Exposure 101

Lines, originally uploaded by du3z.

The first thing I ever did read on photography, even before I bought my first DSLR, was about exposure, and rightly so. After all, photo-graphy is the "drawing" or the "art" of light.

I'm sure most of us have handled some form of digital camera before...even PnS (Point-and-Shoot), and have come across the term "ISO". High ISO shots look dotted (noisy) and Low ISO shots look clean - that much we figured.

Let me introduce the Exposure Triangle. Namely, ISO, Aperture, and Shutter speed. One of the best analogies I've read was from Digital-Photography-School. Picture this:

A window on a deserted building. Sun rays are piercing through the window and you're standing in the room looking out.

The size of the window is the aperture - the bigger the aperture or the size of the window, the more light shines through - right?

Suppose the window shutters were the shutter blades in the camera. If the window shutter was closed, no light shines through (assuming it is opaque). If i open the shutter, light shines through...and then I close it. The faster I close it, the less light gets to shine through. Conversely, the slower I close it, the more light shines through.

Of course, slower shutter speed and "longer" shutter exposure is interchangeable in terminology to me at least.

The photo had a shutter speed of 22 seconds. This is normally not achievable in bright day light as 22 seconds will allow too much light, overexposing your photos into pure white. But in the night, this is possible and the effect of the car trails is shown for such a slow shutter. If you like that, try it!

Lastly, the ISO setting is the sensitivity of your eye, or camera, in essence. Low ISO = less sensitive. High ISO = more sensitive. It's just like a sunglass over your eye. If it's too dark, take it off (increase the ISO). If it's too bright, decrease the ISO!

Now all these 3 play a part in determining what exposure you get. So with this knowledge, I went out to shoot. Then bags the question...when to use what?

I believe each of these deserves a mention of their own...so till then, stay tuned!