English Language Teaching in Japan and Asia

Usually, after you have taken a picture, you can view it. In your camera's menu you can view the histogram and see how the exposure turned out. Also, in PhotoShop, you can review histograms for all your pictures. The 'perfectly exposed' image is one where the histogram makes a near perfect bell curve, similar to the one below.

However, I've found that in reality, it can be ok if the 'bell shape' is skewed rather narrow and at one end. What you need to know is, especially since it's easy to 'blow out the highlights' with digital, is if there's too much light information being gathered by the photocells on the sensor. If there's too much, then that'll be represented by the appearance of a flat top (see figure below). That means that there's more light information available, and so all the details of like textures and shadows can be lost, resulting in highlights.

If you do have images with flat tops, then you'd say that these images have blown-out highlights; that is, the bright areas are too bright, so they lack colour information, and you see only white, and no texture as well. This is not ideal. The other thing is you cannot retrieve this information in PhotoShop. The Photocells were overloaded, and so the opportunity is gone.

What you would do in this situation is either increase the shutter speed, close the aperture a bit, add a Neutral Density filter, or reduce the iso to something closer to 100 or 80 (or whatever the lowest you can set your camera to).

Usually, when you push the green arrow button on your camera, immediately after taking a photo, you should be able to push something else so you can view both the image and its histogram. Look it up in your camera's owner's manual.

 Over exposed. Here, too much light has affected the picture. This could have been reduced by using a polariser or Neutral Density filter. The over exposure occurs when the sensor has received more light than its capacity, and so we get these blow outs, where no significant amount of digital information can recover the detail.

 Sky Problems. This is a problem when too much light hits the sensor and the sensor is quickly saturated. It also happens on film, but much less so. Use either a lens hood or a polariser to prevent this, when the sun is strong, intense, on the side and slightly in front of the camera.