March 26, 2019

For our final blog post we decide it was time for us to learn how to use a camera in manual mode. Where as in our previous blog posts we demonstrated how a camera could be used as an educational tool, this week we have learnt the basics of how to take pictures without using the highly convenient “auto” mode. The first step the learn how to do this we had to understand what aperture, shutter speed, and ISO actually do in a digital camera.

Aperture

The aperture refers to the how wide the shutter is opening and will affect how much light is being exposed to the sensor, but also the focal length of the photos you take. When you are in a very sunny environment not as much light is needed to reach the cameras sensor to create a picture, so using the aperture you can set the shutter to open only slightly. When taking a photo in a dark environment more light is needed to for the camera to be able to create a photo, so in this case you can set the aperture to be larger so the shutter will open more to let more light onto the sensor. For photos where only a smaller depth of field is desired, a larger aperture is needed. For example a close up photo of a plant or a portrait of someone. A smaller aperture is needed for photos of a larger area, such as a landscape photo, so everything in the frame will be in focus.

Aperture
Large aperture (f / 5.6)
Small aperture (f / 10.0)

Shutter Speed

Shutter speed is the speed of which the shutter is opening and closing. This can be used to take photos of thing moving very quickly making it appear if they are standing still, or using a long shutter speed will make water looks soft and blurred or cars long steaks moving across the entire photo. If your shutter speed is too slow your photo could be overexposed, or blurry if your subject moves. If it is too fast your photo may end up underexposed.

Fast shutter speed (1/2500 second)
Slow shutter speed (1/125 second)
Balanced shutter speed (1/500 second)

ISO

ISO is the measurement of how sensitive your camera sensor is to light. ISO 100 is a low sensitivity, and would be used in sunny conditions where the sensor does not need to be very sensitive to achieve the correct exposure. A lower ISO also shoots a very clear, non-grainy photo. A high ISO, such as ISO 3400, would be used in low light conditions, such as a dark museum, to increase the camera’s light sensitivity and multiply the smaller amount of available light.

High ISO (6400)
Lower ISO (200)

Triangle of Exposure

These 3 functions all have an effect on your photo and must always be in balance with one another. If you were to set your aperture to be more large to let in more light and also set your shutter speed to be very slow you may end up with a very overexposed photo like this.

The stats on this photo are F / 4.5, 1/4000, and ISO 6400. So in the case of this photo the aperture was letting in lots of light by opening the shutter very wide, and the shutter speed was very fast to match this and not let the shutter stay open too long, but the ISO was very high meaning the sensor was very sensitive to light. The ISO and the aperture were not matching in this photo so it turned out to be over exposed. To make this photo balanced we would have needed to lower either the aperture so less light came in the lens or lower the ISO the sensor was less sensitive to light. To create a normal photo the aperture, shutter speed and ISO must all be in balance to not have a photo that is over or underexposed.

f / 5.6, SS 1/4000, ISO 6400
f / 4.5, SS 1/1600, ISO 100
f/ 5.6, SS 1/3200, ISO 6400
f / 5.6, SS 1/2500, ISO 6400
f / 5.6, SS 1/320, ISO 400

Advertisements