Exposure Lab · by PHOTOWORKS

Exposure Labby PHOTOWORKS

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Exposure Labby PHOTOWORKS

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Exposure Labby PHOTOWORKS

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Exposure Lab

Every photo is one thing:
light.

Three dials decide how much reaches the frame.

Dial 1 · Aperture

The opening.

Open it wide: more light, and the background falls away soft.

Dial 2 · Shutter

The time.

Hold it open longer: more light, and motion draws a streak.

Dial 3 · ISO

The gain.

Turn it up for dark scenes: brighter, but grain moves in.

Balance the three

Meter to zero,
then break it on purpose.

You are ready. Let’s open the lab.

Plan view looking down on the scene, metres across

Blur on the sensor circle of confusion against distance

Numbers

Focal length

The distance from the lens to where parallel light comes together. Longer lens, bigger subject. It gathers no more light: an f-number is a ratio, f / aperture diameter, so f/4 on a 24mm and f/4 on a 400mm meter the same.

Focus distance

Only one plane is ever truly sharp. To focus closer the lens moves out by v = f·D / (D − f), and at infinity v = f. Double the distance, get roughly four times the depth. That is why landscapes hold and macro does not.

Hyperfocal distance

H = f² / (N · c) + f. Focus there and everything from H/2 to infinity reads sharp, the deepest a lens can go at that aperture. Focus past H and you throw away the near half for nothing.

Try this

Turn on hold the framing and run the focal length from 24 to 200. The subject stays the same size and depth barely moves, because focal length was never controlling it. Distance was. Turn it off and repeat: depth collapses.

Lens

Focal length85mm

Aperturef/4

Sets how fast blur grows either side of the focus plane.

FormatFull frame

Camera position

Focus distance3.00 m

Or drag the focus line in the plan view.

Hold the framingOff

Shortcuts

Reading the diagram

The green band is everything that reads sharp. The bright line is the focus plane. The dashed amber line is the hyperfocal distance. The wedge is what the lens actually covers. Below, the curve is the blur diameter landing on the sensor, and the flat line across it is the largest blur a print will still call a point.

Back to a photograph

On the exposure pages every scene is a real photograph, so it holds one lens and one focus plane and the iris is the only thing that moves blur. This page is where those two facts come apart.

Focal length & focus. Every number on this page comes from the thin lens. Image distance is v = f·D/(D−f), hyperfocal is H = f²/(N·c) + f, and the near and far limits follow from H and the focus distance. The acceptable circle of confusion scales with the format, because a smaller frame is enlarged more to reach the same print. © 2026 PHOTOWORKS · Sudeep Mehta. All rights reserved.

Learn exposure.
Without a camera.

Enter your product key

A few details first

Every photo is one thing:
light.

The opening.

The time.

The gain.

Meter to zero,
then break it on purpose.

Match-needle meter TTL

Histogram live

Depth of field metres

Plan view looking down on the scene, metres across

Blur on the sensor circle of confusion against distance

Numbers

Focal length

Focus distance

Hyperfocal distance

Try this

Learn exposure.Without a camera.

Match-needle meter TTL

Histogram live

Depth of field metres

Plan view looking down on the scene, metres across

Blur on the sensor circle of confusion against distance

Numbers

Focal length

Focus distance

Hyperfocal distance

Try this

Learn exposure.
Without a camera.