Photography: SLR camera



Following up on the previous photography related post, here is a brief review of how an SLR camera works. This is not necessary information to take pictures but it certainly helps if you want to manipulate the camera in doing what you want it to.
There are currently two most popular types of cameras available:
-the point and shoot cameras for those who prefer simple and automatic.
-the DSLRs (simply SLR in the film days) which are more popular with the photography nuts and the professionals.

I use both but obviously prefer the DSLR for its flexibility. Though today the higher end point and shoot cameras are as sophisticated as the entry-level DSLRs and provide almost all of the functionality.

So what is a DSLR camera. Directly translated, its a digital single lens reflex camera. Meaning, we see a single reflection of the image coming from the lens. Since there is no distortion of the image by multiple reflections, what we see (compose) is very close to what we get.

Simplifying it further, a digital camera is nothing but a box, with :
1. A sensor in digital cameras (film in the older versions). The sensor collects the image and processes it.
2. A shutter in front of the sensor which moves away when we click a picture. Imagine a square sensor and then a tiny gate in front of it which moves up and down.
3. A mirror angled in front of the lens and viewfinder such that the light entering the lens gets reflected on the mirror into the viewfinder. The sole purpose of the mirror is to provide a preview of the picture. When we click a photo, the mirror moves out of the way.
4. Lastly the lens which has an aperture on one end (towards the camera) whose diameter can be adjusted.

The two important controls in the construction, that the user has, which govern the properties of a photo are:
1. the speed with which the shutter moves out of the way and comes back in front of the sensor.
2. the diameter of the aperture of the lens.

So following the path of light in the figure above, light enters through the lens, through the aperture, reflects onto the mirror and can be seen in the viewfinder. Its out of scope to go into lens theory here. So just imagine an object in front of the lens, which the user can see reflected in the mirror.

Once, we click, meaning the shutter is released, the mirror moves up away from the lens, the shutter moves up and light enters from the lens onto the sensor creating an image. Voila!


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