Image #1

                                             Image #2

                                              Image #3

                                                “Capturing Alaska”

                                                 with Wayde Carroll






                                                      Histograms


 Because more people are now shooting digitally rather than with film, and because I shoot with digital SLR’s, I thought I’d bring up the ever present, largely ignored histogram.
 Most people tend to take an image, make sure it appears ok on their LCD and then move on to the next image. It’s great to be able to see that you’re exposure is close with just a glance at the back of your camera but what you see on the LCD monitor isn’t always an accurate way to judge your exposure.
 The brightness of your LCD may be off from what you actually see on your computer monitor. Some perfectly exposed images appear too bright or too dark on the cameras’ monitor. Also, the surrounding ambient light can effect how you see the LCD image. If you are shooting outside on a bright, sunny, day it can be very hard to see the image on your screen and therefore it appears too dark. If you are shooting at night or in deep shadow the image can appear brighter than normal in comparison to your surroundings. To add to the mix, the brightness of your LCD image can vary with a slight tilt of your camera. You need to be looking at it straight on.
 Some of you may ask “Why does any of this matter when you can just fix it in Photoshop?”
 Well, while it is true that you can easily make corrections in Photoshop and other photo editing software programs, there are reasons why achieving an optimal exposure is still desirable.
 If my exposures are spot on to begin with, it will save me valuable time in the post-processing phase of my workflow. Digital files usually need some slight tweaking, weather it’s a bit of sharpening, contrast adjustment, or color saturation etc., so why add an extra step to the process?
 Also, if my image is overexposed or underexposed there is often times unwanted contrast and color degradation after the exposure is brought in line. These problems can often be dealt with as well but at a much higher cost time-wise.
 This brings me, finally, to our subject: histograms.
 Most digital cameras today come with a feature that will display a histogram on their image-viewing screen. If it does not come up automatically, check out your manual and you should be able to call it up. A histogram is a graph which shows you the tonal range captured in your image. 

 What’s important to remember is that the shape of your histogram doesn’t matter, it’s the placement on the graph that we are concerned with.
As you look at the histogram the dark tones are represented on the far left, the mid-tones in the middle, and the highlights are shown on the far right. What you want to do is check your histogram after an exposure and make sure the tonal range matches the scene before you. If you are shooting at night (see image #1) your histogram will be show most of the data on the left side. If there are some highlights etc you will still see them represented as a smaller amount of data on the far right side. If you are shooting a very bright or high key image  (see image #2) your data will be heavy on the right side of your graph. Therefore any mid-tone image (see image #3) will have a nice distribution all the way across your histogram.
 You still need to be careful within these guidelines as well. If you are shooting the night scene and your histogram is showing all the data going off the left side of your graph you need to be wary. All of your data should be contained within the graph if you expect to hold detail. With the night exposure you should be able to see where the data on the left just ends before going off the screen and some will be in the mid-range and highlight area. If you have no data on the right you are underexposed and will lose detail in the shadows. The converse is true for the high key image. If you have no data on the left then you are overexposed and will lose detail in your highlights. Most cameras have little flashing dots that appear when you have areas that may be losing detail. Use them as an additional tool to help notice discrepancies with your exposures.
 With proper exposures you will save time, headache, and produce higher quality prints. Good luck!