Crop factor

Definition

Crop factor compares your sensor diagonal to a 36×24 mm frame (diagonal ≈ 43.3 mm). APS-C is typically 1.5× or 1.6×, Micro Four Thirds 2×, many 1-inch compacts ~2.7×. A 50 mm on APS-C frames like a 75 mm on full frame. Depth of field and equivalent aperture also shift with crop if you match field of view and f-number. Crop factor does not magically add reach — it only describes the smaller window on the same optic.

Calculators that use this

• Sensor & focal length

  Crop Factor Calculator

  Get sensor diagonal, crop factor versus 36×24 mm full frame, and 35 mm-equivalent focal length from your sensor size and lens.

• Sensor & focal length

  Equivalent Aperture Calculator

  Convert an f-number through crop factor into a full-frame-equivalent aperture and the DoF stop delta. Exposure on the sensor stays the f-number you set.

• Astrophotography

  500 Rule Calculator

  Estimate the longest untracked shutter for stars with the 500, 300 and 200 rules from focal length and crop factor.