Understanding Aperture: it's all in the math

What is with all the F4, F8, F16 and so on? That deals with the lenses aperture. Each lens has a maximum and minimum aperture. Whether if be a slower F5.6 lens or a fast F1.4 lens what does this all mean. In order to understand photography, you MUST understand your equipment and math. The F1.4 really stands for F/1.4 or F divded by 1.4. So in this case, we'll say you have a 50mm lens that's a F1.4. So the F in this equation is the focal length of your lens, in this case 50mm divded(/) by 1.4.. (F/1.4) which is the typical writing listed on a lens or when you post about the speed of your lens. So, back to the example; F 50mm is our lenses length, divided by 1.4, gives us an aperture size of 35.71428571428571 mm in size. that's a huge opening to allow light in.

Another example; My lens that I use for my landscape photography is a 40mm lens. it is listed as an F4 maximum aperture, F22 minimum aperture. So at F4, my aperture that lets the light in to my sensor of my Canon EOS 5D Mark2 is, 10mm.

So an F1.4 is considered as a fast lens because it is able to take pictures quickly because it's opening is alot larger than my 40mm lenses at maximum exposure. So it is easy to see why understanding the size of the maximum aperture of your lens is important in your photography on an everyday basis.

an analogy I like to use is; A large pipe can send through more water than your garden hose to water plants or fill up a pond. but you lose DOF, (Depth of Field) at larger apertures and increase your DOF at smaller apertures.

Hope this helps you!
-Christopher