What is camera frame?
Camera frame indicates the sensor size of the the camera.
36 x 24 mm sensor: full Frame (most expensive)
24 x 16 mm sensor: called APS-C, or DX frame (by Nikon)
The larger the frame is, the wider the camera can capture in a photo.
The relation between frame size and focal length:
focal length and view angle.
Full frame is suitable for shooting landscapes. Here is why.
A 85mm (fixed) lens on a full frame camera, its equivalent focal length is 85mm
A 85mm (fixed) lens on a 24 x 16 mm APS-C (DX)frame, its equivalent focal length is 85mm X 1.6mm = 136mm (85mm X 1.5mm = 127mm
And a 16mm wide angle lens, if on a APS-C (DX)frame, its equivalent focal
length is 26mm (24mm). 16mm lens view angle is 98 degree, while 26mm (24mm) lens view angle 80 degree (84 degree).
To be updated.