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Want to get out of Auto mode and have great exposures? You need to understand the big 3 camera settings below.

Aperture, Shutter Speed, and ISO

These are the 3 most important camera settings to understand when venturing out of Auto mode on your camera.

These 3 camera settings determine the exposure of your photo. You must understand them to effectively use Manual mode (and others) on your camera.


Technically the aperture is the opening in the lens that controls how much light hits the camera sensor.

If you want to only adjust aperture, choose Aperture Priority mode.

Aperture determines the depth of field and the exposure.

Depth of Field

Your depth of field determines how much of your photo is in focus.

A shallow depth of field will only have objects close to the camera in focus, while a deep depth of field will have objects both close and far away in focus.

Generally the apertures you will use range from f/1.4 to f/22. These are referred to as f-stops.

Smaller f-stops like f/1.4 signify a larger opening which will create a shallow depth of field. Larger f-stops like f/22 signify a smaller opening which will create a deeper depth of field.

Different lenses have different aperture ranges so you may need multiple lenses to cover the different apertures you want. I currently have an 18-55mm lens that goes from f/4 to f/22 and a 50mm lens that goes from f/2.5 to f/32.

Shallow depth of field is often used in macro photography and portrait photography to get blurry backgrounds and the bokeh effect. For my senior photo, I used the lowest aperture I could, which was f/2.5. I wish I had purchased a lens that went down to either f1.4 or f/1.8 but it still worked out.

My Senior Portrait


Aperture helps control the exposure by controlling how much light is let in through the opening.

If you kept the shutter speed the same but changed the aperture, shooting at a larger f-stop (f/22) would produce a darker photo than shooting at a lower f-stop (f/1.4).

Shutter Speed

Your shutter speed determines how long the shutter of your camera is open.

A longer shutter speed will let in more light than a shorter one. The general range is anywhere from 1/4000 of a second to 30 seconds. If you want more control, try using bulb mode where the shutter is open as long as you press and hold down on it.

If you want to only adjust shutter speed, choose Shutter Priority mode.

Aperture and shutter speed work inversely with each other. To maintain a good exposure you have to adjust each camera setting accordingly. If you decrease your shutter speed, you must increase your aperture by changing it to a smaller number. It’s a little confusing how the smaller f-stop numbers signify a larger aperture but you’ll get the hang of it eventually.

If you want to capture a moving object, like a car or person running, use a shorter shutter speed. If you want to blur motion, like smooth waterfalls or light trails, use a longer shutter speed.

A neutral-density filter (ND filter) can help with long exposures during the daytime. It reduces the intensity of the light entering the camera, enabling you to get properly exposed photos with a longer shutter speed, even if there’s a decent amount of light.


Finally, ISO is the measure of how sensitive your camera’s sensor is to light.

If you are using a film camera, it measures how sensitive your film is to light. I’ve only ever used ISO 400 film which is good for outdoor shots with varying amounts of sunlight.

ISO generally varies from 100 to 6400 in digital cameras. My Canon Rebel T7i goes all the way up to 25600 which I doubt I’ll ever need to use.

Generally, your camera will try and keep your ISO low, around 100, to avoid adding grain to your photos.

When shooting in darker places, it may be necessary to increase your ISO if you want to maintain your shutter speed and aperture so the camera sensor can capture more light.

ISO can also be an important factor in long exposure photography, especially with photos at night, such as light trails. Keep the ISO low during the long exposure to reduce the amount of grain.

Red light trails going over a bridge

If you want to learn more about how to create light-trail photos like this one, check out my guide on light-trail photography.


If you want more information on these 3 camera settings, check out these articles by Photography Life on aperture, shutter speed, and ISO.

To learn more about the different camera modes and when to use them, check out my helpful guide.

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