📷 Focal Length & Crop Factor Calculator
Find the full-frame equivalent focal length and field of view for any sensor and lens combination.
| Focal Length (FF equiv.) | Category | Typical Use |
|---|---|---|
| 10–18mm | Ultra-Wide | Architecture, interiors, dramatic landscapes |
| 18–35mm | Wide | Street, landscape, environmental portraits |
| 35–55mm | Standard | Documentary, walk-around, natural perspective |
| 55–105mm | Portrait | Flattering portraits, product, moderate compression |
| 105–300mm | Telephoto | Wildlife, sports, compressed backgrounds |
| 300mm+ | Super Telephoto | Birds in flight, distant sports, astronomy |
Crop Factor & Equivalent Focal Length
A crop factor (also called focal length multiplier) describes how a sensor's size compares to a full-frame (35mm) sensor. A smaller sensor captures a smaller portion of the image projected by the lens, effectively "cropping in."
To find the full-frame equivalent focal length, multiply your actual focal length by the crop factor. A 35mm lens on an APS-C camera (1.5×) behaves like a 52.5mm lens on a full-frame camera in terms of field of view.
Field of View (FOV) is calculated from the equivalent focal length and the 35mm sensor dimensions (36mm wide × 24mm tall). The formula is: FOV = 2 × arctan(sensor_dimension / (2 × focal_length)). Diagonal FOV uses the full diagonal (43.3mm).
Note: crop factor affects field of view only, not depth of field (DOF is determined by the physical aperture, not equivalent focal length). For DOF, use the actual focal length with the physical sensor size.