3D World

basics: camera lenses

For the next instalment of our Basics series, let’s start exploring the camera

- Mike Griggs Mike Griggs is a 3D and visual effects artist with vast experience across the industry, as both a creator and a technical writer. www.creativebl­oke.com

Which lens is best for the job?

If you’re new to CGI, you may feel that there are far too many tools to choose from in a dizzying array of software. This series aims to break everything in CGI down to the very basics, so that every artist can be armed with the knowledge of which tool is best. This month we start our look at cameras and lenses.

The camera is probably the single most important tool in the world of CG. It is more important than modelling and animation and if the camera is pointing the wrong way, even the lighting won’t be seen. Therefore, mastering how 3D software handles camera manipulati­on is crucially important.

Over the next few instalment­s of the Basics series we will look at the various functions of cameras in digital content creation. To start with, let’s examine the definition of a camera in CG.

One of the most common assumption­s for a new artist working in CG is that the perspectiv­e view is the camera. While ‘technicall­y’ true as the software has created a virtual camera to view the scene in the viewport, this is not the same as an actual camera object.

A camera object is usually identified as a film-style camera wireframe in the viewport, and typically has a properties palette full of informatio­n which makes it analogous to real-life cameras.

The most important of these factors is the focal length informatio­n, as this determines the zoom or field of view (FOV), and this dictates what the camera is seeing. Learning about focal lengths and how they can be used for scene manipulati­on is incredibly important for making shots believable in terms of scale, and once this has been mastered it can become a great tool for manipulati­ng images for more fantastica­l briefs.

Most CG cameras default at a focal length of around 35mm, which is a very common focal length for cameras as a ‘do all’ solution. However, if the scene is of a portrait of a CG head bust for example, then a 80-100mm focal length would be more suited, as the longer a focal length the less perspectiv­e distortion occurs, making the bust look more realistic.

Naturally the best way to learn about focal lengths is to use an actual camera, and this knowledge will easily transfer to your CG projects.

01 Viewport CAMERA

Although most digital content creation applicatio­ns allow rendering in any viewport, this is not the same as having an actual camera object. A camera object usually has a lot more options for controllin­g focal length, and as it is an actual ‘object’ in the scene it makes animating it a lot easier. Some applicatio­ns allow the default front, top and side cameras to actually be seen and exported, but be mindful of these as usually they are best kept hidden.

02 Wide-angle lenses

Wide-angle lenses (which tend to be classed as anything lower than 35mm) are good for wider scenes as they can catch a lot more detail. They are not great for close-up work as they distort features, so are unflatteri­ng for character work. Extreme wide-angle lenses are common in architectu­ral work, but be mindful to straighten vertical lines; this effect can be achieved with tilt-zoom lenses, commonly used in high-end architectu­ral photograph­y, but can be re-created easily in software.

03 telephoto lenses

Lenses that are longer than 50mm tend to be called telephoto lenses and are commonly used for character and close-up work, but they also tend to be used for macro work. Most portrait work is done in the 80-100mm range.

Additional­ly, long telephoto lenses in the 150-200mm range can be great for certain types of scenes as they can be used to create interestin­g contrasts between the foreground and background.

04 using Zoom lenses

Zoom lenses are often seen as the ‘poor cousins’ of prime lenses which have a single focal length, but good use of zoom lenses in a scene can be a great way of achieving some creative effects and looks. The ground-breaking spaceship work in the TV reboot of Battlestar Galactica depended on zoom lenses, and they can be used to create a dolly zoom effect – a technique in which there is an object in the centre of the screen while the background appears to zoom in or out.

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