Camera arithmetic: depth of field, field of view, exposure and ND stops, flash, golden hour, astro and time-lapse.
Calculators for the decisions made before the shutter: how much is sharp at this aperture and distance, what a lens takes in on this sensor, how many stops an ND filter or a change of ISO costs, where a flash reaches, when the light turns golden, how long a star exposure can run and how many frames a time-lapse needs. Every page shows its formula; sensor sizes are offered as commonly published presets and your camera’s own figures replace them.
Crop factor from the sensor diagonal, the full-frame equivalent focal length and depth-of-field aperture, and the lens that frames the same on another format.
You get: The crop factor against full frame, the equivalent focal length and the aperture that gives the same depth of field, and the focal length and aperture that match your framing on any other sensor format.
Open Crop Factor & Equivalent Focal LengthNear and far limits of sharp focus, total depth of field and the hyperfocal distance from focal length, aperture, focus distance and sensor, in metres or feet.
You get: Where sharp focus starts and ends, how deep the zone is and how much lies in front of the subject, the hyperfocal distance and its near limit, and the circle of confusion used — which you can change.
Open Depth of Field & Hyperfocal DistanceHorizontal, vertical and diagonal angle of view for a lens and sensor, the scene it covers at a distance, or the focal length for an angle or frame width.
You get: The three angles of view, the width and height of scene covered at your subject distance, the full-frame equivalent — or, working backwards, the focal length that gives the angle or the frame width you want.
Open Field of View & Focal LengthMagnification from extension tubes or a close-up (diopter) lens, the field of view it gives, the working distance, and the light lost as an effective aperture.
You get: The magnification tubes or a close-up lens give on your lens, the subject area that fills the frame, the close-up lens’s working distance, and the effective aperture and stops lost to the extension.
Open Macro Magnification & Extension TubesPixel pitch from the sensor and resolution, the Airy disc at an aperture, and the f-number past which diffraction starts to soften detail at the pixel level.
You get: The pixel pitch and megapixels, the Airy disc diameter at your aperture in microns and pixels, the diffraction-limited aperture by the criterion you choose, and the circle of confusion in pixels for comparison.
Open Pixel Pitch & Diffraction LimitExposure value from aperture, shutter speed and ISO, and the equivalent setting when you change two of the three; shutter as 1/250 or in seconds.
You get: The EV at ISO 100 for the settings you metered, the third setting that keeps the same exposure when you change the other two, and how many stops each control moved.
Open Exposure Value & Equivalent ExposureAperture for a flash distance, or the reach at an aperture, from the guide number at your ISO and power — metres or feet, with the inverse-square falloff.
You get: The aperture a flash at a distance needs, or how far it reaches at an aperture, the effective guide number at your ISO and power, and the distances one stop darker and two stops brighter.
Open Flash Guide NumberMorning and evening golden hour and blue hour for any place and date from the Sun’s elevation — NOAA solar equations, the elevation bands as inputs.
You get: When golden hour and blue hour start and end in the morning and the evening, how long each lasts, solar noon and the Sun’s height at noon — for your latitude, longitude, date and UTC offset.
Open Golden Hour & Blue HourLong-exposure time behind an ND filter from the metered shutter and the filter in stops, factor (ND64) or density, with stacked filters and film reciprocity.
You get: The shutter time with the filter, the filter strength in stops, factor and optical density, the total for stacked filters, and — for film — the time after a reciprocity correction from the datasheet.
Open ND Filter Exposure TimeLongest untracked star exposure before trails show, by the 500 and NPF rules, from lens, aperture, sensor and pixel count, with declination and trail rotation.
You get: The 500-rule (or your constant) and NPF exposure limits, the declination correction for where you aim, the image scale in arcseconds per pixel, and how far the sky turns during a star-trail session.
Open Astrophotography Exposure (500 & NPF Rules)Frames, clip length and speed-up from shooting time, interval and frame rate, or the interval a clip needs, with storage and a shutter-versus-interval check.
You get: How many frames a shoot gives, how long the clip runs and how much faster than real time, the interval for the clip you want, the card space needed, and whether the exposure leaves time between frames.
Open Time-Lapse Calculator