"Full frame" refers to the sensor size being the same (approximately) as a 35mm film frame, or 24mm x 36mm. "Crop Sensor" cameras have a sensor that is smaller than 24mmx36mm. Your 400D has a sensor 14.8mmx22.2mm, and is often called "APS-C", in reference to a similar frame size available with the (nearly, if not A smartphone sensor thus has a diagonal 6× smaller than for full-frame DSLRs, and a surface area roughly 36× smaller (“roughly” because they can have different ratios of sides). Meanwhile in medium-format and larger cameras, the sensors are larger than full-frame and thus have a crop factor of less than 1 (typically from 0.5 to 0.8). 4K video is average. The EOS R5 is a powerhouse full frame mirrorless camera that will satisfy any professional photographer or videographer. It's a jack-of-all-trades camera, excelling in various segments and earning spots in categories like best for resolution, best for video, best for sports, and practically best at everything. 1/2.3″ This is the standard image sensor size in GoPro cameras. 1/1.9″ New image size in Hero11 Black and Black Mini. 1/1.7″. 2/3″. CX (Nikon) APS-C. 35 mm (Full frame) This is the standard sensor size that all others are compared against. The crop factor (see above) is used to compare other sensors against this size. Omni's crop factor calculator will let you know what your camera and lens combination looks like in terms of a 35mm full-frame sensor size camera. It calculates both the 35mm equivalent focal length and aperture f-stop value (or f-number). This allows you to see how your image magnification and depth of field compares to a standard 35mm camera. It is determined as the ratio of diagonals of the two sensors. A crop sensor is exactly a crop from a larger sensor. Put a full-frame camera beside a 1.6 crop camera and if the full-frame camera has a lens with a focal length 1.6 times larger than the lens of a crop camera, the photos taken by both cameras will be identical by the viewing angle. For example, a 50mm lens on a full frame sensor will have a field of view of 50mm — whereas this same lens on a crop sensor camera will have a field of view of 50mm x 1.5 or 1.6 (the crop factor) which leads your 50mm lens to feel a bit more telephoto than it otherwise would — more like a 75mm lens. Image from a 1.3x sensor camera (Canon 1D series). Image from a 1.5x sensor camera (Nikon DX digital). Image from a 1.6x sensor camera (Canon consumer digital SLRs). Calculations. Multiply a lens' focal length by a camera's factor to get the focal length of a lens which, when used on a full-frame or 35mm film camera, gives the same angle of .