Once you understand basic flash operation, these advanced techniques expand your creative control. This guide provides practical settings you can use immediately, then explains the theory behind them.
This guide assumes you've completed:
Quick Start: Practical Settings for Common Scenarios
Use these settings as starting points, then adjust based on results.
Fill Flash Outdoors (Softening Harsh Shadows)
| Setting | Value | Notes |
|---|---|---|
| Camera mode | Aperture priority or manual | Meter for ambient first |
| Shutter | At or below sync speed | Usually 1/125-1/250 |
| Flash mode | TTL -1 to -2 EV | Or manual at 1-2 stops under ambient |
| Distance | 2-4 metres typical | Closer = stronger fill |
Result: Sun remains the main light; flash gently opens shadows.
Dramatic Portrait (Flash as Main Light)
| Setting | Value | Notes |
|---|---|---|
| Camera mode | Manual | Full control needed |
| Shutter | Max sync speed (1/125-1/250) | Darkens ambient |
| Aperture | f/5.6-f/8 | Adjust for desired depth |
| Flash | Manual, 1/4 power | Start here, adjust |
| Distance | 2-3 metres | With modifier if possible |
Result: Subject lit by flash; background goes darker.
Indoor Event (Bounce Flash)
| Setting | Value | Notes |
|---|---|---|
| Camera mode | Manual or aperture priority | |
| ISO | 400-800 | Helps with bounce light loss |
| Shutter | 1/60 | Lets in some ambient |
| Flash | TTL, bounced at 45-degree angle | Aim at ceiling/wall junction |
Result: Soft, natural-looking light that blends with room ambience.
Motion Blur with Sharp Subject (Rear Curtain)
| Setting | Value | Notes |
|---|---|---|
| Camera mode | Manual | |
| Shutter | 1/15 to 1/4 second | Slow enough for blur |
| Flash sync | Second curtain / rear curtain | Check camera menu |
| Flash | TTL or manual | Freezes subject at end of exposure |
Result: Motion blur trails behind the sharp, flash-frozen subject.
High-Speed Sync (HSS)
What It Is
HSS lets you use flash at shutter speeds faster than your camera's normal sync speed. Instead of one flash burst, the flash fires rapidly like a strobe while the shutter travels.
When You Need It
- Shooting wide apertures (f/1.4-f/2.8) in bright daylight with flash
- Using flash at 1/500 or faster to freeze action
- Creating shallow depth of field outdoors with fill flash
The Problem HSS Solves
Without HSS, shooting faster than sync speed causes banding—a dark band across part of your frame where the flash didn't reach. This happens because the shutter curtains form a travelling slit at fast speeds, and the single flash burst only illuminates part of the frame.
What banding looks like: A distinct black or dark grey stripe across your image, usually horizontal. The stripe is sharp-edged and covers anywhere from 1/4 to 3/4 of the frame depending on how far over sync speed you shot.
How to Use HSS
- Enable HSS on your flash (often called "FP" or "high-speed" mode)
- Ensure camera and flash are compatible (TTL system required)
- Set your desired fast shutter speed
- Be aware: flash power drops significantly (2-3 stops)
HSS Quick Reference
| Situation | Without HSS | With HSS |
|---|---|---|
| Max shutter | 1/250 typical | Any speed |
| Flash power | Full available | Reduced 2-3 stops |
| Working distance | Normal | Reduced (move closer) |
| Compatibility | Any flash | TTL system required |
For Film Photographers
HSS requires electronic communication between camera and flash, which most older manual cameras lack. The practical alternative: Use a camera with a leaf shutter (Hasselblad, many rangefinders, view cameras). Leaf shutters sync at any speed because they expose the entire frame simultaneously.
First vs Second Curtain Sync
What It Is
This setting controls when the flash fires during a slow exposure—at the start (first/front curtain) or end (second/rear curtain).
The Visual Difference
First curtain (default): Motion blur appears in front of your subject. A moving person looks like they're walking backward because they're frozen at the start, then the blur extends forward as they move.
Second curtain: Motion blur appears behind your subject. The blur trails naturally behind, showing where the subject came from, then they're frozen sharp at the end.
When to Use Each
| Sync Mode | Best For | Visual Effect |
|---|---|---|
| First curtain | Static subjects, standard flash | Sharp subject, no motion consideration |
| First curtain | Fast ambient shutter (no blur) | No visible difference from second curtain |
| Second curtain | Moving subjects with blur | Natural-looking motion trails |
| Second curtain | Light painting, creative motion | Trails lead up to sharp subject |
How to Set It
- On camera: Look for "flash sync" or "curtain sync" in menu
- On flash: Some units have a dedicated switch
- Default: Nearly all cameras default to first curtain
Practical Example: Cyclist at Night
Goal: Show motion blur from bike lights trailing behind a sharp cyclist.
| Setting | Value |
|---|---|
| Shutter | 1/8 second |
| Aperture | f/5.6 |
| ISO | 400 |
| Sync | Second curtain |
| Flash | TTL or manual 1/4 power |
Process: Pan with the cyclist. The long exposure captures light trails and background blur, then flash fires at the end, freezing the rider sharply with trails behind them.
Mixing Flash with Ambient Light
This is the most powerful technique: controlling the balance between flash and existing light.
The Key Concept
Shutter speed controls ambient exposure. Aperture and flash power control flash exposure.
This works because flash duration is extremely short (1/1000s or faster). Changing shutter from 1/60 to 1/250 doesn't noticeably affect flash exposure, but dramatically changes how much ambient light reaches the film.
Step-by-Step Decision Process
Step 1: What do you want the background to look like?
- Natural brightness → meter ambient, use that exposure
- Darker/moodier → underexpose ambient by 1-2 stops
- Very dark → use max sync speed, may need ND filter
Step 2: Set your ambient exposure
- Meter the scene without flash
- Set shutter speed (stay at or below sync speed)
- Set aperture for desired ambient level
Step 3: Add flash for subject
- Set flash power so subject is properly exposed at your chosen aperture
- Use guide number calculation or flash meter
Step 4: Fine-tune the ratio
- More flash = subject brighter than background
- Less flash = subject blends with ambient
- Equal = balanced, natural look
Common Flash + Ambient Scenarios
Scenario A: Fill Flash in Daylight
Goal: Open shadows on a backlit subject while keeping natural sky exposure.
| Step | Action | Example |
|---|---|---|
| 1 | Meter background/sky | Reads f/11, 1/125 |
| 2 | Set camera to ambient | f/11, 1/125 |
| 3 | Set flash 1-2 stops under | Flash at f/5.6-f/8 worth of light |
| 4 | Result | Sky exposed normally, shadows lifted |
Scenario B: Dramatic Indoor Portrait with Window
Goal: Subject lit by flash, window visible but not blown out.
| Step | Action | Example |
|---|---|---|
| 1 | Meter window | Reads f/8, 1/125 |
| 2 | Underexpose slightly | Set f/8, 1/125 (or f/11 for moodier) |
| 3 | Set flash as main | Flash at f/8-f/11 for subject |
| 4 | Result | Properly lit subject, dramatic window glow |
Scenario C: Evening Event with Ambient Glow
Goal: Sharp subjects with warm ambient light visible.
| Step | Action | Example |
|---|---|---|
| 1 | Meter ambient | Reads f/2.8, 1/15 at ISO 400 |
| 2 | Set for blur-free ambient | f/4, 1/60 (2 stops under—ambient will be dim but visible) |
| 3 | Add flash | TTL or manual for correct subject exposure at f/4 |
| 4 | Result | Sharp subject, ambient warmth in background |
Troubleshooting Flash + Ambient
| Problem | Cause | Solution |
|---|---|---|
| Background too dark | Shutter too fast | Slow shutter to let in more ambient |
| Subject too bright | Too much flash | Reduce flash power or increase distance |
| Subject has two shadows | Flash and ambient both strong | Accept it, or make one light dominant |
| Colour mismatch | Flash is daylight, ambient is tungsten | Gel flash with CTO filter to match |
Manual Flash Power Control
What the Numbers Mean
Flash power is measured in fractions. Each step is one stop of light:
| Power | Light Output | Stops Below Full |
|---|---|---|
| 1/1 (full) | 100% | 0 |
| 1/2 | 50% | 1 |
| 1/4 | 25% | 2 |
| 1/8 | 12.5% | 3 |
| 1/16 | 6.25% | 4 |
| 1/32 | 3.125% | 5 |
| 1/64 | 1.56% | 6 |
Why Use Lower Power?
| Power Level | Recycle Time | Flash Duration | Best For |
|---|---|---|---|
| Full (1/1) | 3-6 seconds | ~1/500s | Maximum reach |
| 1/4 | <1 second | ~1/2000s | General use |
| 1/8 | Near instant | ~1/4000s | Fast shooting, action |
| 1/16 or lower | Instant | ~1/8000s+ | Freezing fast motion |
Key insight: Lower power = shorter flash duration = better motion freezing. For sharp action shots with flash, use lower power and move closer.
Practical Power Settings
| Scenario | Starting Power | Typical Distance | Aperture Range |
|---|---|---|---|
| Headshot, close | 1/8 - 1/16 | 1-1.5m | f/5.6-f/8 |
| Half body | 1/4 - 1/8 | 2-3m | f/5.6-f/8 |
| Full body | 1/2 - 1/4 | 3-4m | f/4-f/5.6 |
| Group | 1/1 - 1/2 | 4-6m | f/5.6-f/8 |
Based on GN 40 flash at ISO 100. Increase ISO or open aperture if using modifiers.
Multiple Flash Setups
Triggering Methods
| Method | Pros | Cons | Best For |
|---|---|---|---|
| Sync cords | Reliable, cheap | Cables tangle, limited mobility | Simple two-light setups |
| Optical slaves | No wires, cheap | Fails in bright light, TTL pre-flash issues | Indoor, controlled environments |
| Radio triggers | Reliable anywhere, no line-of-sight | Cost, batteries needed | Professional, outdoor work |
Simple Two-Light Setup
Goal: Portrait with main light and hair/separation light.
| Light | Position | Power | Modifier |
|---|---|---|---|
| Key (main) | 45 degrees to side, slightly above | 1/4 | Umbrella or softbox |
| Hair/rim | Behind subject, opposite side from key | 1/8 | Bare or grid |
Ratio: Key is 1 stop brighter than rim (2:1 ratio).
Controlling Ratios
The ratio between lights controls contrast. Set it by adjusting power:
| Desired Ratio | Key Power | Fill/Rim Power | Look |
|---|---|---|---|
| 1:1 (equal) | 1/4 | 1/4 | Flat, even |
| 2:1 (1 stop) | 1/4 | 1/8 | Gentle contrast |
| 4:1 (2 stops) | 1/4 | 1/16 | Dramatic |
| 8:1 (3 stops) | 1/4 | 1/32 | Very dramatic |
Always start with one light and get it right. Add the second only when you understand what the first is doing. This prevents confusion and teaches you what each light contributes.
Bounce and Modifier Techniques
Quick Bounce Reference
| Bounce Target | Light Character | Light Loss | Watch For |
|---|---|---|---|
| White ceiling | Soft, overhead | 2-3 stops | Racoon eyes if ceiling high |
| White wall (side) | Soft, directional | 2-3 stops | Colour cast if wall isn't neutral |
| Ceiling/wall corner | Very soft, wrap | 3+ stops | Significant power needed |
| Bounce card on flash | Soft, forward fill | 1-2 stops | Still somewhat direct |
Modifier Light Loss
Account for this when calculating exposure:
| Modifier | Typical Loss | Effective GN Multiplier |
|---|---|---|
| Bare flash | 0 stops | 1.0 |
| Shoot-through umbrella | 1-1.5 stops | 0.7 |
| Reflective umbrella | 1.5-2 stops | 0.5-0.6 |
| Small softbox (60cm) | 1.5-2 stops | 0.5-0.6 |
| Large softbox (90cm+) | 2-2.5 stops | 0.4-0.5 |
| Beauty dish | 1-1.5 stops | 0.7 |
Coloured Surface Warning
Bouncing off coloured surfaces tints your light. This is obvious on colour film, less so on black and white.
- Yellow/cream ceiling → warm/yellow cast
- Green wall → sickly green tint
- Wood panelling → orange/brown cast
Solution: Use a modifier instead, or accept the colour cast (sometimes warm fill looks natural).
Film-Specific Considerations
Colour Temperature Matching
| Ambient Light | Film Type | Flash Treatment |
|---|---|---|
| Daylight | Daylight film | No gel needed |
| Tungsten (indoor) | Daylight film | Accept mixed colour or gel flash with CTO |
| Tungsten (indoor) | Tungsten film | Gel flash with full CTO |
| Mixed | Either | Gel flash to match dominant source |
Flash with Slide Film
Slide film has minimal exposure latitude. Flash helps because output is consistent.
Tips:
- Use a flash meter for critical work
- Bracket if uncertain (1/2 stop increments)
- Check Polaroid/test first if possible
Flash with Black and White
Black and white is forgiving and colour-blind:
- No colour temperature concerns
- Higher contrast ratios often work well
- Focus on tonal separation, not colour
Technical Reference
This section covers the underlying theory for those who want to understand the math and physics.
Guide Number Deep Dive
The Formula:
Guide Number = Distance x Aperture (at ISO 100)
Rearranged:
- Aperture = GN / Distance
- Distance = GN / Aperture
Example with GN 40:
- At 5m: 40 / 5 = f/8
- At 2.5m: 40 / 2.5 = f/16
- At 10m: 40 / 10 = f/4
ISO Adjustment for Guide Numbers
Guide numbers are specified at ISO 100. For other ISOs, the effective GN increases:
| ISO | GN Multiplier | GN 40 Becomes |
|---|---|---|
| 100 | 1.0 | 40 |
| 200 | 1.4 | 56 |
| 400 | 2.0 | 80 |
| 800 | 2.8 | 113 |
| 1600 | 4.0 | 160 |
Formula: New GN = Base GN x square root of (New ISO / 100)
Or think in stops: Each stop of ISO lets you close down one stop or double distance.
Full Exposure Calculation Example
Situation: GN 40 flash, ISO 400, through 90cm softbox, subject at 2 metres.
| Step | Calculation | Result |
|---|---|---|
| 1. ISO adjustment | GN 40 x 2.0 (for ISO 400) | GN 80 |
| 2. Softbox loss | GN 80 x 0.5 (2 stops loss) | Effective GN 40 |
| 3. Calculate aperture | 40 / 2m | f/20, round to f/16 |
Sync Speed Technical Explanation
Focal plane shutters use two curtains travelling across the film:
- First curtain opens, beginning exposure
- At slow speeds, frame is fully uncovered, flash fires
- Second curtain closes, ending exposure
At speeds faster than sync, the second curtain begins closing before the first fully opens. A slit travels across the frame—no moment exists when the entire frame is exposed. Flash during this creates partial exposure (banding).
Sync Speeds by Camera Type
| Camera Type | Typical Max Sync | Notes |
|---|---|---|
| Older mechanical SLR | 1/60 | Horizontal cloth shutter |
| 1980s electronic SLR | 1/125 | Improved mechanisms |
| Modern SLR | 1/200-1/250 | Vertical metal blades |
| Leaf shutter cameras | Any speed | No slit travel |
| Medium format (FP shutter) | 1/60-1/125 | Large curtain travel distance |
| Medium format (leaf shutter) | Any speed | Lens-based shutter |
| Large format | Any speed | Lens-based shutter |
Summary
Quick wins:
- Use the Quick Start tables as starting points for common scenarios
- Second curtain sync makes motion blur look natural
- Lower flash power = faster recycle and better motion freezing
Key concepts:
- Shutter controls ambient; flash power/aperture controls flash exposure
- HSS allows fast shutter speeds but costs 2-3 stops of power
- Build multi-light setups one light at a time
When in doubt:
- Start with flash at 1-2 stops below ambient for natural fill
- Use bounce for softer light (budget 2-3 stops for ceiling bounce)
- Check your camera's sync speed before shooting—banding ruins frames
Practice each technique individually before combining them. The goal is to have these become instinctive so you can focus on your subject, not the calculations.