Today I shall try and explain what is happening behind these words and hopefully give you a better understanding of how exposure is created and get you on your way to understanding the manual settings a little bit better.
The exposure is created from three things: shutter speed, aperture and ISO. This is sometimes called the exposure triangle.
Shutter speed is simply the the amount of time that the shutter is open and letting light onto the camera's sensor or film. The longer the shutter is open the more light is let in, shorter amount of time, less light.
|Shutter speed of 1/4 Seconds|
|Shutter speed of 1 second. Too long. The image is shaky.|
Being able to have long shutter speeds allows you to experiment with things such as light painting.
I found this the hardest concept to grasp, but now that I think I have got my mind around it, I am keen to share my new found knowledge!
|f/5.6. Small depth of field.|
Aperture is measured in f-stops. You can go up or down a stop to halve or double the size of the opening and therefore the amount of light. The confusing part is that the bigger the number, the smaller the aperture and the smaller the number, the bigger the aperture. For example, an aperture of f/5.6 has a bigger opening than one of f/22. To help me remember this I picture the size of the closed blades; the more amount they are covering the larger the number.
F-stops don't go in integer increments but instead look something like: 2.8, 4, 5.6, 8, 11, 16... This baffled me but I've recently found an interesting article that explains why they are that way. F-stops are calculated by dividing the focal length by the aperture diameter (If you would like to read the article you can find it here. It's very interesting and shows the maths behind it). As for the pattern between the sequence of numbers, you simply multiply a number by two to get the number two places along or multiply each number by the square root of 2 to get to the next number.
F-stops also indicate your depth of field (how much of your picture is in focus). The trick to remembering this is easier: big number, big depth of field, small number, small depth of field.
Now to see how these effect the exposure together. For the aperture if you go up one stop you halve the amount of light and if you go down one stop you double it. The same for shutter speed. Now let's say for example that you are happy with your exposure but want to change your depth of field. You can get the same exposure by changing the shutter speed and aperture in relation to one another (however much you change one, you must change the other in the opposite way). In this way you can get a range of different combinations for the same exposure.
|ISO of 800. You can see the image is grainy|
I hope that you found this interesting and have learnt something new. :)
Hi, I'm Shendl, a South African that has a dislike of seafood, an affinity for interesting words and a yearning for adventures.