Free Tool

Exposure Triangle Calculator

Name: Exposure Triangle Calculator
Author: Infinite Creation

Pick your lighting, frame rate, and aperture. The calculator finds the correct ISO, and tells you when you need an ND filter.

1, Scene Lighting

2, Frame Rate

Shutter speed (180° rule): 1/50s

3, Aperture

f/1.4 (shallow DoF) f/16 (deep DoF)

f/2.8 Shallow DoF

ISO

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Aperture

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Shutter Speed

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180° rule

How the Exposure Triangle Works

ISO, Sensor Sensitivity

Amplifies the signal. Low ISO (100 to 400) produces a clean image. High ISO (3200+) introduces grain and noise. Raise it only when aperture and shutter are already at their limits.

Aperture, Lens Opening

Controls depth of field and light intake. Wide apertures (f/1.4, f/2.8) blur the background and let in lots of light. Narrow apertures (f/8, f/16) keep everything sharp but admit less light.

Shutter Speed, The 180° Rule

For video, shutter speed is locked to 2× your frame rate. This creates natural motion blur. Changing shutter speed to fix exposure breaks the look of your footage. Use ISO or aperture instead.

ND Filters, The Override

Neutral density filters reduce light without affecting colour or depth of field. Essential for shooting wide apertures outdoors. Variable NDs cover 2 to 8 stops. Fixed NDs (ND4, ND8, ND64) are more consistent.

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Knowledge Base

How to Use the Exposure Triangle Calculator

The Exposure Triangle Calculator shows the relationship between aperture (f-stop), shutter speed, and ISO. Adjust one and see how the others change to maintain proper exposure. Understanding these three elements is fundamental to photography and cinematography.

The Three Pillars of Exposure

Aperture (f-stop): Controls how wide the lens opens. f/1.4 is wide (bright), f/16 is narrow (dark). Also affects depth of field.
Shutter Speed: How long the sensor is exposed. 1/1000 is fast (freezes motion), 1 second is slow (motion blur).
ISO: Sensor sensitivity. ISO 100 is low (clean), ISO 6400 is high (noisy). Use lowest ISO possible for cleaner image.

Practical Trade-Offs

Increasing light: Open aperture wider, slow shutter, or raise ISO. But: wider aperture reduces DOF, slower shutter risks blur, higher ISO adds noise.
Decreasing light: Close aperture, speed up shutter, or lower ISO. But: narrower aperture increases DOF, faster shutter freezes motion (good for action), lower ISO is clean but needs more light.

Video vs. Photography

In video, shutter speed is locked to your frame rate (24fps = 1/48s, 30fps = 1/60s). You control exposure primarily with aperture and ISO. In photography, you have full control of all three.

FAQ

Q: Should I prioritize aperture or shutter speed?
A: Depends on your creative goal. Want background blur? Prioritize wide aperture. Want motion control? Prioritize shutter speed.

Q: How much ISO noise is acceptable?
A: For cinematic work, stay below ISO 3200. Documentary/news work tolerates ISO 6400+.

Trading the three controls

Aperture, shutter and sensitivity each change exposure, and each costs something else. Aperture changes depth of field, shutter changes motion blur, and sensitivity changes noise. Because any of the three can compensate for either of the others, exposure is never one correct answer but a choice about which side effect you want.

Video removes most of the shutter freedom that stills photography has. Motion blur has to look consistent, so shutter is conventionally locked at roughly double the frame rate, giving the 180 degree shutter. That leaves aperture and sensitivity doing the work, and it is why neutral density filters are standard on a video set and rare in stills.

Aperture is usually chosen for the look rather than for the exposure. How much of the frame stays sharp is a storytelling decision, so the aperture gets set for that and the other controls adjust around it. Changing aperture to fix brightness quietly changes the depth of field that was chosen deliberately.

Raise sensitivity last, and know where your camera stops being clean. Every sensor has a range where noise is unobtrusive and a point past which it is not, and that point differs enormously between cameras. Finding yours with a test rather than trusting the specification is fifteen minutes well spent.

Neutral density filters are what make the trade workable outdoors. With shutter locked and aperture chosen for the look, bright daylight leaves nothing to adjust, and reducing light before it reaches the sensor is the only remaining control. This is why filters are ordinary equipment on a video shoot rather than a specialist accessory.

Vocabulary

Aperture. The size of the lens opening, written as an f-number. Smaller numbers mean a wider opening, more light and shallower depth of field. Usually chosen for the look and left alone.

Shutter angle. Shutter speed expressed relative to frame rate, inherited from rotating film shutters. A 180 degree shutter exposes for half of each frame and produces the motion blur audiences read as natural.

ISO. A camera's sensitivity setting. Raising it brightens the image and increases noise, which is why it is conventionally the last of the three controls to move.

Neutral density filter. A filter reducing light without changing colour, letting you keep a chosen aperture and shutter in conditions too bright for them. Standard equipment for video, where shutter is not free to change.