Work it out.
Calculators
Exposure value (EV)
Fototeknik · EV-formel (APEX)
Equivalent shutter speed
Fototeknik · Reciprocitet (EV konstant)
Print resolution (PPI)
Digital billedbehandling · PPI = pixels / tommer
Hyperfocal distance
Optik — hyperfokal-formel (Zeiss-formlen, H. H. Nasse)
Near and far limits of depth of field
Optik — DOF-formel (samme grundlag som hyperfokalafstand)
Size of the field of view at the subject
Geometri — ligedannede trekanter (tyndlinse-tilnærmelse)
Crop factor and equivalent focal length
Geometri — sensordiagonal (Pythagoras), fuldformat-reference 36×24 mm
Guide number and flash range
Fotoflash-fysik — ledetal (GN = afstand × blænde ved ISO 100)
Flash output in stops
Fotoflash-fysik — effekttrin i stop (log₂ af effektbrøken)
Inverse square law — light falloff with distance
Fysik — omvendt kvadratlov (I ∝ 1/afstand²)
Memory card capacity
Forholdsregning — filstørrelse × kortkapacitet
Diffraction limit at small apertures
Optisk fysik — Rayleigh-kriteriet / Airy-disk (d = 2,44 · λ · f-tal)
Max. exposure time without star trails (500 rule)
Astrofoto-tommelfingerregel (500-reglen)
Number of images for a panorama
Geometri — vinkeldækning og overlap (branchevejledning 20-30 %)
Time-lapse interval
Forholdsregning — optagevarighed, billedantal og fps
180° shutter rule for video
Filmkonvention — 180°-lukkervinkel (t = 1 / (2 × fps))
Tools that work in all subjects
Whatever your programme is called, these tools calculate the same — Pythagoras, area, percentages and units are not tied to one trade.
- Pythagorasa² + b² = c²Find the missing side, set out a right angle, check whether a room is square, and find the space diagonal.
- Area and perimeterm²Rectangle, triangle, trapezium, circle and composite shapes — area and perimeter.
- Volume and surface aream³ · lBox, cylinder, cone, sphere, pyramid, prism, pipe and frustum — also in litres.
- Percent%Percentage of, how many per cent, percentage change, discount and VAT.
- Scale and ratios1 : 50From drawing to reality, area and volume to scale, the rule of three and dividing in a ratio.
- Unit convertermm ↔ mFrom mm to km, Pa to bar and kB to GB — with the unit staircase.
- Time calculations and the clockt : minTime between two clock times, add time, and 1.75 h = 1 h 45 min for the timesheet.
- Slope and fall% · ° · 1:xFall from level to level, in per cent, per mille, degrees and mm per metre — and the height difference.
- Material consumption including wastem² + %Boards, paint, battens at c/c spacing and packs — for a composite surface or a whole room, with waste.