Understanding light - Part I

"Photo" in photography originates from Greek word, phos, phot which means Light. Sometimes we are so involved in understanding technical aspects of camera, lenses and what not, we totally ignore spending some time to understand the basics. Let's spend few minutes to understand how we can exponentially improve our clicks by just giving importance to this 5 letter word - "LIGHT"

Let's start from the basics and understand what role light plays. If we take a cross section of our camera, we can easily see that amount of light that hits the image sensor decides how much our pictures will be exposed. A picture clicked with a very good subject, outstanding location or ultra high resolution may end up in the trash folder of your computer, if it's not properly exposed. 

We can always do post processing to increase the exposure of picture but the results that we will get will not be as good as exposing the camera sensors with appropriate light in the first place. Sometimes it's very obvious to tell whether picture is properly exposed or not, but best way to tell, is by looking at the histogram of your picture. 

A histogram of an image has 3 main sections. On extreme left we have shadows or dark portions of our image. If our picture is under exposed, it will be skewed towards left. Similarly if it's over-exposed it will be skewed towards right. A properly exposed image has most part of the histogram appearing between left and right extremes. 

Here is an example of how histogram changes as we click images at different f-stops with rest of other parameters constant. 0 - shows properly exposed photo. +1 and +2 means the image was over-exposed by 1 and 2 f-stops respectively. In the same way, -1 and -2 in the diagram shows that the image was under-exposed by 1 and 2 f-stops respectively.

Let's take some stuff in color. Below is a picture of a beautiful pigeon, which I got a chance to shoot during a safari. I didn't realize ISO was left high after last night shoot. The result is in front of us. If we look at the pic, we might have noticed, it's overexposed. If we check histogram of the pic, we can see that most part of it is on right extreme, hence overexposed. White part of the image is washed out , losing all the details,  so is the focus point of the subject. 

While you may want to intentionally underexpose or overexpose some subjects, but it's not recommended to do that unless you know what you are doing. You can look at the corrected original image here.

Overexposed Pigeon

Now that we have understood, the impact of light in our images, let's try to figure out, how can we fix this and get "correct exposure". Before we proceed, let me say it in bold - "There is no correct exposure for any image". 

Its all about finding the correct balance which will make the subject in the image stand out. Light falling on the subject and the light entering through the shutter of your camera decide the final exposure of your image. Fortunately we can control both. 

Overexposed Pigeon Histogram

Light falling on the source can be controlled using a lighting set up like a studio ( strobe lights, flashes etc) for indoor conditions. For outdoor conditions we can use a reflector or camera flash. I will cover this aspect of light more when I am covering Portrait Photography, but for now let's talk about the light which enters through the shutter of your camera. This can be controlled using appropriate combination of aperture opening and shutter speed. Photography is all about finding the right balance between these two aspects of light.

Apart from intensity of light, we miss to consider the aspect called - "Angle of incidence". A source of light which is falling on subject from right side can produce different result than source of light illuminating the subject from left side. Shadows are the result of "Angle" aspect of light. Below are set of few images which illustrate how changing the angle of light source is resulting in different images. 

"Number of light sources" plays a very important role in deciding the exposure especially under indoor conditions. When we are shooting with single source of light, chances of getting shadows are high. Two sources of light can minimize that. More the light better it is, but after certain point, adding more light source becomes redundant. 

Will come up with the 2nd part of this blog soon, for now wrapping it up. Next part, we will see how we can master setting up appropriate lighting conditions and much more...

Comment below, let me know what do you think?