02 - A photograph captured with Camera

A photograph is derived from the Greek words ‘Phos’ meaning light and ‘Graphe’ meaning drawing. How cool … Light drawing . So how is a light drawing done?  How can light draw?… Its not physical color.
The concept was developed more than a century ago of exposing a light sensitive surface to light through a lens to draw an image. The process matured over time to create an equipment for light drawing by name camera which used light sensitive film rolls to capture photographs. Several types of cameras started getting built to cater to different purposes and thus making it more and more accessible and commercialized. The most popular version is 35mm format cameras – meaning cameras that uses 35mm width films to capture photos.
The last decade focused on building and enhancing digital capture medium for light drawings instead of films and thus got named as digital cameras. In simple words, In digital cameras the concept remains same, just that a roll is replaced with a electronic sensor. There are a lot of options and variations that can set on the digital sensors and thus extends the possibilities of creativity in taking a photograph but we will talk about them later.

Ok…. time to cut the crap and talk about a Camera. Following is a camera built in 10 mins with powerpoint :)

A SCHEMATIC DIAGRAM OF A CAMERA

Explaining in simple language the definitions of some key terms are as below (These definitions will change slightly once we start learning more and I will explain the significance of the values for these terns later)

APERTURE
For a photograph to be captured a hole need to allow light to flow in and reach the sensor. The amount of opening corresponds to aperture. A lens attached to a camera has some properties that tells what is the maximum and minimum opening that lens allows to flow in. ( we will revisit aperture later)


In the above picture see how using blades the size of the hole can be changed to allow the amount of light flowing in.
Summary: Aperture is the opening through which light flows in through to reach the film / sensor. The photographer can control the size of the aperture and in some cameras, the camera controls the aperture

Shutter Speed
There is a screen that protects the film from getting exposed to light before the photograph is taken (Remember the famous click). When the trigger/button is pressed to take the photo, the shutter opens for a certain duration to allow light (flowing through aperture hole) to reach the sensor and then closes again protecting the film / sensor from getting any further light
A shutter looks like the following with the sensor sitting behind it in a dark place.



It opens for some time duration based on the values set by the user allowing sensor / film to get light to create a photograph. The time for which the shutter remains open while taking a photograph is called the shutter speed of that photograph. Some times it is 1/2500 seconds. Wow!


Summary
The key elements of taking a photograph are

• Shutter Speed
• Aperture
• Sensor (We will talk about sensor parameters later in a separate post for itself)

I have setup the ground to talk about the “Bucket of light” and in my next post it will make the physics behind photographs clear.