I wrote this a couple of years ago. The principles are still the same but my writing was a bit stilted back then. No matter. Short concise sentences will help you understand Basic Photography.
Photography is light:
1. Light hits something, film or a sensor
2. The film or sensor reacts to how much light hits it
3. The film or sensor saves the image.
An automatic DSLR camera makes adjustments for you. It reads how much light is hitting the object you want to shoot and adjusts three things to ensure you take a good picture.
An automatic camera adjusts :
1. The size of the opening the light goes through. (Aperture)
2. How long the opening is actually open. (Shutter speed)
3. How sensitive the sensor is to the light that hits it. (ISO setting)
You can manually adjust all of these three settings yourself. This will change the other two settings. If you think of all of this as an equation, A + B + C = D, it might make more sense. D is a constant, it’s a fixed number which represents a perfect picture.
A is aperture, B is Shutter Speed and C is the ISO setting. Since D must always be the same, you can see that if you change any of the variables, A, B or C, then you have to adjust one of the other two variables.
If you open your aperture (the hole) more, you have to leave it open for less time, right? If you make the sensor more sensitive to light, you have to either make the hole the light comes through smaller or shorten the time you let the light into the camera. Any change that is made in one, affects the other two. If you remember these variables, you’ll begin to understand what makes a good picture as well as understanding the terms ‘underexposure’ (too little light, too little time open or low sensitivity or a combination of all three) and ‘overexposure’ (too much light, etc.)
Next time I will explain why you might want to adjust one of the three variables.
Thanks for reading. If you like this post, tell others about it. OK? Follow me on Twitter: @_BrianMahoney