describes exactly how many frames per second a video recorder can actually capture. Analog recorders like VCRs can easily record in real time (30 frames / sec. for standard NTSC) or time lapse (fewer than 30 frames/sec. for NTSC). Many digital DVR recorders, however, cannot record actual real time video. For most situations, recording rate is the spec to pay attention to. (Specifications for digital video equipment are not the only numbers to rely on. In fact, many DVR recorders outperform their specifications upon real world testing while other low quality units often record at a much slower rate than their specs claim).

describes the number of full video frames displayed or recorded within one second. True real time video consists of 30 frames/sec. for NTSC format and 25 frames/sec. for PAL format. Be sure not to confuse frames per second with "fields per second" or "images per second". A complete frame of video is compiled of two separate images (or fields), so the number of fields in one second is always twice the number of frames per second.