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Aperture settings on your camera

Author: Ben Reeves
He is a travel writer and photojournalist working in Phuket. Originally from the UK, he arrived in Thailand by way of Oman.
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Camera Aperture Settings – Getting off Full Auto

I’m always disappointed to see people with 100,000 baht’s worth of camera equipment using the Full Auto camera aperture settings. Basically, that person has created the world’s largest, most expensive point-and-shoot. It is such a waste!

That doesn’t mean you have to jump straight in to Manual mode, though, which can be overwhelming because it essentially becomes a balancing act of settings, each of which has a knock-on effect which alters the nature of the image. Most cameras have a number of semi-auto modes which allow you to control these settings individually.

camera aperture settings

Today, we’re going to talk about Aperture Priority because it is the root to creating probably the best known and most popular photographic effect, variously known as the ‘depth-of-field’, ‘depth-of-focus’ or ‘making the background all blurry’ effect. It creates excellent artistic photos because it makes the subject of your image really stand out. There are couple of ways to produce it:

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Camera Aperture Settings – What is Aperture?

The word ‘aperture’ is a posh word for ‘hole’. Basically, it is the size of the opening which the lens creates in order to focus light onto the sensor when you open the shutter. It is one of the three camera aperture settings which have a major impact on the amount of light hitting the sensor and creating the image – the other two being the ISO and shutter speed, which will be covered in a later post.

How exactly this hole functions is, if I’m brutally honest, a complete mystery to me. It is something to do with the refraction of light as it passes through the lens. It controls what is mostly known as the ‘depth of field’ – that is, how much of the image is in focus. Knowing the science behind why it works is entirely irrelevant. Knowing how to apply it is all that matters.

camera aperture settings

Camera Aperture Settings – Big-small-big, small-big-small

The famous blurry background effect is created because the depth of field is small. If your camera is in Aperture Priority mode, scrolling the controls one way whatever you focus on will be perfectly sharp, but everything behind it will seemingly be out of focus. Conversely, if you scroll the other way, everything from the end of the lens to infinity will be pin-sharp, which is generally the preferable option for landscapes, obviously.

This effect has something to do with how much of the light is hitting the sensor at the right angle or something but, as I said, I really don’t understand the science behind it and that ignorance has never diminished my abilities. All I remember is a little mantra: “big-small-big, small-big-small”.

This actually started out life even simpler. The easiest way to remember this trick is that a bigger number equates to a greater depth of field. Taking a picture of a person with a fuzzy background means you want a smaller depth of field, so you want the setting to be a small number – f/2.8, if you bought a good lens and lower if you bought a great one.

camera aperture settings

If you’re taking a picture of a subject in front of a nice vista and want the background to still be sharp, you want a greater depth of field so you want a higher number. You don’t generally need to go all the way to f/22 or more – f/8 is often enough.

Before you ask, the aperture is always expressed as a value of ‘f’ and I have absolutely no idea what the ‘f’ stands for. I think it’s a mathematical symbol.

The added word in the middle of my mantra came about because I was reading photography magazines which confused me by saying that you should have a “big aperture” to achieve the shallow depth of field effect. I then realised that they didn’t mean a big number; they were talking about the size of the hole, which defies all logic and actually gets bigger as the number gets smaller.

So, the full expressions is “big number = small hole = big depth of field, small number = big hole = small depth of field”.

Camera Aperture Settings – The Zoom Method

I learnt an alternative way to create this effect during my lessons in TV news production at university. The video cameras we were using were on the basic side and playing around with aperture with video requires all sorts of filters which the university didn’t have, so they showed us a cheat.

Basically, if the newsreader was stood close to the camera, the background would be in focus. However, if they stood far away from the camera, with the shot zoomed in so they were not just a speck on the viewfinder, the background blurred. Again, I neither know nor care about the science behind this.

Naturally, this meant using a really long microphone cable (or radio microphones, which never worked), so we didn’t use it that often. In the case of photography, it means using a long telephoto lens, which is more expensive. I only mentioned this method for the sake of completeness. The aperture method is far simpler and more commonly employed.

Middle Ground

The most common mistake new photographers make when they discover this trick is to only ever use the extremes. I’ve got to admit, I’m just as guilty of this as anyone else, but I slowly learnt to employ the camera aperture settings in between f/2.8 and f/22, gradually discovering the approximate depth of field each value creates until I can just about estimate the required setting to achieve the desired effect. That comes with practise.

A particularly good example of where the middle ground is important is with group photos during events. You want to have a crowd of people all in focus with their background fuzzy because it looks cool, but the people are all stood at different distances from the lens. If the depth of field is too shallow, the person you focus on (which should be the one nearest to you) will be fine, but the person stood right next to them might be slightly blurred and the person photobombing behind them will be totally out of focus.

See The Light

As I said before, aperture is one of the methods of controlling the light hitting the sensor. With your camera in Aperture Priority, you will notice that manipulating the aperture, causes the shutter speed to automatically alter to compensate.

As the size of the aperture increases (and the number decreases, because reasons), more light is hitting the sensor. The shutter speed will have to increase, exposing the sensor for less time, so that it is still getting just the right amount of light for a perfect picture.

camera aperture settings

The practical upshot of this is that the extremes of aperture might not always be available to you. If you try to increase the depth of field in the evening, with limited ambient light, you might find the shutter speed plummets too far to be practical. Similarly, if you try to reduce the depth of field on a bright day in glaring light, you might find your camera unable to increase the shutter speed far enough and the picture will be too bright.

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