| February 12th, 2007 03:20 PM | |
 LVE
Joined: Aug 1, 2006
Posts: 825 | Auto Modes - Manual Modes - Part 2
The Histogram
The histogram is a graph that is found on many cameras and in most all Software editing programs. This is a very important tool to use to analyze shots you take and to better understand the light distribution and how it affects the entire photo.
That histogram generates the graphic representation of a photo. The left hand side of the graph generated represents black or dark, and the right hand side represents white or brightness. Therefore, when looking at the graph the darker photo will be weighted to the left, and the brighter photo will be weighted to the right. When looking at the center of the graph, the mid tone brightness is represented in the center of the graph. The vertical axis indicates that pixel quantity existing for the different levels of brightness.
If the graph rises as a typical bell shaped curve, from the bottom left corner of the histogram, to a peak in the middle, and then descends from the bottom right corner, all of the tones of the scene are captured. If the graph starts or ends too far up on the right or the left or right vertical axis of a histogram, so that the “slope” looks like it is cut off, then the camera is cutting off data from those areas. Loss of some detail is inevitable when the contrast range is beyond the capabilities of the camera, a dark tones subject surrounded by extremely bright sky or water, for example.
When the histogram is heavily weighted towards either the dark or bright side of the graph, detail may also be lost in the weaker of the two areas. However, some scenes are not fully dark or light in tone. In these cases most of the graph and be on one side of the scale. Personally, I would rather always work with a slightly underexposed shot and edit rather than vice versa.
To render detail and highlight areas, control exposure so the slope on the right reaches the bottom of the graph before it hits the right vertical axis and drops off that side. If a scene includes the detail elements in shadow areas, manage exposure so that the left side of the curve slope reaches the bottom of the histogram before its crosses the vertical axis. In the the “real” world you can’t always produce a perfect histogram.
Always check the histogram after taking a shot and, if necessary, re-shoot using a plus or minus exposure compensation setting. You may also want to shoot again making changes to aperture and shutter speed settings. Then, look at the histogram settings each time, after each shot to evaluate the effects to the histogram, and thus potentially the final photo.
The important thing here is to understand based on the adjustments you’ve made, how this affects the light as ascertained from reviewing the histogram graph.
The follow up to this step is that when you download the photos, I always look at three things before you begin editing.
1. The Histogram
2. The EXIF data that is downloaded and contains all of the Camera settings
3. The photo, and try and ascertain what it is you might want to change based on # 1& 2 above.
Try it!
Larry
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| February 14th, 2007 11:34 AM | |
ssomajik
Joined: Sep 18, 2006
Posts: 161 | Part 2
What do "spikes" instead of curves indicate? I sometimes get the histogram centered but It's spikes. I have been using it since you first explained it to me but I never seem to get curves. There isn't one on the camera but I have taken more shots after checking pic in the computer....Beth |
| February 15th, 2007 08:14 PM | |
LVE
Joined: Aug 1, 2006
Posts: 825 | To Beth & Cheri
This takes some time to play with and understand. The spikes tend to demonstrate that the lighting is not balanced. If you look at the histogram and compare to the photo, you can see this. For example, if the sky is very bright in a section of the photo, the histogram will spike in the same are as the photo where it is bright. A flat histogram demonstrates that basically the whole photo is flat, and usually this is a dof issue, or contrast and balance issue or shadows and highlights or midtone balance. I am telling you that if you continue to shoot in Auto mode you are going to see this a lot more than if you play with settings and make adjustments. It doen't mean it is a bad photo, just not a very good one! |
| February 17th, 2007 02:41 PM | |
LVE
Joined: Aug 1, 2006
Posts: 825 | yes, Kind Of
Remember, every photo does not have to have a Bell Shaped curve to be good. On my camera when I look at the histogram after the shot in the LCD, the photo is on top, and the histogram under it!This lines up and you can see the areas in the curve and what is happening in the photo in that area above it You can do the same thing in your software, ACD, Place the histogram under the photo. |
| February 28th, 2007 08:03 AM | |
SJD
Joined: Sep 18, 2006
Posts: 73 | Auto Modes - Manual Modes
Is is possible to have an outline of the settings to look for when shooting in manual mode? I have been shooting lately with my camera on Program and shooting in Raw. I am manually setting the focus, changing the exposure and lighting. Is there a sequence in which all this is done? For example setting the F Stops and DOF. Thanks so much, Skeeter |
| February 28th, 2007 08:06 AM | |
SJD
Joined: Sep 18, 2006
Posts: 73 | P.S.
Larry, thank you for this information it is very valuable and I am ready to get off Auto Modes and start using my Manual Modes. |
| February 28th, 2007 08:54 AM | |
andreyG
Joined: Sep 19, 2006
Posts: 390 | good luck
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| February 28th, 2007 08:55 AM | |
andreyG
Joined: Sep 19, 2006
Posts: 390 | oops, wrong page.
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| February 28th, 2007 11:26 AM | |
LVE
Joined: Aug 1, 2006
Posts: 825 | Skeeter
This really has to come from experimenting. Think of this as a general rule of thumb.
DOF depends on what kind of DOF you are trying to get. In a landscape type shot, you typically want more DOF meaning you want the entire shot to be in focus and be able to see the detail. You want less light = High Aperture; for a longer period of time = Slower SS.
When you are trying to blur out a background, this means you do not want the entire shot to be in focus, like shooting a flower, then you want less DOF. In this case you want more light = Lower Aperture and faster shutter speed.
I find the easiest way to do this with stationary objects, is to use Aperture Priority. Please understand that there are other factors like ISO and EVA adjustments that ave a bearing on every shot!
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| February 28th, 2007 09:10 PM | |
LVE
Joined: Aug 1, 2006
Posts: 825 | Goes Both ways
Let me know if I can help ! |
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