Simon's background is in biomedical and health science. He also writes about fashion, nature, and photography.
The Exposure Triangle
Before you can shoot in manual mode, it's important that you have a basic understanding of what affects exposure. Exposure is when you capture or make a photo with your camera. This involves light striking the sensor in your camera. There are three things that control the amount of light that reaches the sensor: aperture, shutter speed, and ISO (International Organization for Standardization).
The aperture is the opening or hole in your lens that allows light to reach the camera's sensor. Think of the aperture like the pupil of the eyes. The pupil lets light into your eyes so that it can reach the retina. Just like the pupil of your eyes, the aperture of a camera can be varied to let in more or less light. The size of the aperture is indicated by f-stops. It usually ranges from f/2.8 to f/22. The higher the f-stop, the smaller the opening and as a result less light reaching the sensor. This may be difficult to grasp. Think of the f-stop as a fraction. The bigger denominator (bottom number), the smaller the value, and therefore smaller opening.
The aperture is also important for controlling depth of field. Depth of field is the extent of your photo that is in sharp focus. You can have a narrow or shallow range of your photo be in focus. To achieve this, you need to have a large aperture, or small f-stop, lower than f/4. For a deep depth of field, where everything from foreground to background is in sharp focus, you need a small aperture. This means you need a large f-stop, usually greater than f/8.
There is a shutter or curtain in front of your camera sensor. Think of this shutter like your eyelids. When you close your eyelids, no light enters your eyes. When you open your eyelids, light can enter. In your camera, the shutter can be opened to let light reach the sensor. The shutter speed is the amount of time this curtain or shutter is open. It ranges from 30 seconds (slow shutter speed) to 1/4000 second (fast shutter speed). Faster shutter speeds will let in less light.
When you have moving subjects, and want to either freeze or create blur in your photos, you must control the shutter speed. Shutter speeds faster than 1/500 second will freeze motion. Slower shutter speeds will produce blur.
The ISO controls the light sensitivity of your camera's sensor. It ranges from 100 to 6400. Increasing the ISO makes the sensor more sensitive to light. This means that you can get by with less light. So you can use a faster shutter speed or smaller aperture to compensate for the increased light sensitivity.
Step 1: Switch to Manual Mode
The first thing you need to do to shoot in manual mode is to turn your shooting mode to Manual. You will find a round dial on top of your camera with letters on it. Turn it to select the letter "M" for Manual. When you're in manual mode you can control the aperture, shutter speed and ISO. This gives you enormous power and creative control.
I will be using a Canon T5 camera to demonstrate shooting in manual mode. Other cameras will likely have similar controls.
Shooting Mode Dial and Main Dial
Step 2: Set the ISO
The first thing you should set is the ISO. You should set it to 100 to get the best image quality. You only need to increase the ISO if you are not getting enough light. This can happen in low light situations like at night or inside a house. Or when your combination of aperture and shutter speed is not giving you a correct exposure (getting correct exposure is explained further below). ISO values over 800 will result in noise in your images so try not to go over this value.
To change the ISO, you have to press the ISO button, and select the ISO you want using the left and right keys, and then press the SET button.
Step 3: Set the Aperture
Before you take a picture, decide what depth of field you want. Do you want everything to be sharp (deep depth of field) or just a small area or range to be sharp (shallow depth of field). If you want a deep depth of field select a small aperture of f/8 or greater. For shallow depth of field, select a large aperture of f/4 or smaller.
To change the aperture, you must press and hold the aperture (Av) button on the back while turning the main dial. To me this particular camera was almost set up to let you first select depth of field by choosing an appropriate aperture. Then all you have to do is turn to the right shutter speed to give you a correct exposure.
Aperture and ISO Button
Step 4: Set Shutter Speed
The final step to getting a great properly exposed photo is setting the shutter speed. Changing the shutter speed is quite easy. All you have to do is turn the main dial. You want to turn the main dial until you get a correct exposure.
To do this, you will have to look at the exposure level indicator or the meter in the back of the camera, or in the viewfinder. To see the meter, you may have to press the shutter button to the first stop. It looks like a ruler with -3 on the left, 0, in the centre, and +3 on the right. Negative values mean there is not enough light and the photo will be underexposed (see underexposure photo). Positive values mean there is too much light and the photo will be overexposed (see overexposure photo). What you want is the correct exposure, which is at 0. So turn your main dial to adjust the shutter speed so that the little bar or tick is at 0 (see correct exposure photo). This will give you the right exposure.
You can also play around with the exposure. If you want a darker image, use a faster shutter speed so the tick goes to -1. If you prefer a brighter picture, use a slower shutter speed so that the tick is at +1.
Step 5: Adjust ISO if Needed
You may encounter situations where you will need to increase the ISO. For instance, if you set the aperture to f/16 and you find that your shutter speed setting is giving you a slightly underexposed image. You can increase the ISO to higher number. This will increase your exposure and give you the proper exposure you need.
Or there may be times when you may need to use a faster shutter speed to freeze motion. Increasing the ISO will allow you to use a faster shutter speed so that you can freeze motion.
Step 6: Take the Picture
Once you get the correct exposure or the exposure you want, take the picture. To do this, press the shutter button all the way down.
Summary of Steps
To shoot in manual mode, make sure you have switched the shooting mode to Manual or M. Set the ISO first, ideally to 100. Then set the aperture. Use a large aperture if you want swallow depth of field. Use a smaller aperture if you want deep depth of field. Then adjust the shutter speed so that you get the correct exposure. This is indicated on the meter as being in the centre.