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Photography Question 
Henry W. Pyle
 

blown out histogram


I read something recently that gave me the impression that using a histogram to "see" if the exposure is correct, should not have anything "blown out" either on the right (light) side or on the left (dark) side of the histogram. When shooting, and checking the histogram, I often find that even if I am bumping up against one side of the histogram the other side is blown out. If I try to correct, then the other side is blown out. It would seem that I don't understand using the histogram or what it is telling me.

Bottom line is this: How do I use the histogram to make sure my exposure is correct?


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1/31/2007 8:52:53 AM

 
John Rhodes
BetterPhoto Member Since: 2/24/2005
 
 
  Broadwater Marina
Broadwater Marina
© John Rhodes
Nikon D70 Digital ...
 
 
Henry, From what I understand, you should try to expose as far to the right as possible without overexposing; that is, blowing out the brights. As far as being able to control both ends of the histogram, that may not be possible. Depending on the light in the scene you are shooting, there may be alot of shadow, even black, in the image which is going to result in a histogram that bumps up against the left side. For example, shooting at sunset with foreground objects that you want to appear as silhouettes.

Let me submit an example that actually bumps against both ends. The darkness of the silhouetted lighthouse on one end and the brightness of the headlights along the distant road. I exposed for the sky, and am satisified with the exposure, so that's what counts to me.

Just remember, if you blow out the brights or underexpose the shadows, you will likely not be able to recover any detail in those areas.

John


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1/31/2007 1:11:38 PM

 
Henry W. Pyle   John,

It always seemed to me that it was not always possible to do as I was led to believe, even though I know a good photograph usually has a wide tonal range. I really appreciate your response. Your gallery is fantastic. After seeing it I know that you know what you're talking about. And, I know just to make sure not to blow out my hilights.

Hope you and yours are doing well in Katrina country.

Thanks

Henry


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1/31/2007 2:02:18 PM

 
John Rhodes
BetterPhoto Member Since: 2/24/2005
  Henry, thank you very much for your kind comments. Also thank you for remembering Katrina. As you can imagine, many of my favorite places to photograph are not the same as they once were. The image I posted above sort of represents what we are experiencing. Notice the top of the lighthouse; bent, but not broken!

John


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1/31/2007 2:45:11 PM

 
Ariel Lepor
BetterPhoto Member Since: 9/8/2005
  I use helicon filter, and I can drag a brightness bar on the equalizer to change the right and left side separately.

Having said that, there are often times when you want a large dark or bright area in a picture.


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1/31/2007 4:45:42 PM

 
Brenda Tharp
BetterPhoto Member Since: 6/9/2003
  I'd like to add something to this discussion. While Ariel is correct, that sometimes you want a large dark or bright area, one always has to evaluate the size of those areas and how they affect the overall balance of the composition. Like anything else, the decision will be dependent on the scene. As for exposure, as John mentioned, there are times when you'll be overexposing hightlights, but if it's small headlights as in his lighthouse picture, who cares? Like the sun, it would be near impossible to get detail in those areas without losing the rest of the scene. We expect them to be overly bright, so it's acceptable and they are small proportionately in the frame. If you are bumping up against both sides of the histrogram, it's a good reminder to look at the light, the range of light, and decide whether it's going to work or not. In John's picture, it makes sense and it works; but if you had large areas of bright and large areas of dark scattered through the scene, such as sunlight dappling in a forest of trees, it could be a nightmare to expose properly. One more thing: if you notice a large area of pixels spiking off the top of the histogram - don't panic about that; this just indicates that in that particular tonal value, you have a lot of information - or your scene has a lot of tonal values in that range. This could mean that your picture would be 'flat' - i.e. not enough contrast to be interesting, but it's not as critical as those highlights.


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1/31/2007 9:45:24 PM

 
Henry W. Pyle   Thanks Brenda. Love your work.

I have a question about your last comment. If you have a spike off the top of the histogram, but you still have a broad range from left to right in your histogram, would your image still be flat?

Thanks

Henry


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1/31/2007 10:42:12 PM

 
Ariel Lepor
BetterPhoto Member Since: 9/8/2005
  You know, Henry, a histogram simply says how much bright and dark there is. It isn't a magic thing you can read to show exactly how the image will look. Your own eyes are a better judge if an image is dynamic or flat, overexposed or underexposed.


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1/31/2007 10:55:41 PM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  "I have a question about your last comment. If you have a spike off the top of the histogram, but you still have a broad range from left to right in your histogram, would your image still be flat?"


With the broad range, no. Or not usually, because who's to say you might actually end up with one.
What she means by flat is that tonal values (which could be the light/dark area or colors working together) are close.
Think of it as a medium gray suit with a light gray shirt, and maybe a tie for color. Nothing special about a gray suit, but if you change the shirt to white(nothing special about that either), you at least have the collar and the top part of the shirt to break things up. And a small area, like a highlight, to accentuate the tie.


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2/1/2007 12:40:22 AM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  P.S. What Ariel said made me think of something(disagree about the magic though) The histogram can really help if you haven't gotten used to judging how the camera monitor shows a picture. Take a series of increasingly under exposed shots and you can get several that if you don't compare any to each other, will look fine on the camera monitor. But print or show it on a comp monitor and see the grain like noise start to come out of the dark areas and the colors are lacking, then you'll see that it wasn't as good as it should be. But once you get used to knowing that when a shot is exposed right, then this is how it looks on the camera, then you need the histogram less and less.
It reminds me of trying to print black and white night scenes in the dark room. At first, under the safe light, the print might look fine. Until I turned on the room light and saw how pale the black areas where. I had to get used to knowing how a dark scene looked when it was done right. Saved on paper.


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2/1/2007 1:01:14 AM

 
Brenda Tharp
BetterPhoto Member Since: 6/9/2003
  Gregory, thanks for a great example of similar tonal values with the grey suit description. It's right-on; so if your histogram has stuff on the left and stuff on the right and a large spike in the middle areas it won't be a totally flat (no contrast) picture, but you'll have a large area that may be similar tonal values. This helps me when looking at a forest of green trees with green moss, etc. They may be too similar in tonal values, and need something else in there (like Greg's white shirt idea) to break things up and add interest. A great course to help you understand histograms is Ellon Anon's course offered here, at Betterphoto, if you're interested.


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2/1/2007 6:13:13 PM

 
Theresa M. T
BetterPhoto Member Since: 2/10/2007
  A histogram means little without the image, but the image is fine without it. In a nutshell, all the histogram means is that if it runs off the left, some pixels are going to be black and if it runs off the right, some pixels will be white.

If you photograph brown cheese in a grey corner with even lighting and no flash, you should get a nice histogram. Just about anywhere else and one end or the other will probably be clipped a little.

It is suggested by many sources that you want the bulk of the data to lean toward the right side. For most shots, if they are exposed properly, that is how the histogram will look. But, as pointed out above, it depends what you are photographing, and clipped on one end or the other (or both) isn't necessarily a bad thing.


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2/10/2007 2:36:19 AM

 
Raymond H. Kemp
BetterPhoto Member Since: 4/2/2004
  One of the biggest mistakes I see many beginning (and some non-beginning) photographers here make is not understanding how to properly expose an image!! In other threads I see way too much emphasis in shooting RAW as if that is some sort of cure for fixing bad images. It all starts the moment you push the shutter release and the proper exposure can mean the difference between a good photograph and an exceptional one. Many pro’s including myself use the histogram religiously to check our exposure ranges and there is a lot more to that than assuming that data to the right means a properly exposed photo.

Once I take the photo, chimping to see just the image is for the most part useless to me as far as exposure is concerned. I always have mine display the histogram. A quick glance at the histogram, increase or decrease my EV, shutter or aperture settings and presto I have an even better exposed shot the second time! Your little LCD display of the image alone will not give you the details to your exposure as a histogram will. It simply does not have enough capability to show the exposure range and color accuracy, period. How many times have you chimped your image and thought “hey that looks pretty good” only to later bring it up on Photoshop and realize that certain detail is blown out or too dark or the overall image is “muddy” because your brightness setting on your LCD was set to high giving the appearance the image exposure was good?

Once you master the understanding of your histogram a whole new world will open up for you when you get the image to Photoshop and use the PS histogram to work with your image.

I make my living shooting for several Emergency services magazines published out of California as well as several newspapers. I don’t have time to shoot, chimp, shoot, chimp. I need to shoot, check my histogram and make any immediate adjustments for in a few moments the action I’m shooting is gone. Spending a few days learning the value of a histogram made a huge difference for me and it will you too whether your shooting paramedics or landscapes.

Brenda recommended Ellon Anon’s course for histogram and that was the best advice in my opinion for this tread. If your serious about digital photography then learn to use one of the best tools right under your chin… the histogram.

Ray


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2/10/2007 9:38:32 AM

 
Henry W. Pyle   Thanks Ray for the comments. That is why I asked the question - to get a better understanding of what the histogram is telling me. I know it is one of, if not the most important tools available to me in digitial format, at least to determine proper exposure. Given Brenda's comments, I now want to know more about what it is telling me about tonal ranges. Am I correct in assuming that the histogram, properly understood, is giving me information about contrast (right to left) and tonal range (top to bottom)?

I would love to take the course suggested (and many others). I plan to do so in the future, but unfortunately I am currently unemployed.

Thanks again for the comments.

Henry


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2/10/2007 11:03:54 AM

 
Raymond H. Kemp
BetterPhoto Member Since: 4/2/2004
  You’re on the right track Henry. A histogram shows brightness values from left to right 0 (shadows) being the darkest and 255 (highlights) the lightest values. The middle is considered midtones. Since contrast is the variation between light and dark values the histogram would display how much tonal range is spread from your shadows (left) to highlights (right). Clearly the broader the range the more contrast. The top to bottom as you put it is the number of pixels with in each of the 255 line bars that spread across your histogram. The higher the pixel line the more value of that particular tone is present in the image. See how it works?

Wait till you see how you can use the PS histogram to improve your post production image! But first, you need a properly exposed image and your camera histogram is a great tool to get you in that direction. Anyone who is serious about digital photography needs to learn the principals of the histogram and how to incorporate it into thier work.

Good luck!

Ray


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2/10/2007 12:46:20 PM

 
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