I SEE F-STOPS ON MY 3D CAMERA, WHAT ARE THEY AND HOW DO I USE THEM?
Izzy Wood, Chesterfield
When there is an F-stop option on a 3D camera object, most often through the attribute or properties palette of an application, this is a setting which mimics those of real-world cameras. An F-stop (also known as an F-number) is the width of the hole (or aperture) that the aperture blades create in the camera lens. The bigger the hole, the ‘larger’ the F-stop number. The easiest way to read an F-stop value is to think of it like a fraction where an F-stop value of f/2 equals an aperture of approximately half the diameter of the lens. In contrast, an amount of f/16 creates a hole of roughly 1/16 the width of the lens.
The reasons photographers have this control on a lens is to do with two key factors. The first is that the larger the hole of the aperture, the more light photons can hit the sensors of a digital camera or film of a traditional camera. More light means cleaner images taken in less time than if the aperture was reduced.
The second key reason is that the larger the aperture, the less depth of field the image has. This means that with a larger aperture, the areas of the image that are not in focus are blurred out. This blurring, or bokeh, can be great for portraits where the focus is on an eye, but not so good for landscapes where everything needs to be in focus. For scenes like these, closing down the aperture to increase the depth of field is the best option.
Learning how F-stops work in 3D is an excellent way of learning how to create realistic-looking renders. For example, rendering a car with a large aperture, where a lot of the scene is blurred out,
could make it look like a model, as photographs of small objects tend to have blurred backgrounds due to the aperture of the lens and size of the sensor.
The best way to learn about aperture is to get a cheap, used DSLR or mirrorless camera with a 50mm equivalent lens with a large aperture of f/1.8 or similar. Then, take photos with different aperture values to see how this affects the images. Doing this will help you to understand the correct value to input into the 3D camera for the chosen scene.