Calculators
Photo calculators
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Reti is free and ad-free We build Reti after hours, out of love for photography. If one of the tools helped you, you can buy us a coffee. Buy us a coffee on Ko-fi →Depth of field
Preview: focus is on the person, the posts show distance
Calculated for a circle of confusion of diagonal/1500. It is an approximation for a photo viewed as a whole. The scene is drawn: we calculate the blur of each plane with the same formulas.
Equivalent focal length
Preview: the same lens on two sensors
An f/2.8 aperture gives the same exposure on every sensor, so shutter speed and ISO stay the same. Only depth of field changes: on a smaller sensor with the same framing it is deeper, as on full frame at a smaller aperture.
ND filter: new shutter speed
Preview: water and clouds at both speeds
Stars without trails
Preview: 100% crop (150 sensor pixels), a star near the celestial equator, i.e. the longest trail
The 500 rule is simple but gives slight trails with today's sensors. The (simplified) NPF rule takes resolution and aperture into account, so it is more accurate.