ISO Aperture Shutter Speed Calculator

Example Data Table

Formula Used

Exposure value at ISO 100:

EV100 = log2(N² / t)

N is aperture f-number. t is shutter time in seconds.

Scene exposure value:

Scene EV = EV100 - log2(ISO / 100)

Equivalent shutter speed:

Target t = Base t × (Target N / Base N)² × (Base ISO / Target ISO) × 2^(compensation + ND stops)

Equivalent aperture:

Target N = Base N × square root((Target t × Target ISO) / (Base t × Base ISO × 2^(compensation + ND stops)))

Equivalent ISO:

Target ISO = Base t × (Target N / Base N)² × Base ISO × 2^(compensation + ND stops) / Target t

How to Use This Calculator

1. Enter your current aperture, shutter speed, and ISO.
2. Choose the calculation mode you need.
3. Enter the target aperture, shutter, or ISO values.
4. Add exposure compensation when you want brighter or darker output.
5. Add ND filter stops when using neutral density glass.
6. Press Calculate to view results above the form.
7. Use CSV or PDF buttons to save the calculated report.

ISO, Aperture, and Shutter Speed Guide

Exposure Triangle Basics

Camera exposure is controlled by three connected settings. ISO changes signal gain. Aperture changes lens opening. Shutter speed changes capture time. Each setting affects brightness. Each setting also affects image style. A good exposure keeps detail in bright and dark areas. It also supports the visual goal of the photograph.

Why Stops Matter

Stops give a simple way to compare exposure changes. One stop doubles or halves light. Moving from ISO 100 to ISO 200 adds one stop. Moving from f/4 to f/5.6 removes one stop. Moving from 1/250 second to 1/125 second adds one stop. The calculator converts these linked choices into equivalent settings.

Using Aperture

Aperture is written as an f-number. Smaller f-numbers create a wider opening. Wider openings admit more light. They also reduce depth of field. Portraits often use wider apertures. Landscapes often use smaller apertures. The tool helps you change aperture while preserving exposure.

Using Shutter Speed

Shutter speed controls motion appearance. Fast speeds freeze movement. Slow speeds show blur. Handheld work often needs faster speeds. Tripod work can use longer speeds. When aperture or ISO changes, this calculator finds the matching shutter time. It accepts fractions like 1/125. It also accepts decimals.

Using ISO

ISO raises image brightness after capture. Higher ISO helps in darker scenes. It can also increase visible noise. Lower ISO usually gives cleaner files. This calculator estimates the ISO needed when shutter and aperture are fixed. That is useful for sports, wildlife, concerts, and indoor events.

Neutral Density Filters

Neutral density filters reduce incoming light. They are rated in stops. A three stop filter needs eight times more exposure time. Photographers use them for smooth water, soft clouds, and wider apertures in bright light. Enter ND stops to include that light loss in the result.

Exposure Compensation

Exposure compensation changes the target brightness. Positive values make the result brighter. Negative values make it darker. Snow scenes may need positive correction. Dark stage scenes may need negative correction. Use small changes first. Then compare the result with your camera histogram.

Practical Workflow

Start with a known good exposure. Enter it as the base setting. Pick the setting you want to protect. For action, protect shutter speed. For depth of field, protect aperture. For clean files, protect ISO. Then calculate the remaining value and test it in real light.

FAQs

What does this calculator solve?

It solves equivalent camera exposure settings using ISO, aperture, and shutter speed. It can calculate a target shutter, aperture, or ISO while keeping exposure balanced.

Can I enter shutter speed as a fraction?

Yes. You can enter values like 1/125, 1/60, or 1/1000. You can also enter decimal seconds, such as 0.5 or 2.

What is EV100?

EV100 is exposure value normalized to ISO 100. It compares aperture and shutter combinations without direct ISO gain.

What does one stop mean?

One stop means a doubling or halving of light. It can come from ISO, aperture, shutter speed, exposure compensation, or filter strength.

How do ND stops affect shutter speed?

ND filters reduce light. Each stop doubles the required exposure time when aperture and ISO stay unchanged.

Does higher ISO add more light?

Higher ISO does not physically add more light. It increases signal gain, which makes the image appear brighter but may add noise.

Why is aperture squared in the formula?

Aperture f-number affects lens opening area. Light transmission changes with the square of the f-number ratio.

Can this replace a camera meter?

No. It is a planning tool. Real scenes, metering modes, lens transmission, and creative choices can still require testing.