So when I am walking around taking photos in either London or on my travels I always like to have a little nosy at the settings the tourists are using on their cameras! It amazes me how many people have these really nice DSLR or Mirrorless cameras and yet they are using them in Auto mode! Don’t get me wrong I did the same when, as a fresh faced 23 year old, I brought my first camera and I too had no clue how to use it! So in this series of posts, I will hopefully try and demystify a few of the main settings of your camera to ultimately get you out of shooting in Auto mode!
DISCLAIMER – This series of posts is aimed at people shooting with either DSLR/Mirrorless cameras or any camera that allows you to manually adjust your settings. If you are unsure if your camera has manual modes please referred to your cameras operating manual! Also as you may have already gathered this will definitely not be a scientific explanation of the principle techniques of photography. If you would like to know all the sciencey stuff then there are loads of great articles which go into these topics in a much more thorough and scientific way. My goal is to give you an understanding of how the settings on your camera work so that you can get out there taking great pictures right away without having to learn boring terms such as “chromatic aberration”
If you don’t care about how your camera works and would like to skip right to the bit about using aperture priority mode and how that works then skip down and read from “F Stop and Depth of Field”
Now before I get into today’s topic – Aperture & Aperture Priority – we need to cover a small amount about the basics of photography – WAIT DONT GO!! COME BACK!!! Are you still there?? It’s ok I didn’t like them anyways.
So your camera has 3 basic elements which allow you to control the exposure (how bright or dark) of the image.
These are

- Aperture
- Shutter Speed
- ISO (How sensitive the camera sensor is to light)
These 3 elements combined are used to achieve the desired exposure and each element will affect the image in a different way. By understanding how these elements affect the image you’ll be able to make creative decisions about how you want the image to look (or that’s the idea anyway). These 3 elements are known in the photography world as “The Exposure Triangle” – not as sunny as the Bermuda Triangle but equally as easy to get lost in! It’s a triangle because adjusting one of these settings will affect one or both of the other two elements! So for example, if you adjust your shutter speed to allow more or less light in you will need to compensate, the increase or decrease in light, by adjusting either your Aperture or ISO! See – clear as mud! Trust me when we actually starting using these settings it will all make sense and definitely isn’t anywhere near as confusing as I am making it out to be!
Aperture – The camera’s Iris
So in this article, we are gonna be talking a lot about the camera’s aperture. The aperture is like the iris in your eye, it opens and closes in pretty much the same way and it allows more or less light in (respectively). But the aperture controls a lot more than just the amount of light entering the camera. It also controls the Depth of Field (DoF). Now there are loads of websites which will give you a much more scientific explanation of Depth of Field but basically, it is the distance in between the closest point and the further point of an image that’s in focus or in other terms it’s how “Deep” the focus is… got it? “BUT WHAT DOES THAT MEAN TIAN??” Ok I’ll show you.

In this image of a flower you can see that only the very front of the petal is in focus and going away from the camera the focus falls off very quickly. This is a very shallow depth of field. Only a thin slice of the flower is in focus. Why is this useful? Well, your eye is naturally drawn to the area that is in focus.

Now if you take a look at this image the whole flower is in focus. In fact, even the background is more distinguishable. You can even see a stem from another plant in the background. This is a wider (or deeper) depth of field.
So why is learning to control your depth of field going to make your images better? Using a shallow depth of field will allow you to separate the subject from the background or a wider DoF creates depth in the image (which is good for shooting landscapes). It can let you control the feeling of space. In the image above, the shot with very shallow depth of field, the image feels more intimate, you feel much closer to the subject whereas the shot with a wider depth of field has a feeling of more space or being further away from the subject. You will tend to see photographers who shoot intimate portraits using very wide apertures whereas landscape and cityscape photographers will favour much smaller apertures. Obviously, with this being said there are no hard and fast rules to photography so experiment with different apertures to see which ones you prefer for each situation.
For F’ Sake!
So when you brought your sparkly new camera, the salesmen or even website will most probably have mentioned the lens that you were getting with the camera. Now the lens will have a focal length such as 35mm or 50mm (don’t stress about focal lengths right now) as well as some f-numbers for example f2.8 or f3.5-f5.6 etc. These f-numbers are known as “F Stops”. Now there is a whole bunch of scientific stuff about “stops of light” and “full stops”, “half stops” etc that I won’t get in to in this beginners guide but for know just think of them as different sizes of aperture!
Right, time to grab your camera (if you haven’t already)
Now I want you to be super brave… I’m right here so there is nothing to be afraid of… I want you to change the mode dial from “Auto” to “A” (Nikon/Sony) or “Av” (Canon/Pentax).. done? Right, that’s it.. all done! I said I’d get you out of Auto and now I have… So I’ll see you guys later! BYE!
You knew I wasn’t serious (when am I ever serious!!)
You are now in Aperture Priority mode! Now I will get to what this actually means in a sec but first I want you to find where your camera is displaying its current f stop or f(number). If you have a camera like mine you might have a display on the top…
or if you don’t have a display on the top it might display it on the rear screen..
or you can usually see it when you look through the viewfinder! If you really can’t find it then you might have to look at the camera manual. Now I want you to use the Scrolly Wheel (yes Scrolly Wheel is the technical term!) on the camera and by scrolling it to the left and to the right you should see that the f stop should be going up and down. Higher end cameras might have 2 Scrolly Wheels in which case you might have tried both to see which one actually changes the f stop. By using the Scrolly Wheel to change the f stop you are changing the size of the opening of the aperture! You may notice that the numbers aren’t sequential and probably seem nonsensical but there is actually a good reason for this but for now, just know that the smaller the number the larger the aperture… ok?
So for example, if your aperture is at f4 and you scroll a few clicks to the right to f5.6 you will be reducing the size of the aperture. Still with me? In this example, f4 is a larger aperture (opening in the cameras iris) than f5.6. Now I want you to scroll allllllllll the way to the left so the f stops get lower. Eventually, the f stop will stop going down… this might be at f1.8 or f2.8 or even f3.5 depending on the lens… but this low number is the widest aperture of your lens and probably the number that was mentioned on the website ad or mentioned by the salesmen (35mm f1.8). If you hang out with enough photographers (and why wouldn’t you – we are all fricking cool) you will undoubtedly hear them talk about f1.4 or f1.2 etc… they are talking about the widest aperture of the lens they use. See photographers are well cool! Wide apertures are awesome for the reason I’ll talk about later! Now that you know what the widest f stop of your lens is I want you to now scroll alllllllllll the way to the right and once again the number will eventually stop going up. Usually, this is around the f16-f22 range. This will be the smallest aperture or smallest opening of the cameras iris!
*PRO TIP – READ ONLY IF YOU CARE ABOUT TECHNICAL STUFF*
If you want to know what the f stop numbers mean and the reason that the lower the f-stop, the wider the aperture is because the f-stop is the ratio between the focal length and the diameter of the aperture. So, for example, a 100mm lens at f4 would have an approximate aperture diameter of 25mm.
100mm (focal length) / 4 (f4) = 25mm – Simples!!
This is why the smaller the f stop – the wider the aperture.
For example:
100mm at f2.8 (100/2.8) = 35.7mm aperture (wide)
100mm at f16 (100/16) = 6.25mm aperture (narrow)
F Stops and Depth of Field
We are now starting to pull it all together – if you’ve skipped down the article straight to this part then frankly you’ve missed out on some really amazing jokes by me also some interesting information about how cameras work.. but mainly my flawless sense of humour :P.
So how does F stop and Depth of Field relate to each other… The lower the f stop (therefore the wider the aperture), the shallower the depth of field. Got it?
Low F stop e.g f1.8 = wide aperture = shallow Depth of Field
High F stop e.g f22 = narrow aperture = wide Depth of Field
So why chose a wide aperture (shallow DoF) over a narrow aperture (wide DoF)?
Well as shallow Depth of Field will isolate the subject from the background. Like in the flower example earlier, our eyes are naturally drawn to the area of the image that is in focus. If you have ever seen a wildlife photo where the animal/bird etc is in focus but the background is a nice smooth blur… that will have been shot at a wider aperture. Portrait and Wedding Photographers often like to use wide apertures to really isolate the main subject (say the bride or groom) so that the eye is drawn to them. Macro photography is a great example of wide apertures and a shallow depth of field (google “macro photography” and you’ll see what I mean”) as it really gives a sense of intimacy. I tend to shoot all of my portraits in the widest aperture my lens has to, once again, give my subject that separation from the background like this image..
Why should I choose a Narrow aperture (wide DoF) over a wide aperture (shallow DoF)?
As I mentioned before, a wide DoF gives a feeling of space and depth to the image. Landscape and Cityscape photographers tend to use higher apertures so that everything from the immediate foreground to the further visible point (infinity) is as in focus as possible. Take for instance this image..
As you can see everything from the closest point to me (the very bottom of the image) to the furthest part away from me is in focus. This image was shot at around f16 and it gives you depth, space, and perspective.
So remember if you want to isolate the subject of the photographer, whether that’s a person, animal, car, object or whatever.. a Low f stop/wide aperture/shallow depth of field with separate them from the background. If you want to create depth, a feeling of space and add perspective to an image then a High f stop/narrow aperture/wide depth of field will achieve that!
As an example, I have shot the same subject (in this case a flower) with varying apertures for you to see how the change in aperture changes the feel of the image..
Boom! Right home stretch!!
Aperture Priority and how it works
Ok so now you are an Aperture Jedi master and totally ready to shallow DoF the crap out of all your images! But the thought of shooting in full manual (where you have to set Aperture, Shutter Speed and ISO yourself!) seems like a real ball ache! This is where the wonders of Aperture Priority comes in. In Auto mode the camera will take a look at the scene you are about to shoot and it will decide what aperture and what shutter speed to use based on the amount of light available (usually ISO is set by you however most cameras do have an Auto ISO function but we’ll come to use that in another post). It will also try to flatten the image with the inbuilt flash and that always makes an image look terrible. The problem with this is that the camera will always try to find a middle ground for both aperture and shutter speed. It will try to keep the shutter speed relatively high to reduce camera shake (more about that when I talk about shutter speed) but it will also try to use a middle range aperture.. say f5.6-f8. This means that you’ll end up with a real middle of the road depth of field.. which ends up making a real middle of the road image (I’m trying not to use the term “boring” but that’s basically what I’m saying) and you know what if that’s your thing – cool, but for me I want something a bit more interesting! Aperture Priority, however, is kind of a “semi-manual” mode. What this means is that you set the aperture you want to create the desired depth of field and then the camera will decide what shutter speed it needs to expose the image properly. So if you want to shoot a portrait in f1.8 (wide aperture = shallow depth of field) the camera will then adjust the shutter speed for you for a correct exposure! Now you only have to worry about the aperture! That’s why I called is a “Semi-manual” mode.. you are manually controlling the aperture.. but the camera is automatically setting the shutter speed for you!! BOOM! It comes in really handy in a plethora (check out the great word use) of situations. I use aperture priority a lot when shooting weddings because in a fast-paced environment where you are moving around a lot, the light is changing all the time and you often don’t have time to think about your shutter speed in that fraction of a second when you see something happening and getting the shot before it’s over. I’ll also have my camera in aperture priority when shooting street photography as, once again, you’re moving around, the light is changing all the time, one minute you’re in sun… next you’re in shade and you might suddenly see some the perfect shot and don’t have time to check the light meter and adjust the Shutter!
Now before I release you into the big wide word armed with aperture priority there are some drawbacks to using this mode that need to be talked about first. The camera will adjust the shutter speed to whatever it thinks it needs to get the correct exposure and in low light that will mean that it may need to slow down the shutter speed significantly (maybe even to a shutter speed of 2 or 3 seconds – which in the camera world is practically a lifetime). If the shutter speed gets too low and the camera is not in a fixed position (like on a table or a tripod) you will start to introduce “camera shake” into the image – basically, the image will start to become blurry! Not because it’s out of focus but the camera is moving whilst the shutter is open which creates motion blur. Don’t worry I’ll explain this better next time. This means that in low light environments (at night/evening, in a dark room, etc) you will need to keep an eye on what the shutter speed is and if you start to see motion blur in your image, your shutter speed may be too low. If this is happening how do you bring the shutter speed back up? You increase the ISO (sensitivity of the camera’s sensor) – see I told you ISO, Aperture and Shutter Speed all affect each other. Take a look at these examples..
In this image, you can see that there is a lot of camera shake. The image doesn’t really look out of focus just like everything is vibrating badly! This is because to get the correct exposure the camera picked a shutter speed of 1/2 second! In photography 1/2 second is a really slow shutter speed and is long enough for the camera to move slightly whilst the shutter is open. So to fix this issue…
I raised the ISO up to 6400!! The shutter speed is now reading 1/125 which is fast enough to handhold the camera and get the shot. If you’re desperate to have it on the lowest ISO then you could stabilize the camera on a bag or tripod and then use the 1/2 second shutter speed. I’ll talk about why low ISOs are good when I look at ISOs in an upcoming post.
Right, I think that covers it! This post will probably be slightly longer than the others but only because we need to cover a few extra bits but it’s important to know how these things work. So head off and start snapping pics with aperture priority. You can set your apertures based on the scenarios I have spoken about or you can do your own thing. As I said this is a tool for you to use to create images you like. There is no “one size fits all” approach to these techniques so if you want to shoot portraits with a deep depth of field cool! or if you want to shoot landscapes with a shallow DoF that’s cool too. As they say “Rules are meant to be broken”.. unless it’s the speed limit at which point you get a £60 fine!!
So I hope this post has been interesting for you and I hope it helps you to get out there, take more shots and create better images!
If you have any questions about Aperture and using Aperture Priority then feel free to drop me a line at tian@tianwilliams.com
Feel free to head over to my social media accounts and give me a follow and a like and I will see you next time when I’ll show you other ways to get out of Auto.
Thanks
Tian x
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