I realised that I’ve written about shooting modes, and I’ve written about exposure. But never wrote about how and when you might use aperture priority or shutter priority modes on your digital camera.
Treat this topic as if you’ve moved from full-auto or program mode, into aperture priority mode. I’ll walk you through everything you need to know.
Full-auto mode allows you to change only the image format and the burst fire mode. It will even use the pop-up flash if it thinks it needs to.
Program mode is similar to a priority mode. You can change the likes of metering, white balance, and so on. But you can’t change the shutter speed or aperture (you can change the ISO).
OK, now we’ve seen the difference, lets have a look at what it can do.
When you switch to aperture priority mode, it does exactly what it says on the tin. The exposure gives priority over the aperture setting, and then shutter speed adjusts according to that.
The shutter speed can drop below a manageable number when using a maximum aperture. This results in motion blur, so just keep an eye on your camera settings.
Let’s say you set the aperture to f/8, and the shutter speed is 1/200 of a second. Then you decide to widen the aperture to f/5.6 (which allows twice the amount of light in).
The camera will change the shutter speed to 1/400 of a second to counteract for the extra light. This automatic change in camera settings ensures a correct exposure.
This almost automatic mode leaves space and brain capacity for other things, such as creative control. It also works across all digital camera platforms, especially DSLR cameras such as Canon and Nikon.
How Do Priority Modes Work
When it comes to shooting modes, most of the questions are what is aperture priority mode? or what is shutter priority mode. they differ somewhat from the manual way of things.
I use aperture priority mode about a third of the time. I use shutter priority mode and manual for the other two thirds.
It’s good for several reasons, the three main ones being sharpness, depth of field and light.
When you widen the aperture to a lower number, say f/2, you allow much more light into the lens. This, in turn, allows you to speed up the shutter speed.
Wider apertures also mean there’s a shallower depth of field and vice versa.
When you narrow the aperture to around f/8-11, this is when the lens will be at the sharpest.
As you can see, there would be plenty of situations where you might want to use aperture priority over shutter priority or even manual.
Only Shoot in Manual Mode?
For all the people that tell you, you should only shoot in manual mode – you’re wrong. At least that’s my opinion. There’s plenty of cases where you might want to choose manual – about a third of the time for me.
Let’s have a look at some of the situations where you would want to use the aperture priority mode.
First though, it’s worth mentioning an advantage that aperture priority mode has over shutter priority mode. This is when it comes to exposure.
A longer exposure will always allow more light into the lens. But this won’t be at speeds which will allow you to hold the camera in your hand.
When it comes to aperture, it’s to do with the hardware of the lens. So if you buy one with a wider aperture, you can keep the shutter speed at handheld speeds.
This is while allowing a wide aperture to allow more light in. It’s a good way to improve the performance of your camera.
When You Should Use Aperture Priority Mode
Situation 1 – Good light / Sunny day
When the light is constant, you could use manual mode. But chances are that you’re creating extra work for yourself. Why make the small changes that the camera is going to make for you?
If you want to change the exposure, you can do so with exposure compensation meter provided in the camera.
When the light is good, you don’t need to worry about blurring your images. The shutter speed is always going to be fast enough to capture the movement.
This is particularly true if the light is good.
There’s an old rule ‘sunny 16‘, which suggests a narrow aperture for shooting in the sun, and it works. This is another reason to shoot in aperture priority mode.
In good light, you’re rich with light. You might as well use a lot of it by narrowing your aperture to produce sharper images.
Situation 2 – Portraits
When shooting portraits, the lighting is usually pretty good. Whether you’re using flashes or natural light.
We tend not to make things harder for ourselves than they need to be. Comfortable lighting situations mean that we can take the photos at the aperture of our choosing.
I like to shoot at a range of apertures when taking portraits, but f/8 is one of my favourites. I find that my photos come out the sharpest at this aperture, which works great for portraits.
Situation 3 – Landscapes
Landscapes have a foreground and a background, and often a middle ground too. To see everything in focus, you need a wider aperture, somewhere up to about f/16 works for me.
There are times where I will use a tripod, and if I am then use manual mode. But more often than not, I’m using my camera handheld.
Here, aperture priority mode works fine as I’m not playing with any longer shutter speeds. This is where the depth of field becomes important.
Situation 4 – Shallow Depth of Field
Shallow depth of field is achieved by opening up your camera’s aperture. This allows more light in at the same time. It’s not a small amount more light either, it’s a lot more light.
The jump from f/2.8 to f/1.4 allows four times more light in. The shutter speed can counteract this, in aperture priority mode.
When you change the DoF, chances are you will be experimenting quite a bit. You’re giving yourself more work if you’re using manual mode. It’s not all about manual mode.
When You Shouldn’t Use Aperture Priority (But Think You Should)
Situation 1 – Poor light / Darkened room
I’ve said this before. The beauty of a wider aperture is that it allows your camera to see more light. This is especially true in a darkened room.
But that doesn’t mean you should select aperture priority mode. I find it best to use shutter speed priority. Let me explain…
When you’re in low light, the two main worries are about exposure and camera shake. You’re either not getting enough light or getting blurry pictures. Or both.
If you set the camera to aperture priority then you’re only dealing with half of the problem. That’s light.
When you’re in shutter speed priority, you can account for the camera shake (say, 1/30 or 1/50 of a second). The aperture will adjust around the speed to produce the exposure.
Even if there’s not enough light, the aperture will go to its widest. You can play with the photo in post-production.
At least that way you don’t have a blurred photo, which you can’t fix (yet).
Night photography is a different game. And it’s reserved for the likes of manual, rather than aperture priority mode.
The lighting becomes so unpredictable, you have to make calculations and estimations in your head. It’s really more a case of trial and error.
A note from Josh, ExpertPhotography's Photographer-In-Chief:
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