Exposure Calculator
Calculate equivalent exposure settings and exposure values for photography.
Exposure Settings
Current Settings
New Settings
New Shutter Speed
1/500
f/2.8 • ISO 100
Exposure Comparison
Exposure ValueEV 11.9
Aperture Change+2.0 stops
ISO Change0.0 stops
Shutter Compensation+2.0 stops
Understanding the Exposure Triangle
The exposure triangle is the fundamental concept in photography, consisting of three interconnected settings that control how much light reaches your camera's sensor: aperture, shutter speed, and ISO. Mastering this relationship is essential for achieving proper exposure and creative control.
| Setting | What It Controls | Creative Effect | Trade-off |
|---|---|---|---|
| Aperture (f-stop) | Amount of light through lens | Depth of field | Wide = shallow DOF; narrow = deep DOF |
| Shutter Speed | Duration of light exposure | Motion blur/freeze | Fast = freeze motion; slow = blur motion |
| ISO | Sensor sensitivity | Low-light capability | High = more noise; low = cleaner image |
| Scenario | Aperture | Shutter Speed | ISO | Result |
|---|---|---|---|---|
| Bright daylight portrait | f/2.8 | 1/1000s | 100 | Blurred background, frozen subject |
| Landscape, deep focus | f/11 | 1/125s | 100 | Everything sharp, tripod optional |
| Indoor event | f/2.8 | 1/125s | 1600-3200 | Usable shutter, moderate noise |
| Night street | f/1.8 | 1/60s | 3200-6400 | Handheld possible, some noise |
| Sports action | f/4 | 1/1000s+ | 400-1600 | Frozen action |
- Aperture: Controls depth of field (how much of the scene is in focus)
- Shutter Speed: Controls motion blur (freeze or show motion)
- ISO: Controls sensor sensitivity (affects image noise)
- Changing one setting by 1 stop requires adjusting another by 1 stop to maintain exposure
Exposure Triangle Relationship
Exposure = (Aperture × Shutter Speed) / ISO
Where:
- Aperture= f-number (f/2.8, f/4, f/5.6, etc.)
- Shutter Speed= Duration in seconds (1/125, 1/250, etc.)
- ISO= Sensor sensitivity (100, 200, 400, etc.)
Exposure Value (EV) System
Exposure Value (EV) is a single number that represents a combination of camera settings producing equivalent exposure. Understanding EV simplifies exposure compensation and helps with light metering.
| EV at ISO 100 | Lighting Condition | Typical Settings |
|---|---|---|
| -4 to -2 | Starlight, Milky Way | f/2.8, 20-30s, ISO 3200+ |
| -1 to 1 | Full moon, cityscape at night | f/4, 2-8s, ISO 800 |
| 2 to 4 | Street lighting, Christmas lights | f/2.8, 1/30s, ISO 1600 |
| 5 to 7 | Home interior, stage lighting | f/2.8, 1/60s, ISO 800 |
| 8 to 10 | Sunrise/sunset, bright indoor | f/5.6, 1/125s, ISO 400 |
| 11 to 13 | Overcast day, open shade | f/8, 1/250s, ISO 200 |
| 14 to 15 | Sunny day (Sunny 16 rule) | f/16, 1/100s, ISO 100 |
| 16+ | Bright sun on snow or sand | f/16, 1/500s, ISO 100 |
- Each EV step represents doubling or halving of light
- EV is independent of ISO when specified at ISO 100
- Light meters often display results in EV
- Exposure compensation is measured in EV stops (+1 EV = double exposure)
Exposure Value Formula
EV = log₂(N² / t)
Where:
- EV= Exposure Value
- N= f-number (aperture)
- t= Shutter speed in seconds
- log₂= Base-2 logarithm
Sunny 16 Rule and Light Estimation
The Sunny 16 rule is a classic method for estimating correct exposure without a light meter. On a sunny day, set aperture to f/16 and shutter speed to the reciprocal of ISO (e.g., ISO 100 = 1/100s shutter).
| Lighting Condition | Aperture | Example (ISO 100) | Description |
|---|---|---|---|
| Sunny (hard shadows) | f/16 | f/16, 1/100s | Bright sun, distinct shadows |
| Slight overcast | f/11 | f/11, 1/100s | Soft shadows visible |
| Overcast | f/8 | f/8, 1/100s | No shadows, even light |
| Heavy overcast | f/5.6 | f/5.6, 1/100s | Dark clouds, dim light |
| Open shade | f/4 | f/4, 1/100s | Subject in shade on sunny day |
| Snow or sand (sunny) | f/22 | f/22, 1/100s | Highly reflective surface |
| ISO Setting | Shutter Speed (Sunny 16) | Best Use Case |
|---|---|---|
| 100 | 1/100s or 1/125s | Bright daylight, lowest noise |
| 200 | 1/200s or 1/250s | Daylight, slightly faster shutter |
| 400 | 1/400s or 1/500s | Cloudy days, action |
| 800 | 1/800s or 1/1000s | Indoor/outdoor mixed |
| 1600 | 1/1600s or 1/2000s | Indoor, sports |
The Sunny 16 rule works well as a starting point; fine-tune based on your camera's meter or histogram.
Sunny 16 Rule
Shutter Speed = 1/ISO (at f/16 in direct sunlight)
Where:
- Shutter Speed= Reciprocal of ISO value
- f/16= Fixed aperture for sunny conditions
- ISO= Film or sensor sensitivity setting
Stops and Equivalent Exposures
A stop represents a doubling or halving of light. Understanding stops allows you to maintain equivalent exposure while changing settings for creative effect.
| Aperture (f-stops) | Shutter Speeds | ISO Values | Light Change |
|---|---|---|---|
| f/1.4 | 1/8000s | 25600 | +6 stops from base |
| f/2 | 1/4000s | 12800 | +5 stops |
| f/2.8 | 1/2000s | 6400 | +4 stops |
| f/4 | 1/1000s | 3200 | +3 stops |
| f/5.6 | 1/500s | 1600 | +2 stops |
| f/8 | 1/250s | 800 | +1 stop |
| f/11 | 1/125s | 400 | Base (reference) |
| f/16 | 1/60s | 200 | -1 stop |
| f/22 | 1/30s | 100 | -2 stops |
| Original Settings | Equivalent 1 | Equivalent 2 | Equivalent 3 |
|---|---|---|---|
| f/8, 1/125s, ISO 100 | f/5.6, 1/250s, ISO 100 | f/8, 1/250s, ISO 200 | f/11, 1/125s, ISO 200 |
| f/2.8, 1/500s, ISO 400 | f/4, 1/250s, ISO 400 | f/2.8, 1/1000s, ISO 800 | f/2, 1/1000s, ISO 400 |
All equivalent exposures produce the same brightness but with different depth of field, motion blur, and noise characteristics.
Stop Calculation
Stops = log₂(Value₂ / Value₁)
Where:
- Stops= Number of exposure stops difference
- Value₂= New setting value
- Value₁= Original setting value
Reciprocal Rule for Handheld Shooting
The reciprocal rule helps determine the minimum shutter speed for sharp handheld photos. Your shutter speed should be at least 1/(focal length) to avoid camera shake blur.
| Focal Length | Min Shutter (Full Frame) | Min Shutter (APS-C, 1.5x) | Min Shutter (MFT, 2x) |
|---|---|---|---|
| 24mm | 1/24s → 1/30s | 1/36s → 1/50s | 1/48s → 1/60s |
| 35mm | 1/35s → 1/40s | 1/52s → 1/60s | 1/70s → 1/80s |
| 50mm | 1/50s → 1/60s | 1/75s → 1/80s | 1/100s |
| 85mm | 1/85s → 1/100s | 1/125s → 1/160s | 1/160s → 1/200s |
| 135mm | 1/135s → 1/160s | 1/200s → 1/250s | 1/250s → 1/320s |
| 200mm | 1/200s → 1/250s | 1/300s → 1/320s | 1/400s |
| 400mm | 1/400s → 1/500s | 1/600s → 1/640s | 1/800s |
- Image stabilization (IS/VR/OIS) can add 2-5 stops of handheld capability
- Steady technique and bracing can improve by 1-2 stops
- Higher resolution sensors may require faster shutters
- For moving subjects, faster shutters are needed regardless of lens
Reciprocal Rule
Min Shutter Speed = 1 / (Focal Length × Crop Factor)
Where:
- Min Shutter Speed= Slowest safe handheld shutter speed
- Focal Length= Lens focal length in mm
- Crop Factor= Sensor crop factor (1.0 for full frame)
Metering Modes and Exposure Compensation
Metering modes determine how your camera measures light to calculate exposure. Understanding when to use each mode and when to apply exposure compensation is key to consistent results.
| Metering Mode | How It Works | Best For | Limitations |
|---|---|---|---|
| Matrix/Evaluative | Analyzes entire scene, uses algorithms | General photography, most situations | Can be fooled by unusual lighting |
| Center-Weighted | Emphasizes center 60-80% of frame | Portraits, centered subjects | Off-center subjects may expose incorrectly |
| Spot | Measures only 1-5% of frame | High contrast scenes, backlit subjects | Must meter from mid-tone area |
| Partial | Measures 6-10% of center | Backlit subjects, stage lighting | Similar to spot but less precise |
| Highlight-Weighted | Prioritizes highlight preservation | Concerts, spotlit performers | May underexpose shadows |
| Situation | Exposure Compensation | Reason |
|---|---|---|
| Snow, white sand, bright scenes | +1 to +2 EV | Camera will underexpose to gray |
| Dark subjects, night scenes | -1 to -2 EV | Camera will overexpose to gray |
| Backlit subjects | +1 to +2 EV | Subject is shadowed |
| Spotlight on dark stage | -1 to -2 EV | Preserve performer's exposure |
| High-key portraits | +0.5 to +1 EV | Keep skin tones bright |
The camera's meter tries to make everything middle gray (18% gray). Adjust exposure compensation when your subject is significantly lighter or darker than average.
Exposure Compensation
Final Exposure = Metered Exposure + Compensation
Where:
- Final Exposure= Adjusted exposure settings
- Metered Exposure= Camera's calculated exposure
- Compensation= Manual adjustment in EV stops
Worked Examples
Sunny Day Portrait with Background Blur
Problem:
You want to photograph a portrait on a sunny day with a blurred background using a 50mm f/1.8 lens at ISO 100. What settings would work?
Solution Steps:
- 1Start with Sunny 16 rule: f/16, 1/100s, ISO 100
- 2For background blur, open aperture to f/2.8 (5 stops more light)
- 3Compensate shutter speed: increase by 5 stops
- 41/100s → 1/200s → 1/400s → 1/800s → 1/1600s → 1/3200s
- 5Final settings: f/2.8, 1/3200s, ISO 100
Result:
f/2.8, 1/3200s, ISO 100 gives proper exposure with creamy background blur
Low Light Indoor Event Photography
Problem:
You're shooting an indoor event with available light. The room is dim (EV 6) and you need at least 1/125s to freeze motion. You have an f/2.8 lens. What ISO do you need?
Solution Steps:
- 1At EV 6, reference setting: f/4, 1/15s, ISO 100
- 2Open aperture f/4 → f/2.8: gain 1 stop
- 3Increase shutter 1/15s → 1/125s: lose 3 stops
- 4Net change: -2 stops (need 2 more stops of light)
- 5Increase ISO by 2 stops: ISO 100 → 200 → 400
- 6For 1/125s: ISO 400 should work
Result:
f/2.8, 1/125s, ISO 400 (or ISO 800 for safety margin)
Sunset Landscape with Maximum Sharpness
Problem:
You're shooting a landscape at sunset (EV 11) using a tripod. You want maximum depth of field at f/11 and lowest ISO. What shutter speed is needed?
Solution Steps:
- 1At EV 11, reference: f/8, 1/250s, ISO 100
- 2For f/11 (1 stop smaller aperture): lose 1 stop of light
- 3To compensate, slow shutter by 1 stop: 1/250s → 1/125s
- 4On tripod, any shutter speed is usable
- 5Final settings: f/11, 1/125s, ISO 100
Result:
f/11, 1/125s, ISO 100 for sharp landscape with maximum depth of field
Tips & Best Practices
- ✓Learn the Sunny 16 rule as a backup when your meter fails or batteries die—it's surprisingly accurate
- ✓Each doubling of ISO adds approximately 1 stop of exposure, allowing faster shutter speeds in low light
- ✓Use the histogram, not the LCD preview, to judge exposure—LCDs can be misleading, especially outdoors
- ✓Aperture priority mode with exposure compensation gives you creative control with fast adaptation to changing light
- ✓When in doubt, slightly underexpose digital photos—it's easier to recover shadow detail than blown highlights
- ✓Learn your camera's base ISO (usually 100 or 200)—this gives the cleanest images and most dynamic range
- ✓For critical work, bracket exposures (±1 or ±2 EV) to ensure you capture the best exposure, especially for HDR
Frequently Asked Questions
The f-stop (aperture) is the ratio of the lens focal length to the diameter of the aperture opening. Lower f-numbers (f/1.4, f/2) let in more light with each stop doubling the light. Higher f-numbers (f/11, f/16) let in less light. Each full stop (f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16) either doubles or halves the light compared to the adjacent stop. Aperture also affects depth of field—wider apertures create shallower depth of field.
Use manual exposure when: lighting is consistent and you want repeatable results (studio, events), when camera metering is likely to be fooled (backlit subjects, snow, concerts), or for specific creative effects. Use automatic modes (aperture priority, shutter priority) when lighting changes rapidly (walking between indoor/outdoor), for casual shooting where speed is important, or when learning while still wanting creative control over one variable. Most professionals use aperture priority with exposure compensation for efficiency.
Follow the reciprocal rule: use a shutter speed of 1/(focal length × crop factor) or faster. For a 50mm lens on full frame, use at least 1/50s; on APS-C (1.5x crop), use 1/80s. Image stabilization adds 2-5 stops of capability, so a stabilized 50mm on full frame might be usable at 1/8s. For moving subjects, you'll need faster shutters regardless—1/250s for walking people, 1/500s for jogging, 1/1000s+ for sports. If you need slower shutters, increase ISO or use a wider aperture.
ISO invariance means a camera produces similar image quality whether you raise ISO in-camera or boost exposure in post-processing. ISO invariant cameras allow you to shoot at lower ISOs and recover shadows later without noise penalty. Most modern mirrorless cameras (Sony, Nikon Z, Fuji) are relatively ISO invariant above their base ISO. This is useful when you want to protect highlights—expose for highlights and lift shadows in editing. Test your camera by comparing ISO 3200 shot vs ISO 100 pushed +5 stops in post.
Consistent exposure errors usually have fixable causes: 1) Check exposure compensation—it may be accidentally set. 2) Your camera's meter aims for 18% gray; bright scenes (snow, beach) need +1-2 EV, dark scenes need -1-2 EV. 3) Your metering mode may not suit the scene—try spot metering for tricky lighting. 4) LCD brightness can deceive you—trust the histogram. 5) Some cameras have metering biases—learn your camera's tendencies. Consider shooting RAW for more latitude in post-processing.
The histogram shows the distribution of tones in your image from blacks (left) to whites (right). For proper exposure: avoid clipping (spikes touching either edge), though small clipping may be acceptable. For most scenes, the histogram should span most of the range without crushing blacks or blowing highlights. For dark scenes (night), expect data weighted left. For bright scenes (snow), expect data weighted right. 'Expose to the right' (ETTR) maximizes data quality by pushing exposure just before highlight clipping, then adjusting in post.
Sources & References
Last updated: 2026-01-22