Zen and the Art of Photography part 1: The Photography Triangle

If you can remember this one simple concept you will learn how to use manual settings on your Camera and get perfect exposures every time:  Photography is a Triangle.  Now, I studied photography for years and it seems like I took a lot of technical classes, but it is really not very complicated at all.  The base of all photography is the exposure triangle of Aperture (f-stop), Shutter Speed and ISO (“film” Speed).  The Photography Triangle is a simple mathematical formula:  Exposure= f-stop + shutter + Film speed.

Q:  What is Aperture/ F-stop?

A:  Aperture, more commonly referred to as F-stop or F-number is the adjustable opening in the lens that controls how much light is let in.  F-stop controls the amount of light hitting the “film” plane and it controls Depth of field.

Q What is Depth of Field?

A: Depth of Field is how far into an image you have sharp focus.

High depth of field: At f/32, the background competes for the viewer’s attention.

Low depth of Field: At f/5.6, the flowers are isolated from the background.

Q: What is Shutter speed?

A: The shutter is a tiny curtain that blocks light from hitting the film plane/sensor when you are not taking a shot.  The Shutter moves out of the way when you push the shutter button (the button that takes the picture) at a shutter speed– measured in fractions of a second.  A shutter speed of 60=1/60th of a second.  Shutter speed controls the sharpness of objects in motion.  It is recommended to never hand hold a camera and shoot with a shutter speed less than 60.

Q: What is film speed/ISO?

A: Film speed, usually written as ISO or ASA is the sensitivity to light of a film or digital sensor.  The lower the number the less sensitive, the higher the number the more sensitive, BUT  the lower the number the sharper the rendering and the higher the number the more likely you are to get grain/noise/distortion.

400 Speed film

Q:  What is Correct exposure?

A: Exposure is when light passes through the f-stop opening and is allowed to hit the film/sensor by the shutter opening up.  Correct exposure is the exposure you want that is neither too dark or too light (under and over exposed).

The above sentence is the kicker.  Here’s the deal, your camera is an idiot.  You will never take great photos depending on your automatic settings alone.  Photography is a decision making Art.   You should ask your self two basic questions:  Do I want more or less depth of field? And do I want to capture objects in motion sharply or with some blur?  How to answer these questions depends on you, the subject and available light.  And you will have to choose one over the other.  I will address the decision making aspect in future posts.  For now, let’s concentrate on learning The Photography Triangle.

In The Photography Triangle:

1 F-Stop= 1 Shutter speed

1 F-Stop=1 Film speed

1Shutter speed= 1 film speed

1Shutter speed= 1 F-Stop

etc…

for example:

If you are using 100 speed film (set your sensor to 100)  and your exposure meter shows correct exposure at f/8 x 1/250ths of a second

And say, you want to reduce your depth of field so you “open-up” your f-stop 1 stop to f/5.6 you must also speed up your shutter by a factor of 1-stop to 1/500ths of a second to maintain correct exposure.

Why?  Because as you open up the f-stop to let more light in, you must reduce the time that light is hitting the film/sensor

Same example, but now you are underexposed by 1 stop

You decide to keep your settings at f/8 x 1/250ths of a second because you are getting what you need, So you need to increase ISO by a factor of 1-stop to get correct exposure.  What do you do?  Change the film speed(ISO) setting to 200.

Using this formula, if you have ISO 100 with exposure set to f/8 x 1/250ths of a second and you are over exposed 1 stop, what change to your shutter speed will bring you to correct exposure?

Well, being overexposed means there is too much light, so we have to reduce the light, and since we decided to keep our film speed and f-stop the same we will……….increase the shutter speed 1 stop to  1/500ths of a second!

Confused?  Complicated?

Just remember this:  Photography is a triangle!  Whenever you adjust one of the three parts of exposure you must change one other aspect to maintain correct exposure.