Take your portrait photography to the next level by moving up to Manual mode

Canon mirrorless cameras make it easy to shoot in Manual (M) mode. There's no need to use an external light meter or rely on trial and error with repeated test shots. You can see the exposure in real time through the electronic viewfinder and adjust your settings before taking the photo. It's quick, intuitive and makes Manual mode more accessible than ever. But why bother setting your exposure manually in the first place?

Manual provides consistency from shot to shot. If the lighting isn't changing, the exposure stays the same. This frees you to concentrate on your subject, composition and framing while you're shooting, and can help to reduce the amount of time you spend editing your photos.

You control all three elements of exposure when you shoot in Manual mode: aperture, shutter speed and ISO – although you can set the ISO to Auto and let the camera adjust the sensitivity for you. Being able to determine every aspect of the exposure is why fashion and portrait photographer Samuel Sarfati uses Manual all the time – even during dynamic portrait shoots.

"I want to be sure that I am in full control of my image," he says. "I can see the effect of changing the settings directly in my viewfinder, which is amazing. It means that on a shoot I can be very focused on my images and be in control of every aspect."

Samuel has used manual exposures ever since his father introduced him to photography using a vintage film camera. If you're used to shooting with your camera set to fully automatic, however, then moving to Manual might seem a stretch too far at first – especially for portrait photography, where there are so many other things to think about. So here is a step-by-step guide to moving up to Manual, starting with understanding automatic modes such as Scene Intelligent Auto mode, taking more control with semi-automatic modes such as Aperture Priority, and then mastering all three elements of the exposure triangle when you’re ready to experiment with manual exposures.

As a first step, understand what automatic modes are doing for you when you select any of these using the Mode dial on the top of the camera. Scene Intelligent Auto mode is all about speed and making things easy. It takes care of exposure, leaving you to concentrate on the person you're photographing and the look you want to achieve. The camera will detect that a person is in the frame and automatically optimise the settings for a portrait. Fully automatic modes offer limited creative control, though. You won't be able to select an aperture setting to precisely control the depth of field, for example – although you can use the Creative Assist function to adjust the background blur.

The Portrait Special Scene mode optimises the settings for portraits, such as blurring the background with a large aperture and softening skin tones and hair. As with Scene Intelligent Auto, you can't set a specific aperture, shutter speed or ISO, so it is more limiting than the more advanced shooting modes. However, you are able to choose RAW image quality, which allows you to fine-tune the overall exposure when you process your images in Canon's Digital Photo Professional editing software.

Creative Zone modes give you more creative control, allowing you to manually set one or more of the exposure elements for a specific effect. Aperture Priority is ideal for portrait photography, as this mode lets you adjust the aperture to alter the depth of field and make your subject stand out. The camera will automatically adjust the shutter speed (and ISO if you have set this to Auto ISO) to give you a standard exposure. If you are using Auto ISO, you can specify the minimum shutter speed on most Canon cameras to prevent the camera selecting a slower shutter speed, helping to avoid blur caused by camera shake or subject movement.

Semi-automatic modes don't give you the consistency of Manual, though. If the background for your portrait changes to a brighter or darker one, then the camera may give you a different overall exposure – and you should use exposure compensation to correct it.

When you're starting out with Manual, you might be unsure which aspect to set first: aperture, shutter speed or ISO. In addition to their role in determining an exposure, these three settings impact the image in different ways.

Set aperture first if control over the depth of field – how much of the scene is in sharp focus – is the priority, as it is likely to be when shooting a portrait. Large apertures (small f-numbers) reduce the depth of field, small apertures (large f-numbers) increase it. Setting a large aperture makes it easier to separate your subject from the background.

Shutter speed determines how movement is recorded in your image – whether that's subject movement or any movement of the camera when you're shooting handheld. If you're shooting action, then shutter speed is the setting to set first. Faster shutter speeds help you achieve sharper shots, so once you've selected your aperture for a portrait, set a shutter speed that will allow you to shoot sharp handheld shots. A rule of thumb is to start with a shutter speed equivalent to the inverse of the focal length you’re using – so 1/100sec with a focal length of 100mm. Image stabilisation can help you get sharper shots at slower shutter speeds, but this stabilises only your movement – not your model's. If the model moves during the exposure, the image may still be blurred. To determine a safe shutter speed, take test shots at different shutter speeds and review the results.

Think of ISO as a control that lets you use your desired combination of aperture and shutter speed in the lighting conditions. It's the first setting that Samuel adjusts when the light changes. "I try to keep ISO between 100 and 1,600," he says, "although I will go higher if I have to because of the quality of the RAW file and being able to add noise reduction when I process it."

You can raise or lower the ISO according to the light available. Alternatively, set ISO to Auto and let the camera adjust it as the light changes. You're able to retain control over how bright or dark the overall exposure is using exposure compensation when using Auto ISO.

After setting your preferred exposure using the aperture, shutter speed and ISO, you may decide to change one of the settings. Perhaps you want to use a larger aperture for a shallower depth of field, or a faster shutter speed to freeze a moving subject.

If you just alter one setting, however, you will also make the image brighter or darker. Think of the three exposure elements as working together: if you open the aperture by one stop to let more light in, for example, then you need to compensate by reducing either the shutter speed or the ISO by one stop to maintain the same exposure.

Making these decisions at speed – such as during a relatively fast-paced portrait shoot – can be daunting at first, but there are ways to manage them confidently. Pairing a Canon RF lens that has a Control Ring and an EOS R System camera with two dials allows you to assign aperture, shutter speed and ISO to separate controls.

"I use the Control Ring for ISO, with the aperture and shutter speed on the body," explains Samuel. "It means I can change everything very quickly." Because he shoots every day, changing the settings is second nature. "I don't think about it anymore," he says. "It's a bit like playing videogames. When you're playing a game, you don't think about your buttons, you're just doing it. If you know your camera, you can control everything in your image."

Even though you set the exposure yourself in Manual mode, the camera's light meter remains active. As you change the aperture, shutter speed and ISO, the exposure level mark moves left and right along the scale at the bottom of the viewfinder and rear display. If the mark is in the centre, then the metered area will be recorded as a mid-tone. If it moves towards the left of the scale, the metered area will be recorded darker. If it moves towards the right, it will be recorded brighter.

By adjusting your exposure settings so that the position of the exposure level mark matches the tone of the subject you're photographing, you'll have a great starting point.

The key thing to remember is that the camera's meter is only a guide. It can tell you how an exposure will place a tone within your image, but it doesn't know the mood you're trying to create.

You don't have to rely on the exposure level indicator in the viewfinder – or even the brightness of the display itself. Enable the live histogram, and you'll be able to see precisely how the image will be exposed before you take a shot.

This makes it easy to move beyond just producing a standard exposure and start making creative decisions about how to use brighter or darker exposures to enhance the look of a portrait.

Samuel has the histogram displayed continuously. "I always make sure I'm exposing it in the area I need to be and the mood that I want," he says. "After that, I know that the RAW file can capture everything I want. So, it's very easy to make sure the image is well exposed."

Not every image has to be made with a standard exposure. For example, if you want to create a low-key portrait, where the image is dominated by dark tones, or a high-key portrait dominated by bright tones, then you may want to alter your exposure so that the histogram is closer to the left side (for low key) or right (for high key).

It's worth paying particular attention to the histogram when you're shooting portraits you plan to print. Images can appear brighter on screen than they do on paper, so retaining important highlight and shadow detail will give you greater flexibility when preparing images for print. Shoot in RAW so that you can further fine-tune your exposures.

As your confidence grows, Manual mode becomes less about choosing aperture, shutter speed and ISO settings, and more about understanding the creative effect they have on your final image. For portrait photographers such as Samuel, that's the real benefit: the consistency and creative control to maintain their vision from shot to shot.