A comprehensive visual guide to equivalent exposure

If you’re just starting out with photography, the relationship between ISO, aperture and shutter speed is one of the crucial things to learn. However, it can be difficult to grasp if the concept is new to you. In this great animated video from Apalapse you’ll easily learn the relationship between the three parameters and how they affect the exposure and the look of your images.

Shutter speed, aperture, and ISO are three “ingredients” that all photos are made of. Shutter speed determines the amount of motion blur, aperture determines the depth of field, and ISO determines the amount of noise in your images. When you set the camera to manual mode, you get to choose what settings work best for your situation and thus you control the exposure and the overall look of your image.

Equivalent exposures

In the video, you can see a very comprehensive explanation of what equivalent exposures are, but I’ll try to sum it up briefly.

Let’s say you want to photograph a flower and the settings of f/8, ISO 100 and shutter speed 1/250 s will give you an image with correct exposure. However, while the exposure is right, the look of your image isn’t what you wanted – it doesn’t have a shallow depth of field.

To change this, you can open the aperture, let’s say to f/2.8. But, if you leave the other settings intact, the image will be extremely overexposed. If the minimum ISO on your camera is 100 (like it is on mine), you can’t decrease it any further. So, you’ll need to increase the shutter speed. The aperture is increased by 3 stops, so you’ll need to adjust the shutter speed for the same number of stops: from 1/250 to 1/2000.

The look of the image

As you adjust the three parameters, it won’t only affect the exposure, but also the look of your images. The more you open the aperture, the shallower depth of field you’ll get. The more you increase the ISO, the more noise there will be. And finally, the more you slow down the shutter speed, the more motion blur there will be. So, you should make sure to set the parameters to get the optimal exposure as well as the optimal amount of noise, sharpness, and depth of field.

I tried to sum it up, but make sure to watch the entire video. It’s filled with examples and illustrations that make things clearer. And if you want to learn more about how ISO, aperture and shutter speed affect your images, on this link you’ll find plenty more useful resources.

[Camera Basics – Equivalent Exposures via FStoppers]