How To Make Sense Of Your Histogram

Understanding the exposure controls on your Pentax camera, such as the K-3 II can help you to produce more balanced and well exposed pictures. Here, we'll run down some features of Pentax cameras that can be utilised to help you achieve a better exposure:

Histogram: The histogram is a graph that represents the range of tones in your image. The left hand side of the graph shows the darker tones, and the right side of the graph the lighter ones. When you take an image, if most of the peaks on the graph are to the left, then the image is most likely under exposed slightly. If most of the peaks are on the right, then the image will be over exposed. 

You can make the histogram visible on the live view screen by pressing the info button on the back of your Pentax DSLR. You can also view the histogram of the image you've already taken by pressing the same button while viewing your images. 

A good exposure generally features a peak in the graph towards the middle of both the dark and light tones section. It's handy as it's able to tell you if the image is under or over exposed even if your eye tells you it looks ok. 

'Blinkies': When you take an image, if parts of over or under exposed, the camera will show you by flashing a colour over the affected area. This means there is either too much, or too less light in these areas, and so the camera is unable to record any detail in that area.

On Pentax DSLR models, the camera flashes up under exposed parts as yellow, and over exposed parts as red. You can then adjust your exposure accordingly, adjusting shutter speed and aperture, until the image comes out more evenly exposed.   

There will be times when adjusting the exposure will push the 'blinkies' the other way - for example photographing sunrise or sunset. Focus on the sky, and the foreground will be under exposed, get the exposure right for the foreground, and the sky will be over exposed.

There are two main ways to combat this:

• Use an ND graduated filter to darken the sky slightly and enable you to get some detail in the ground and the sky. Graduated filters fade from filter at one end to no filter at the other, meaning the sky will be darkened but the ground will stay the same, allowing for a more equal exposure to be taken.
• You could take an image with the sky properly exposed but the ground dark, and the ground properly exposed but the sky too light, and stack them in post processing software to create an image where both parts are equally exposed. This will require use of a tripod to ensure the camera doesn't move at all during taking both images.