How to control shutter speed when using Aperture Priority mode
Everybody has their preferred shooting mode when it comes to taking pictures.
When shooting sports or wildlife often the advice is to switch to shutter priority mode to have control over your shutter speed, favouring a high shutter speed to freeze the action and leaving the camera to select the aperture.
This is fine, but what if you want to use a high shutter speed and use a wide aperture at the same time? You could,
- Switch to manual mode, select your aperture and preferred shutter speed and leave your ISO on auto. However, you then have no control over the ISO being used.
- Use the aperture priority mode, select the widest aperture for your lens and let your camera select the shutter speed and ISO, but then you have no control over the shutter speed being used or ISO.
Neither of these options are the best, what you really want to do is, control the aperture, shutter speed and ISO at the same time.
Now, you may be thinking that controlling all three elements of the exposure triangle requires you to shoot in manual mode, but for sports, wildlife and action photography we need to be able to react quickly and not fiddle with too many settings as we may miss a photo opportunity.
So what is the solution? Use your camera in aperture priority mode and make use of manual ISO to control your shutter speed.
How does it work
You set your aperture and ISO manually leaving the camera to select the shutter speed. The ISO becomes the way to control your shutter speed and noise.
This works as we are making use of the correlation between ISO, Aperture and Shutter speed (exposure triangle), optimising our exposure and controlling all three elements of the exposure to our advantage.
- Control over aperture use – we can set the widest aperture providing us with more light through the lens.
- A variable shutter speed – as we are using a semi auto mode, our shutter speed will vary according to changes in the brightness levels of the scene and to the iso setting, maintaining an optimal exposure.
- Control over ISO and shutter speed – We can adjust our ISO up or down to select the fastest shutter speed we desire to freeze our subject whilst maintaining control over the ISO. This way, we use the lowest practical ISO setting needed to achieve our desired shutter speed and have some control over noise.
By setting our camera to aperture priority mode and then adjusting ISO to reach a suitable shutter speed we are controlling 2 elements of the exposure triangle with one setting (ISO).
This works really well if you have a dedicated ISO button on your camera, you can just press the iso button and then dial in the ISO number that you need to arrive a the shutter speed that you want or need to use.
It may take a moment for the penny to drop, but when it does, you will have a lightbulb moment and realise that this is a very easy way to use your camera and have full control over exposure, control noise and be creative with your use of aperture and shutter speed. And it allows you to work fast.
Most experienced photographers can look at a scene and pre-select their aperture, ISO and shutter speed to get roughly the right exposure before shooting, they can then meter the scene and tweak their exposure if needed. Which is what I do, I think about my subject and the brightness of the scene and I
- Preselect my aperture
- Set my preferred working shutter speed by adjusting my ISO setting.
- Leave my white balance on auto.
This way, if I need to shoot quickly or unexpectedly, I have a good chance of capturing the shot as I am shooting in semi auto mode (aperture priority), if I am slightly off with my pre-selected settings, my shutter speed will adjust automatically to give me a correct exposure. I can then dial in more or less ISO to re-adjust my shutter speed or make use of my exposure compensation button to adjust exposure as necessary.
If you have not tried working this way, then you should, it basically cancels out the need to use other shooting modes, except in certain circumstances where you may want to leave your camera in full auto mode (holiday photos as an example) or when the conditions you are shooting under merit shooting in full manual mode (studio work for example).