Aperture Priority vs Shutter Priority: Which to Use

These two modes are the practical middle ground between full auto and manual mode. You control the one setting that defines the look, and the camera handles the rest of the exposure triangle.

What each mode locks and leaves

Mode	You set	Camera sets	You control
Aperture priority (A / Av)	Aperture	Shutter speed	Depth of field
Shutter priority (S / Tv)	Shutter speed	Aperture	Motion

In both modes you can leave ISO on auto or set it yourself. The camera adjusts whatever you did not lock to keep the meter balanced.

Aperture priority: control what is in focus

Set the f-number and the camera finds a shutter speed to match. This is the mode most photographers live in, because depth of field is usually the creative decision that matters most.

• Portraits: open up to f/1.8 · f/2.8 for a blurred background. See aperture and f-stop explained.
• Landscapes: stop down to f/8 · f/11 to keep the whole scene sharp.

The catch: in dim light the camera may pick a shutter speed too slow to hand-hold, like 1/15, and you get blur from your own movement. Watch the shutter readout and raise ISO if it drops too low.

Shutter priority: control motion

Set the shutter speed and the camera finds an aperture to match. Use it when motion is the point.

• Freeze action: 1/1000 · 1/2000 for sports, birds, or kids.
• Blur motion on purpose: 1/8 · 1/4 for flowing water, or slower for light trails. See shutter speed explained.

The catch: the camera can only open the aperture so far. In bright light at a slow shutter speed it may run out of room and overexpose, and in dim light at a fast shutter speed it may run out and underexpose. The aperture readout will blink when this happens.

What the blinking numbers mean

Both modes warn you when the camera runs out of room, and the warning tells you which way to fix it. Canon's EOS R50 manual for aperture priority says a blinking 30" shutter speed means underexposure, so open the aperture or raise ISO, while a blinking 1/4000 means overexposure, so stop down or lower ISO. Its page for shutter priority works the same way in reverse: if the lowest aperture value blinks, the shot is underexposed, so use a slower shutter or a higher ISO; if the highest blinks, it is overexposed, so use a faster shutter or a lower ISO. Other brands use the same idea with different labels.

Fix aperture priority's weak spot with Auto ISO limits

The main risk in aperture priority is a shutter speed that quietly drops too low indoors. Auto ISO with a minimum shutter speed closes that gap. Canon's EOS R3 manual describes a minimum shutter speed setting for ISO Auto that works in Program and aperture priority, defaults to the reciprocal of the focal length in its standard Auto setting, and can be shifted faster for moving subjects. The same page notes the camera will still go slower if it reaches the maximum Auto ISO, so set that ceiling deliberately. With both limits set, aperture priority becomes close to foolproof: you choose depth of field, the camera protects the shutter, and ISO absorbs the rest.

Three worked examples

Portrait in open shade, aperture priority. Set f/2 for a soft background. The camera picks 1/800 at ISO 100. That is fast enough for anything a person does, so shoot. If you move indoors and it drops to 1/30, raise ISO or set an Auto ISO minimum of 1/125.

Bird taking off, shutter priority with Auto ISO. Set 1/2000 to freeze wings. The camera opens to the lens's widest aperture, say f/5.6, and Auto ISO climbs to 1600 to fill the gap. Noise is the price of a sharp wingbeat, and it is worth paying.

Waterfall at midday, shutter priority. Set 1/4 for silky water. The aperture value blinks at f/22 because there is too much light, even at base ISO. No aperture can fix that; you need a neutral density filter. The ND filter calculator turns your metered shutter speed into the exposure time with the filter on, and how to photograph waterfalls covers the rest.

The screen does not always show your depth of field

Most cameras keep the lens wide open until the moment of capture so the view stays bright and focus works well. Canon's R50 manual notes that the screen therefore shows a shallower depth of field than the final photo, and that you can assign a depth-of-field preview button to check it. If you stop down to f/11 in aperture priority and the screen still looks shallow, that is why. The depth of field calculator gives you the near and far limits without guessing.

When to pick which

• Reach for aperture priority by default. Most shots are about depth of field, and it is forgiving.
• Switch to shutter priority when a specific shutter speed is non-negotiable: freezing a hummingbird, or smoothing a waterfall.
• Move to manual when you want the exact same exposure across many frames regardless of what the camera meters.

The exposure calculator shows how the camera trades one control for the other, which makes it easier to predict what each mode will do.

Common mistakes

• Ignoring the readout the camera chose. In aperture priority, a 1/10 shutter speed means blur. In shutter priority, a blinking aperture means the shot is over or under. Glance at it before pressing.

• Leaving ISO too low in a priority mode. The camera cannot invent light. If aperture priority keeps picking slow shutter speeds, raise ISO so it can pick faster ones. See ISO explained.

• Using shutter priority for portraits. You get a random aperture and unpredictable background blur. Use aperture priority instead.

• Thinking priority modes are not real photography. They are the same exposure decisions as manual, with one delegated to a computer that does it well.

• Forgetting exposure compensation exists. Both modes accept the plus/minus dial. Snow, white walls, and dark stages still fool the meter, so use exposure compensation instead of switching modes.

Is aperture priority or shutter priority better for beginners?

Aperture priority. Depth of field is the most common creative choice, the mode is forgiving, and you only have to watch one readout. Most experienced photographers use it as their default too.

What do Av and Tv mean on a Canon?

Av is aperture value (aperture priority) and Tv is time value (shutter priority). Nikon, Sony, and Fujifilm label the same two modes A and S.

Can I use auto ISO with aperture or shutter priority?

Yes, and it is a strong combination. You control the creative setting, the camera picks the other exposure control, and auto ISO fills any remaining gap so the shot stays bright enough.

Why is the aperture blinking in shutter priority?

The camera cannot find an aperture that gives a correct exposure at the shutter speed you chose. If the widest aperture is blinking, the scene is too dark: use a slower shutter or a higher ISO. If the smallest aperture is blinking, the scene is too bright: use a faster shutter, lower ISO, or add an ND filter.