Senior Compositor

Derek Rein

https://derekvfx.ca

As light passes through a cameras lens, a number of artifacts are generated. Matching these when integrating with a photographed plate or adding when compositing a full-cg shot is essential to selling the photorealism of your work. Individually each lensing effect will not 'complete the picture' but rather a complete and accurate lensing setup will be greater than the sum of its parts. Every compositor should have some understanding of photography and how light interacts with a lens.

Lensing should always be applied as a last step when compositing, and roughly in the logical order that would follow inside a physical camera.

Depth of Field

zDefocus and the pgBokeh

For simple

Most render engines have the ability to calculate depth of field, this approach is slow and irreversible.

Diffraction

Caused by physical impurities in the materials that comprise the lens. It's why else cinematographers pay huge sums of money for expensive lenses. It's mostly to avoid.

Vignette

Vignetting is caused by the physical dimensions of a multiple element lens. Rear elements are shaded by elements in front of them, which reduces the effective lens opening for off-axis incident light. The result is a gradual decrease in light intensity towards the image periphery.

Light falls off with the inverse square of the distance form the source.

falloff = ((d/ƒ)^2

Lens Distortion

Most large studios include lens distortion as part of their VFX pipeline where the lens distortion of every lens used on a show is measured and published. Otherwise you can use the LensDistortion node to analyze either manually or with a photographed lens grid or automatically by tracking points through a shot.

Curvilinear Lens

Most footage that you will be working with has been shot on a curvilinear lens,

Rectilinear Lens

A synthetic lens inside a 3D dag software will always have a

Apply lens distortion to 3d, never to your footage.

Lens Flare

The defacto solution for generating lens flares in Nuke and After Effects is the powerful OpticalFlares plugin. It's caused by reflections between different elements inside the lens.

Fringing

High contrast areas

Chromatic Aberration

Chromatic aberration, also known as color fringing, is a color distortion that creates an outline of unwanted color along the edges of objects in a photograph. Often, it appears along metallic surfaces or where there's a high contrast between light and dark objects, such as a black wall in front of a bright blue sky.

https://photographylife.com/what-is-chromatic-aberration

Matte Box Effects

Promist

A common matte box effect

Grain

Grain should always be applied as a final step in any composite.