretty much, can affect the DR of the image. And you--as a viewer--of course, are now limited by the DR your monitor is capable of displaying in much the same way you are limited to seeing colours that can be displayed.

 

With me so far?

 

Let's take noise and blackpoint / whitepoint, or contrast curves, which are easy to use and generally available in every raw converter. When you take your RAW file and tweak exposure up or down, you are moving the "blackest blacks and whitest whites" through the interpreted range of your system settings, which means blackpoint and whitepoint and the contrast you've applied.

 

If I'm shooting at ISO 160, the potential, off the sensor range of the M9 is about 13 stops if you can believe DxO. But depending on how I'm processing that, I wont see or display all of them.

 

And in fact, I can't print all of them. I need to compress the DR to something printable.

 

So DR is dependent on the chain of things, which starts with the exposure, and that's why it's important to get it right in camera. Highlights with digital are more fragile than shadows, so when they're important (as in meaningful to the image) it's important to maintain them in capture.

 

Now, from my experience with the M9 (so far), I'd say that on a typically exposed RAW file, at ISO 160, I have almost 5 stops (in total) of post exposure latitude in the shadows before noise prevents further changes.

 

But I have, at most, only a stop or two in the highlights before they are unrecoverable. So for most cases, an incident reading, or a meter reading which approximates that, will be best; I try to allow for those 2 stops in important highlights in capture and let the shadows fall where they will, knowing I'll be doing something to them for print anyway!

 

What YOU can do is decide where you want to focus in terms of detail/luminosity. If you want the skies for whatever reason, you underexpose by little, if you want the trees you overexpose. By doing so you shift left or right the luminosity levels your camera can capture, but on the other hand you cannot do this without consequences. Besides your adjustments lie within a very small +- 1 stop a bit more?

My capture adjustments lie in about 2 stops on the highlight end of things; my post adjustments on the shadows are ISO related, because DR there changes as ISO increases.

 

If I can quote my old photography instructor, digital compression of DR is commonly is an "expose for the highlights, print for the shadows" sort of thing --again, because highlights are fragile in terms of DR.

 

On my particular photo Jamie, you can't pull anything out of it. If you change exposure you will lose either shadows or light. If you want however, more trees or more skies, you won't avoid post besides this is why it is there.

If you want to print, you can't avoid post. And of course I can pull lots of any raw file with a tone curve or gamma change or colour space change, for that matter. Or I can clobber it. It depends what I want to do. But I can't resurrect highlights that are blown.

 

On a bribe's face, dress or whatever there are tools that can independently enhance (viveza2 i.e which is on this month's LFI btw).

Anything you can do with Viveza you can do with curves, pretty much.

 

If you don't want that, then use camera's lightmeter with it's strong center metering or your trusty incident meter and no need for pp. Besides, within church you won't find contrast like that where you need to play with exposure. Light is controlled and camera's DR is enough and can forgive even mistakes.

Here in Canada, churches are filled with very high contrast light (candlelit interiors with stained glass allowing direct sun shining through them, darkness in the winter by 4PM but setting sun streaming through a window, spotlights in darkness, etc... Light in churches is typically uncontrolled and most, if not all, camera systems are incapable of capturing the entire range of that light.

 

It's up to the photographer to decide where they're going to place the values you see. Again, typically this is a compression of the DR in the scene as read by multiple reflective readings. That's why incidence is so nice: light falling on things mimics the way you see them anyway.

 

Problems begin when one encounters conditions like Michael is describing. Oh and you can indeed chose to ignore histo, but you should not do this when both blinkies and distribution of them is high in your histos. And it doesn't mean that they are not there either.

Yes, there are more problematic shooting situations than an incident meter can assist with, mainly when you literally can't get to the light that's falling on a subject. But for DR, going from a dark candlit church through the outside into bright sunshine is more than any normal meter system can handle. You need to approach exposure and post to get what you want (you also often need to add or subtract light just to make the camera capable of getting a range of values effectively, but that's another post)...

 

Here's an example: a picture of the bride framed in a doorway at noon on a very bright day... her father (where she's looking) is inside the door. I want that shot. What do I do? There isn't a camera on earth that will capture that, and the auto-meter is going to give a range of DR values that will get it wrong, for sure. So you hold the highlights in the dress, and adjust the shadows (father's face in particular) in post... (sorry for the small file and weird crop; don't have time right now to show the whole thing, but it's an M8 CV21 shot...and notice I let the road behind the bride totally blow out... but if I hadn't adjusted exposure for the highlights, the DR of the scene is such that I would not have gotten anything of the father's face. As it is, that's a huge "digital dodge" to bring him out of the shadows.)

 

Or here's another one; candelit reception, face moving through a spot light on the dance floor. You have to hold the face in the upper quatertone of the resulting curve, and adjust for density and the shadow values in post for print (M8 noctilux)...

 

On neither of these shots did the histogram or the highlight blown indicators actually help, in the slightest. In fact, in capture. The histo really can't be "wrong" because it doesn't say enough to be "true or false"--but it's not helpful in understanding what's important (to the viewer and to me) in these shots.

 

But with a nice M9, the new noctilux or even the summilux 50 or 35mm, an expodisc to meter WB, and good available lighting I cannot imagine someone not be able to focus composing.

I'm not sure what you mean by this, but WB is also something that will fool the highlight indicators I work too fast for an expodisc, and prefer to just set the white balance by hand, knowing it, too, will likely change a bit in post

 

Sorry for the long diatribe--I'm sure you know all this stuff, and we're just mis-communicating (never happens on the web). And I hope it helps explain why incident capture and highlight capture is so important, and why I don't need to rely on the histo or the blinkies to make sure I have the shot I want.

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[diogenis]

Obviously you need to proof the whole chain when you want an end result, from monitor to printer.

I don't believe DR change. DR is fundamental of the sensor and basically is the ability of the sensor to transform photons to voltage as brightness levels change. Obviously heat and all that affects sensor performance as it does affect electronics, but there are tolerances. And we can't do anything to avoid them so this is not a parameter to think when composing.

 

All I am saying is that camera's DR -not what you do with a developer after that- which is directly controlled via aperture and speed as you don't have any other magic button to play is the most crucial part of the whole procedure. From then on, if you manage to get a decent file you can do whatever you want using viveza or C1 or aperture/LR. You can paint the color yellow if you like, but you always need a good file to begin with.

 

You are guaranteed of a good file therefore in highlights -if highlights are what you are after- if you can use your meter, or the camera's and all I am saying is that you can validate your results in real time using the blinking reds. The less blinks the better your highlights. The limit of the highlights to 0 or close, secure you good preservation of everything. In the end it all boils down to choosing an f/stop and speed. Obviously there are cases where a particular scene may need more DR than what your camera supports. Then you need to choose what you keep against what you sacrifice, and there is nothing else you can do either.

 

I also trust auto WB of my camera except when under artificial light. I need accuracy there, because once you leave your scene, bye bye WB. You will never be able to reproduce color temperature again. Also, I don't want to mess with gamma, curves, blackpoints, brightness and all: I don't find a reason to do so. This is where we differ.

As an example, on my first pic again all I needed was a correctly set WB. If I start retouching shadows and all the result will be something different. Just as if I shoot a night shot using flash. I hate the intrusiveness of flash, how it affects colors and the worst the shadows they create. I hate that.

[Jamie Roberts]

{snipped} Also, I don't want to mess with gamma, curves, blackpoints, brightness and all: I don't find a reason to do so. This is where we differ.

As an example, on my first pic again all I needed was a correctly set WB. If I start retouching shadows and all the result will be something different. Just as if I shoot a night shot using flash. I hate the intrusiveness of flash, how it affects colors and the worst the shadows they create. I hate that.

 

No, it's not where we differ at all. You mess with a raw file's gamma by putting it into a raw program; all raw developers have contrast curves, Lightroom applies a black point based on the data in the RAW file, and WB is something, in particular, you *can* get right in post when it's almost impossible at the scene. In other words, when you open the file you've already messed with all that stuff A little more messing is usually necessary to get it right for print, is all. And all your camera does is most basic of indications for exposure, and they're often (if not always) totally wrong or not helpful.

 

Same with flash.. if it looks like you used flash (with the shadows and things you hate) then, with respect, you're not using flash correctly. You can easily use flash without inducing harsh shadows or colour casts, but you have to know what you're doing.

 

But producing a good print (the end goal for me) always requires some post. It's the nature of the beast.

 

We're arguing about different stuff for different results, sorry! YMMV

[diogenis]

When you dont want to mess with these things, raw developers begin with neutral settings. Because you still need something to open your files . Now, when you start messing with them is what I don't like, partly because I lose control: too many parameters. I can tell it an be creative and it sure is fun to play and sometimes it might be the only way to over saturate colors to enhance the moment. ok with all that, fine with me.

 

Flashes can be very intrusive, as well as very necessary at some cases. I am not using them. Sumilux lenses are very fast anyway.