Understanding Diffusion: The Core Theory

When it comes to diffusion, distance and density are everything. A few rules of thumb:

• A 4x diffusion 3’ away from your subject gives a similar softness as a 12x diffusion 12’ away. Size and distance matter.

• A 12x diffusion 12’ away has a similar effect as a 20x diffusion even farther back.

• The thicker the diffusion or the closer it is, the softer the light will wrap.

However, Inverse Square Law plays a role too. The farther your diffusion is, the more natural your falloff — preserving that believable sunlight feel instead of creating an artificial flat wash.

The goal for a sunlight look is usually to take the hard edge off without over-softening. Let the light still feel like sunlight.

Step 1: Sun Position Comes First

Before you even pull the diffusion rags out, sun orientation is your #1 variable.

• Backlight whenever possible. ¾ backlight is ideal — it gives you a motivated fill side and looks most natural.

• Avoid full frontal sun unless the creative demands it (harsh, hot, midday looks).

• Schedule wider shots for early morning or late afternoon when the sun is lower.

• Use high noon for closeups that you can control with diffusion and flags.

Some high noon light shaping

Front light might be ugly… unless your creative demands that harsh, scorched look. Sometimes breaking the rules works.

Tools like Sunseeker are invaluable for scouting and planning your shot list based on the sun’s path.

Step 2: The Diffusions We Use

Let’s break down the tools, from lightest to heaviest, and when to use them:

Hampshire Frost

• Great for softening backlight without flattening.

• Roll-only (4x4, 4x8 frames or cuts).

• Best used for slight edge control, not direct frontal sunlight.

• Light reduction: <¼ stop.

3/4 frontal and backlit hampshire diffusion comparison

Opal Frost (Lee 410)

• Go-to for softening nose shadow without killing shape.

• Comes only in rolls (skinned 4x frames, barn doors, waterfalled off roll).

• Tears easily — reinforce with J-lar tape.

• Light reduction: ~½ stop.

3/4 frontal and backlit opal diffusion comparison

Highlight

• Similar feel to Hampshire but available in rag sizes.

• Quiet in wind.

• My most used rag for 8x and 12x frames.

• Light reduction: ⅔ stop.

½ Soft Frost

• Vinyl material, blooms beautifully without feeling fake.

• Allows sheen and specularity to come through.

• Often paired with nets to balance bloom.

• Light reduction: 2 stops.

3/4 frontal and backlit 1/2 soft frost diffusion comparison

¼ Grid Cloth

• More directional softness, heavier than previous options.

• Works well for larger frames further back.

• Silent options for wind.

• Light reduction: ~1⅔ stops.

3/4 frontal and backlit 1/4 grid cloth diffusion comparison

Silks (¼ Silk, China Silk, Full Silk/Polysilk)

• Used for broad overhead diffusion.

• ¼ Silk is thinnest; China Silk great for full street backlot coverage.

• Full Silk (Polysilk) is the densest.

• Best when covering entire environments; not ideal for small area work.

• Light reduction: ~1 stop for ¼ Silk.

Overhead diffusions on a back lot

Step 3: Match Your Frame Size to Your Coverage Area

Small Coverage (4x Frames)

• Mostly for closeups.

• Play the 4x frames closer to subject.

• Avoid thick diffusions here — too much softness feels fake.

• Typically: Opal, Hampshire, or ½ Soft Frost.

Shaping light with 4x4 frames

Medium Coverage (8x–12x20 Frames)

• Great for cowboy shots, mid shots, and tighter scenes.

• Allows for multiple subjects or wider lenses.

• I often use Highlight or ½ Soft Frost here.

• 8x/12x allows for distance while preserving the natural feel.

12x12 1/2 soft frost diffusing the low sun

Large Coverage (20x and Bigger)

• Larger frames benefit from slightly heavier diffusion to maintain coverage across distance.

• You may step up 1–2 grades in density vs smaller frames.

• Commonly used: Grids, Silks, ½ Soft Frost, ¼ Grid.

• Often used for full backlot, large streets, or group scenes.

Flyswatter diffusion with a dutchman

The Secret Formula (for Natural Daylight Look)

Here’s the core approach I use over and over for controlled, beautiful exteriors:

1. Orient subject to ¾ backlight.

2. Diffuse the backlight with Hampshire (4x) or ½ Soft Frost (8x+).

3. Bounce from the fill side with 12x Bleached Muslin ~12’ from subject.

4. Negative fill on opposite side to control sheen and wrap.

5. Add soft frontal eye light next to bounce for control (can go bigger like 8x8)

The secret sauce

If you nail sun position, you can often light with just a simple bounce.