50i records using the interlace scanning system, and 50p/25p records using the progressive scanning system. 50p records 50 frames per second, while 25p records 25 frames per second. If you set the frame rate to 25p, you can record movies which provide an atmosphere closer to that of film images. 50i is recommended for normal recording.
The interlace scanning system reads even-numbered and odd-numbered scanning lines alternately. Meanwhile, the progressive scanning system reads even-numbered and odd-numbered scanning lines simultaneously thus it has double information per unit time compared with the interlace scanning system (in case of 50p).