The camera histogram is one of the most important indicators of how well exposed your photograph is. The graph that is displayed represents on the left shadows, in the middle mid-tones and on the right highlights.
Thank you to digital camera world for the graph.
For a well-exposed image, you are looking for a rise from the left bottom corner to a peak in the middle and then dropping down again to the corner on the right. However, remember this is a perfect world.
The camera histogram graph may have peaks and troughs. Meaning that it might start at the bottom in the left-hand corner Rise to a peak the drop slightly rise to another peal and then drop to the left-hand corner.
Either of these scenarios will indicate a well-exposed image.
When looking at the camera histogram what you don’t want to see is the peak starting high on the left-hand side then a gentle curve upwards in the mid tones and then finishing high on the right-hand side. You may also see starting high on the left dropping, rising and dropping in the mid tones then rising high on the right. This indicates a badly exposed image which may be over or underexposed.
If a portion of the histogram is touching either edge this is called clipping. It means that there is a loss of detail in the image. On the left side, the clipping occurs in the shadows and will be completely black (no detail). On the right side in the highlights will be completely white (no detail).
If a certain portion of the histogram is “touching” either edge, it will indicate loss of detail, also called clipping. Highlight clipping (areas that are completely white and absent detail) occurs if the graph is touching the right side of the histogram. Shadow clipping (areas that are completely black and absent detail) occurs if the graph is touching the left side of the histogram.
HOW CAN YOU CORRECT THE GRAPH ON THE CAMERA HISTOGRAM
The best way to do this is to use a light meter. This way you can set the ISO, aperture and shutter speed to the readings taken. This will give you a well-exposed image. I use the Sekonic L478DR
The other way is adjusting the shutter speed on the camera. This adjusts the exposure. By dialling in a faster speed you will darken the image. If you want to make it lighter then use a slower speed.
You must remember that ensuring you have the correct white balance is also key to this process. See here for further information on white balance here.
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