Depth of Field Calculator
景深计算器
Format-aware DOF calculations for 35mm and medium format film
Depth of field – the range of distances in a photograph that appear acceptably sharp – is one of the most critical creative controls in film photography. Unlike digital cameras that offer instant review, film photographers must visualize their depth of field before pressing the shutter. FilmMeter’s depth of field calculator provides real-time DOF information based on your actual shooting parameters, helping you make confident focus decisions whether you are shooting wide-open portraits on Portra 400 or stopped-down landscapes on Velvia 50.
Format-Specific Circle of Confusion
The foundation of any accurate DOF calculation is the circle of confusion (CoC), which defines the maximum acceptable blur circle diameter for a point of light. Different film formats require different CoC values because larger negatives are enlarged less for a given print size. FilmMeter uses format-specific values:
- 35mm (135 format): 0.029mm circle of confusion – the standard for full-frame photography
- 120 medium format: Larger CoC values calculated per sub-format (6x4.5, 6x6, 6x7, 6x9), reflecting the reduced enlargement ratio of medium format negatives
This means the same lens focal length, aperture, and focus distance will produce different depth of field results depending on whether you are shooting medium format or 35mm – and FilmMeter handles this automatically when you select your film format.
Hyperfocal Distance
The hyperfocal distance is the focus point at which depth of field extends from half the hyperfocal distance to infinity – maximizing sharpness throughout the scene. FilmMeter calculates this value in real time for your current aperture and focal length combination, making it invaluable for street photography and landscape work. Focus at the hyperfocal distance with your 35mm f/2 lens stopped down to f/8, and everything from roughly 3 meters to infinity will be acceptably sharp on 35mm film.
Visual DOF Scale
Inspired by the depth of field markings engraved on classic Leica, Nikon, and Zeiss lenses, FilmMeter displays a visual DOF scale that shows your near focus limit, far focus limit, and total depth of field range. As you adjust aperture or focus distance – either manually or via LiDAR measurement – the scale updates instantly, giving you the same information as a physical lens barrel but with greater precision and real-time feedback.
Practical Applications
Combine the DOF calculator with precision metering to make informed exposure trade-offs. Need more depth of field for a group portrait? Stop down two stops and let FilmMeter recalculate your shutter speed. Shooting a medium format Hasselblad and wondering how much shallower your 80mm f/2.8 will render compared to the 35mm equivalent? The calculator shows you instantly. Record your chosen settings in the film roll management system for future reference.