How I prevent blown areas

This is a discussion on How I prevent blown areas within the Do's and Dont's forums, part of the Photography Tips category; I read the post on blown out whites so I thought I would give a few tips on how I deal with this issue pre ...


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  1. #1

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    I read the post on blown out whites so I thought I would give a few tips on how I deal with this issue pre shoot.

    A simple procedure that can be done with any DSLR

    I like to shoot in aperture priority or manual so I'll use this for an example.
    Set the aperture you prefer and choose to meter the light via spot metering on Nikon or center on Canon while in aperture mode.
    Point the camera at the brightest spot on the scene.
    Say for instance you chose f/4 and the meter decides an exposure of 1/500th.
    I change over to manual and stay at f/4 but I will double the exposure speed or increase it by half, in other words 1/1000th or 1/800th.
    I take a quick look at the preview function on highlights to see how the bright areas of an image appear and adjust accordingly.
    I shoot RAW so it's relatively simple to lighten shaded areas or tame slightly blown areas.

    Not sure how pros deal with this but I noticed that the D700 does a much better job in 3D matrix metering than my D80 does when it comes to blown areas.
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  • #2
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    Yup, that's basically what I do, but I don't push it that far, ie. I'll go instead of 1/1000 after the spot told me for 1/500, I'll do only a 1/600 or 1/700. That works for me, but it's more or less pretty good advice.
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  • #3

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    Yup, that's basically what I do, but I don't push it that far, ie. I'll go instead of 1/1000 after the spot told me for 1/500, I'll do only a 1/600 or 1/700. That works for me, but it's more or less pretty good advice.
    Good to hear I'm somewhat in the right direction, I learn by experimenting and if I find something that works I'll share it.

    Had a look at your site, well balanced portfolio and the B&Ws are fabulous, I love them!

    Thanks
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  • #4

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    Quote Originally Posted by reyvee61 View Post
    Point the camera at the brightest spot on the scene.
    Say for instance you chose f/4 and the meter decides an exposure of 1/500th.
    I change over to manual and stay at f/4 but I will double the exposure speed or increase it by half, in other words 1/1000th or 1/800th.
    The meter gives you the exposure that results in middle gray tone. If you meter the brightest part of the scene the meter tells you the exposure that will result in that part being middle gray. Increasing shutter speed decreases exposure, resulting in tones darker than middle gray. This is fine if you want the brightest part of the scene to be middle gray or darker.

    If the brightest parts of the scene are white or brighter than middle gray, I normally want them to appear that way in the photos. For instance most brides won't appreciate their white wedding dress looking middle gray. When I meter a white dress I know the meter is going for gray, so I over-expose a stop or stop and a half from what the meter says by cutting the shutter speed in half. 1 to 1.5 stops brighter than middle gray is closer to white, yet still well within the safe zone for avoiding any blown out whites.

    The key is knowing the dynamic range of your camera and processing. In general dynamic range is the difference in stops between the brightest parts of a scene and the darkest parts. The scene has a dynamic range, and the camera/processing has a dynamic range. If the scene's dynamic range is less than the camera's the photo will be low contrast; mostly gray tones, no solid black or white. If the scene's dynamic range is more than the camera's some of the details in the very brightest and darkest parts of the scene will be lost. As far as I can tell people have varying definitions of dynamic range. Some folks consider the entire range of tones from solid white to solid black. I'm mostly only concerned with the brightest and darkest gray tones in which my camera will still retain 100% of the detail. I want to make sure all important details fall within this range.

    The Zone System is a method of predicting and planning for tone placement in the finished photograph. It was invented for film, but the concepts are useful for digital too. Here's a google link to numerous articles: http://www.google.com/#hl=en&source=hp...tem+for+digital

    Edit: I also disagree somewhat with the statement in the original post. It's far too general. Blown out white = white with no details. I could come up with a list of hundreds of thousands of excellent photographs from both film and digital that contain solid white areas without detail. High key portraits often utilize detail-less areas of white. I would rephrase it something like "Try to avoid unintentionally blowing out the whites."
    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt

  • #5
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    I agree completely with Peach - not that all of my exposures are perfect (they rarely are ), but the issue isn't "incorrect" exposure, but rather where and how to expose. I always find the idea of an "incorrect exposure" kind of ironic.

    I'd suggest getting very friendly with your camera's spot meter. If you camera does not support spot metering mode for whatever reason, get a spot meter.

    Exposures are all about tonal relationships. Like Peach said, all the meter knows is middle grey. Where you expose from will be middle grey - or a color which has middle luminosity - but we'll pretend everything is b/w since we're talking about exposure which is ultimately tonal relationships.

    If another another region is 1 stop darker, that region will be half as bright as the area you exposed off of. Likewise, if yet another region is 1 stop lighter, it will be twice as bright. But you prob already figured that. The point is that there is no "right place" to meter, and that by choosing where you meter from will determine where everything else falls into place. Ansel Adams broke up the continuous tonal range from no detail black to no detail white into eleven discreet steps, each step represents 1 stop.

    (NOTE: When I speak of "stops" I am really referring to equivalent exposure, so you can either stop up/down your lens or decrease/increase shutter speed.)

    While the processing aspects of the zone system don't directly apply to digital, the exposure end does. The thing about the zone system and understanding it is that nothing "belongs" in any "particular" zone. There are certain rules of thumb about tones that we are very familiar with, such as anglo skin being in zone 5-6, african skin in zones 3-5, asphalt in zones 2-4, concrete zones 4-6 ... but that is only because we expect certain things to be reproduced a certain way.

    However, you can certainly render asphalt lighter or darker. The key to exposure control is to use manual exposure.

    Pretend that you are on the 32nd floor in a manhatten office buildind. You are struck by the contrast between the dark street below and the tall, white buildings on either side. Lets say that you really want the street to be nearly pure black (zone 1) and the buildings to be white with significant detail (zone 8). What you would do is point your camera or meter to the street, remembering what the meter says is always Zone 5. Lets say it reads 1/60, f/8 off the street. Next you'd aim the meter at the buildings lightest part, and take not of what the exposure is. Let's say it reads 1/1000, f/8.

    So now you have to make a choice. You know that your scene has 4 zones (or stops) of range from the buildings to the street. if you chose to just meter off the street, the street would be at Zone 5, the middle of the range - but you can always make it darker in post, right? But then if you took this exposure, the buildings would be at zone 9, which is "white with little detail" or in this case, "blown out". This is because the buildings are 4 zones brighter than the street (4+5=9). If you exposed the street at Zone 1 (-4 stops from where the street was metered), where you want it, then your buildings will fall into zone 5 (again, since they are 4 stops "brighter" than the street). But you wanted them to be much lighter to better reflect what you saw in the scene.

    Likewise, you can place the building at zone 8 by increasing exposure by three stops. But remember that the street will follow suite and will also become lighter. If you just metered off the buildings then the buildings would be at Zone 5 and the street at zone 1, this is where you want it the street, but getting the buildings brighter would require a significant amount of post processing. By placing the buildings at Zone 8 then the street will become 3 stops brighter as well, and be placed at zone 4, this too would require a significant edit to get the street to Zone 1, where you wanted it. (If you're confused about where I came up with these numbers, it's just simple addition and subtraction, starting at Zone 5 - the zone that the meter "sees" everything - don't be scared off by this, if you're confused it'll just "click" and you will understand it, I promise)

    In all cases, you want to avoid having to make extreme edits in post. Because you visualize the street being nearly completely black, and because it's easier to remove detail than to put it back in, you'd want to side with the darker end of the zone system to avoid blowing out detail where you want it - in the buildings. With this in mind, it would be better to to place the street at Zone 3 and the buildings at Zone 7. This will give give you plenty of detail, while only being a couple zones off from where you want the hilights and shadows to ultimately be.

    So, instead of just metering off the buildings or the street and exposing from there, you'd want to meter off the buildings and increase exposure twice or off the street and decrease exposure twice, doing either will place the buildings at zone 7 (2 stops more than how they were metered) and the street at zone 3 (two stops less than how it was metered). To achieve this while still maintaining DOF at f/8, the correct exposure would be 1/250 f/8, or 2 stops darker than 1/60 (the street) or two stops lighter than f/1000 (the buildings). Once in photoshop (or whatever you are using) you'd make the shadows darker and the hi-lights lighter using the curves tool in order to maintain detail. The curves tool can be translated also into zones 0-X, too but that's another topic.

    I did a terrible job explaining this, and it really isn't that complicated in practice despite that it's hard to explain on paper. After writing this I kind of wish that I referred you to another place because I'm sure that others could explain it better... Please feel free to ask questions and I or someone else I am sure will be here to clarify. The big thing here is that exposures are about relationships rather than about "right" or "wrong".
    bear with me. i don't have an escape button...

  • #6

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    One of the coolest things about digital for me is the histogram. Exposing and checking the histogram takes me a lot less time than determining the scene's dynamic range, calculating the processing plan, exposing, and then writing out a label for the sheet/roll so I knew what to do when I developed it weeks later. The meter displays the exposure settings in text for middle gray, and makes me do the thinking. The histogram shows me where black and white and everything in between are in a visual representation that's almost instantaneously interpreted. It's very easy to see if parts of the image are solid black or solid white. Coming from the traditional darkroom it's like being able to very accurately assess the exposure on a neg before any development is started (if you are shooting raw).

    http://www.cambridgeincolour.com/tut...istograms1.htm

    http://www.luminous-landscape.com/tutorial...ose-right.shtml
    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt

  • #7
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    Wow, thanks for the links. Time to start experimenting.

  • #8
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    Peach - being new to digital capture, and in light of your second post on SNR would you suggest that I leave the camera at +0.25-0.5 ev and process everything at -0.25-0.5 ev?

    QUOTE (luminous landscape tutorial)
    Also be aware though that by doing this you are in fact effectively lowering the ISO used to capture the image
    Of course those familiar with film this is practice nothing new...
    bear with me. i don't have an escape button...

  • #9
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    Being an old codger, I learned to shoot using the zone system. A camera is going to meter at zone 5 ( or there about), zone 7 is about as white as you can go with out loosing detail. I meter the brightest area bump up two stops if I want it white with detail, and pull the trigger. Plus I'm a firm believer in using the histogram.

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  • #10

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    Quote Originally Posted by twinkle_turnip View Post
    Peach - being new to digital capture, and in light of your second post on SNR would you suggest that I leave the camera at +0.25-0.5 ev and process everything at -0.25-0.5 ev?

    QUOTE (luminous landscape tutorial)
    Also be aware though that by doing this you are in fact effectively lowering the ISO used to capture the image
    Of course those familiar with film this is practice nothing new...
    [/quote]

    With film the problem is lack of density: under exposure with neg film shadows and over exposure with positive film highlights. If there is no density there is nothing that can be recovered. Theoretically too much density can be dealt with, although in the real world there are limits there too. For instance with neg film I can try to burn in the highlight details from too much density, but there's no way to recover shadow details from clear film. With neg film it's okay to always overexpose a stop because that will almost always fall well within the exposure latitude; it helps insure shadow detail and it's not going to cause problems with the highlights.

    With digital there are potential problems with both shadows and highlights. Anything that's off either end of the histogram is either going to be solid white or solid black with no details possible to recover. With a high dynamic range scene setting exposure comp to +0.5 could cause some loss of highlight detail. So I assess each situation individually. As Mac said, I am also a huge fan of the histogram. I like to see the histogram more on the right, but I don't want blown highlights. Depending on the scene/subject and lighting that might be a normal exposure, or a +0.33 exposure, or a +1 exposure. I almost always use M and Av. If setting exposure comp or flash comp to +something is working in a particular shooting situation I'll leave it there, but the histogram makes it easy to check and reassess exposure whenever the lighting or scene tones change. I actually don't pay much attention to the meter these days. Most of the situations I shoot in I've got a pretty good idea of what the exposure should be, so I set the camera, take a test shot, check the histogram, and adjust from there. The histogram gives me most of the info I want in one quick test shot that I used to have to take several minutes spot metering highlights and shadows and doing math and taking notes.

    Expose to the right is a raw thing. I'm not sure how well it would work with the camera set to jpeg. I haven't liked any in-camera processing software I've ever used so I don't shoot jpeg. In earlier versions of Adobe Camera Raw I did often find myself adjusting the exposure setting by -0.50 to -0.75. The most recent versions of ACR and Lightroom offer more controls, and I don't always use the exposure slider these days. A lot of times I find myself leaving my brightest highlights where they are, and using the curves control to darken the shadows and midtones. With film and the zone system I could expand or contract the highlight side of the tonal range. With digital I can expand or contract the highlight side, the shadow side, or even part(s) of the tonal range in the middle. I love it!

    One thing to keep in mind when shooting raw. The histogram is based on an in-camera processed jpeg. That means in-camera processing parameters will affect how the histogram looks, but that is not how the raw file will look. For instance higher contrast, saturation, and sharpening can show blown out highlights on the camera histogram that won't be a problem with the actual raw file. I set my cameras to the most neutral, most processing turned off processing parameters as possible. That way I get the most accurate histogram possible. Even so I usually find that I can recover highlight detail in the raw processor that the camera histogram showed as blinkies because they are just slightly over the edge of the histogram (in camera).



    "I donít use an exposure meter. My personal advice is: Spend the money you would put into such an instrument for film. Buy yards of film, miles of it. Buy all the film you can get your hands on. And then experiment with it. That is the only way to be successful in photography. Test, try, experiment, feel your way along. It is the experience, not technique, which counts in camera work first of all. If you get the feel of photography, you can take fifteen pictures while one of your opponents is trying out his exposure meter." -Alfred Eisenstaedt


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