Tip 2 – The Histogram, Exposure and Exposing to the Right
 

When I first started taking photographs, years ago in the good old days of film, the camera I owned was a Zenth and it had an exposure meter just above the lens mount so one of the hardest things to work out was the correct exposure for each lens you had attached. The way I got around it was to write down the settings and light conditions, expose the film and then wait up to two weeks for the photos to be returned from the lab before I knew the correct settings. I kept all these settings in a little book and took it everywhere I went with my camera so I could set the camera correctly for the type of image I wanted. It was still hit and miss because I had to adapt it for each lens I had. At the time I only had two, a 50mm and a small telephoto but it was still a real pain. It was worse with slide film as there was less latitude to play with and I had to throw so many of my photos away. My next camera was a Praktica as the lens mount was the same but the exposure was taken Through The Lens (TTL). I had a lot more keepers with this camera.

One of the biggest innovations brought along with the digital revolution in photography was the histogram. The histogram shows you all the colour tones within your image from black all the way to white. If most of the lines / information are to the left of the histogram then the image is either made up of dark tones or is underexposed. If most of the lines / information are to the right of the histogram then the image is made up of light tones or is overexposed. Using this information shown within this tool, means that you should get a correctly exposed image. A lot of people just rely on their exposure meters to get the exposure right but you shouldn’t. Yes I know that the exposure meters in today’s cameras are a lot better, especially the evaluative or matrix metering mode as these metering modes meter the whole area and compare it with information stored in its memory to get the correct exposure, but they can still get it wrong at times. A camera is just a machine and it does not know what you are trying to photograph. If you don’t believe me then look up and, without making changes to your camera’s exposure, try photographing a Cormorant flying with a cloudy sky behind it. All you will get is a black bird with a grey sky and a lot of detail in the bird will be missing. Therefore after I have taken a photo I always check the image on the rear LCD and the histogram before carrying on, as long as time permits. This is to see if there are any highlight warning flashes on the image and check that the exposure is correct on the histogram. Do not just rely on the picture on the LCD. This is a JPG of your photo and even though some parts might be flashing don’t panic, when you download it into your RAW software you might still be able to rescue it. If it shows a thin line on the bottom right of the histogram then you should be OK, but if it shows a build up on the right then data might be being lost but still check it with your RAW software before you discard the image. So how much exposure compensation is needed? When you examine the histogram on the back of your camera you will see feint lines running vertically. On a Canon camera there are four of them so the space between each of these lines is roughly a stop of light. So when I examine the histogram I am able to tell how much adjustment is needed quite quickly to get the exposure I want. So I check the histogram and if it needs adjustment then I move the exposure compensation wheel to add or reduce the exposure. When I am checking the histogram I will adjust it so that the histogram will be close to, but not over the right hand edge. I shoot using a technique known as Exposing to the right. Doing this gives me as much quality out of the image as possible. When you do this the cameras LCD images might look overexposed but check the histogram as that’s what gives you the true information. Once adjusted then I will carry on taking photos but I will still check the histogram every now and then because as you know light changes.

Sorry its geek time. When wildlife is concerned you have got to have a Chris Packham moment and I for one love them. I’ve stated above that I expose to the right because I want to get as much quality out of my photos as possible. My camera, like most DSLR’s made in recent years, is 14 bit and has 3 colour channels. Each of the Red, Green and Blue channels have up to 16,384 tones of colour. These tones are divided like so, the brightest stop has 8,192 tones, the second 4,096, the third 2,048, the fourth 1,024, the fifth 512 and the darkest stop has 256. This shows there is more information / tones in the brightest stops than in the darkest ones. This is the way a digital sensor works. More information / tones of colour equals better quality and more detail but also, a bit more computer work. You will have to do a bit more post processing by using the Exposure, Brightness and Contrast controls in your RAW software but you will get a better quality image at the end of it.

Get used to using the histogram as it’s one of the best tools to help you with your photography.