Where do I start with aperture?
Aperture is the F number to the right of the screen. Called an F-Stop.
Aperture is, in my opinion, the most important thing to get your head around when you start photography. I'm not saying this because it plays a bigger role than shutter speed or ISO, but more because when you're shopping for your first lens it's one of the biggest factors that will determine which lens you purchase.
Before we get into lenses, lets talk about how aperture effects the photos you take.
BOKEH! Bokeh is that nice creamy look that every photographer strives for. You wanna get that beautiful blurred background while keeping your subject in focus. If you go into my portraits you'll see that I do this a lot, and, personally, I love the look. So, how do you achieve this look? APERTURE. A lower aperture number will get you a blurrier background, but at what cost? Lets say you're photographing a couple. Your aperture is at its widest and you start to notice that no matter how much you hold still or how much you focus, one person is always out of focus. This is because the wider the aperture the smaller or narrower the depth of field is. That means that if you're focusing on one person and the other is even slighter further back they will be out of focus. Lets see some examples to better understand.
The photo above perfectly illustrates how aperture works. The photographer focuses on the boys face and the girl is completely blurred at f/2.8, but the larger the number gets (or the smaller the opening gets) the sharper the girl gets. Pretty much everything around the area that was focused on was completely blurred at f/2.8. Which means it is a very narrow depth of field. Lets look at a better example of depth of field.
The further the subject is, the easier it is to get them in focus at a wider aperture. If you were to get a close up portrait of their face and were to focus on the tip of their nose, chances are that the eyes will be out of focus at a wider aperture.
Why should you know all this when shopping for your first lens? Because you're going to want a FAST lens. What does this mean? A fast lens means it has the ability to reach a wider aperture, which means you can have a fast shutter speed because the wider aperture lets in more light. This is very important to a professional photographer because they tend to work a lot in low light places like wedding venues or indoor sports events. Obviously, when working in low light it's important to have a wider aperture so that you can raise your shutter speed and get sharp images. Light is the name of the game, and if you cant capture light efficiently then your job as a photographer is going to be a hard time. Usually the best lenses can achieve a constant wide aperture at any zoom. Here are a couple of lenses. I'll explain why the price difference is so huge.
Here are two Nikon Lenses. Both are zoom lenses, but as you can see there's a $1600 difference. The reason this is is because the top lens has a constant aperture of 2.8 while the bottom one starts at f/4 at 50mm and goes all the way up to f/5.6 at 200mm. (For now we will disregard the rest of the info on the name. We will save all that for a future blog about lenses.) Both lenses can reach higher apertures, but the point is that one can stay at f/2.8 no matter what zoom it is at. Another reason the bottom lense is so cheap is because you CANNOT use it on a full frame camera because it is a DX (Crop sensor) lens, and as I said in an earlier blog, full frame sensors are a go-to for professional photographers because of the low light capabilities. For these reasons, this lens is a very slow lens that will probably not do very well in low light situations unless you use a very low shutter speed and a tripod. Even then, your subjects are not going to freeze in time so that you can capture their photo without motion blur. That is why wider apertures are very important when searching for your first lens. This is something that you will better understand out in the field. Practice at different apertures and try to understand how it works.