O5 The finishing order, like a real camera · Lab

1 The idea

Light passes through the lens first (scatter, glow, colour fringing, vignetting) and only then hits the sensor (grain), so the nodes should follow that order. Put grain before the lens steps and they change it: the CA resamples the red and blue grain and softens it, and a blur or defocus smears it, which no real camera does. A glow that only spreads values above its threshold barely touches grain, so don’t judge the order by the glow alone.

This chain is in the right order. Adjust one step at a time and view each node.

2 Hands-on in the mini compositor

SkyVFX mini compositor · O5640×360 · float · 1001

3 Deep dive

Follow the path of the light

Light from the scene passes through any filter on the lens, then the glass, and only then reaches the film or sensor. Meanwhile the whole camera can shake. So the nodes at the end of the comp follow that order: what happens first sits higher, what happens later sits lower. Whether something goes before or after the shake depends on one question: is it pinned to the frame or to the picture? Pinned to the frame (CA and vignette are centred on the lens axis, grain sits on the sensor): after the shake, or it would shake with the image. Pinned to the picture (a flare placed on a light’s track): before, so it moves with the image. A glow, diffusion or halation worked out from the image itself comes out almost the same on either side of a shake, so it simply goes where this chain puts it.

1Diffusion
2Flares + glints
3Camera shake
4Chromatic aberration
5Halation
6Grain

Stage	Where it happens	What it looks like
Diffusion	Filter or smudge on the lens	Whole image slightly soft, blacks blend
Flares + glints	Light bouncing between lens elements	Ghosts and star rays from sources
Camera shake	The camera body moving	The whole frame moves together
Chromatic aberration	Lens glass	Colour fringes towards corners
Halation → Grain	Film or sensor	Red rims on highlights, grain

What comes before the camera stack

Defocus happens per layer, while the layers are still separate. The main comp glow goes on once, over the whole frame, after everything is merged and before the camera stack. Something extreme, like an explosion flash, can come in after the main glow so its own glow is controlled separately.

Diffusion is not glow: glow comes from highlights, while diffusion acts on the whole image, a big blur mixed in very low. It helps the CG blacks and plate blacks blend. Our lab shortens all this to glow → CA → vignette → grain to show the principle. If you redistort for the lens, the vignette goes after the distortion.

1Defocus per layer
2Merge everything
3One main glow
4Camera stack

Halation: red rims around highlights

On film, very bright light passes through the emulsion and bounces back off the film base. The layer nearest the base is the red-sensitive one, so a red-orange glow appears around blown highlights, mostly at bright-against-dark edges. Red spreads the widest.

How: pick only the truly blown highlights, blur them with red spreading widest, and add only the extra: (blurred − original), clamped at 0. Don’t add it to every shot; add it when the reference shows it, and leave out lights that are already red, or the red doubles.

Digital cameras show little halation; on a digital show, treat it as a deliberate look

Grain: last, and only once

Grain happens at the sensor, the last thing that happens to the picture. Anything after it blurs, moves or recolours the grain, which no camera does. After grain you may only crop for delivery. Do any resolution change before the regrain, and never grade after it.

The usual way: degrain the plate, comp on the clean plate all the way down, and regrain once at the end (then put the original plate back outside the new elements; see I4). The defocused desert then has grain as crisp as the in-focus robot, because grain never went through the lens.

Always judge the shot through the full end stack. A very saturated FX element can settle in once grain and diffusion are on, and something that looked fine without them can look off with them.

1Degrain the plate
2Comp on the clean plate
3Camera stack
4Regrain once
5Crop / Write

4 In real work

In Nuke

Keep the camera stack in one backdrop at the bottom of the script, ordered top to bottom.
Diffusion: a very large Blur merged back at a very low mix; check with the viewer gain up.
Flare and Glint nodes tied to the light source’s track, then Merge plus.
Halation: Keyer on the highlights → Blur with red widest → Merge minus the original → Clamp minimum 0 → Merge plus.
Grain (or a third-party regrain gizmo such as DasGrain) as the last node before the crop and the Write.

Common mistakes → the fix

✗ Grain before the defocus, a blur or the lens steps✓ Grain goes last, or those steps blur or resample the grain too.
✗ Adding grain twice, on the element and again on the comp✓ Once, at the end; original plate areas must not get it twice.
✗ Grading after the grain✓ Grade before the grain so its strength matches the final brightness.
✗ Halation on every shot by default✓ Only when there are truly blown highlights and the reference shows it.
✗ CA before the camera shake✓ CA is pinned to the frame (centred on the lens axis, which moves with the camera), so it goes after the shake and stays centred on the frame.

Before you send the shot

Order: diffusion → flares/glints → shake → CA → halation → grain
One main glow, before the camera stack
Grain once, the last node before crop/Write
Defocused areas still have crisp grain
Any halation sits only around truly blown highlights
The shot was reviewed with the full stack on

5 Check yourself

One question to check yourself

What happens if grain moves above the lens steps (glow, CA, vignette)?

What you learned

🔒 Answer the question above and this card opens