# Apatures and Photography

Now let’s look at where the numbers that represent aperture (f4, f5.6 and so on) come from and why they get larger as the diameter of the aperture gets smaller. Feel free to skip this page if it seems a little complicated. You don’t need to know where the numbers come from, just what they mean. But for those of you who are interested, here’s why: The number that represents aperture is the ratio between the focal length of the lens and the diameter of the aperture: aperture = focal length : aperture diameter For example, if the focal length of the lens is 50mm, and the diameter of the aperture is 25mm, the aperture is f2 (this is sometimes represented f/2): aperture = 50 : 25 = 2 Here’s another example. If the focal length of the lens is 50mm, and the diameter of the aperture is 6.25mm, then the aperture is f8: aperture = 50 : 6.25 = 8 You can see that the number representing aperture value becomes higher as the size of the aperture becomes smaller. The reason this style of measurement is used is that it is transferable between lenses. Learn more at http://markalexander.over-blog.com/2016/12/nantucket-portrait-photographer-for-beautiful-photos.html and http://mpommett79.hatenablog.com/entry/2016/12/25/063905 You may have noticed that some camera lenses are bigger than others. That also means the physical size of the aperture created by the iris blades changes too. The clever bit is this: any lens will transmit the same amount of light at an aperture setting of say, f8, regardless of the physical size of the lens and the physical diameter of the aperture created by the iris blades. Each of these lenses varies greatly in size and weight. Yet each lens, if set to the same aperture, will let exactly the same amount of light pass through to the camera’s sensor. Shutter speed The concept of shutter speed, unlike aperture, is quite easy to understand just from looking at the numbers. The slower the shutter speed, the longer the shutter opens when you take a photo and the more light reaches the sensor. shutter speeds get faster 1/8000, 1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2 shutter speeds get slower The figures above show shutter speeds in fractions of a second. It’s quite easy to see how it works. Each shutter speed in the sequence is twice as long as the one preceding it. For example: 1/4000 second is twice as long as 1/8000 second (1/8000 x 2 = 1/4000) 1/2 second is twice as long as 1/4 second (1/4 x 2 = 1/2) To keep things simple, a couple of the figures are approximations: 1/60 second is approximately twice as long as 1/125 second 1/8 second is approximately twice as long as 1/15 second. Every time you double the shutter speed, double the amount of light passes through the camera’s shutter when you take a photo. Do you notice a pattern emerging? When we looked at aperture earlier, we saw that each main aperture setting let either half the amount or twice as much light as the next in the sequence. It’s the same with shutter speed. Each of the main settings lets through either half the amount or twice as much light as the next in the sequence. Aperture and shutter speed are the two controls that regulate the amount of light that reaches the camera’s sensor when you take a photo. They work together. Aperture controls how much light passes through the lens. The shutter speed determines how much of that light reaches the sensor. If you’ve been playing with the shutter speed settings on your camera you may have noticed that they go all the way up to 30 seconds. Here is the sequence of shutter speeds, this time in full seconds, that continues on from the previous one: 1, 2, 4, 8, 15, 30 The shutter speed range of most digital cameras is from around 1/8000 second to 30 seconds. Learn more at http://spanishinperu.org/nantucket-wedding-photographer-2015/