This question applies to the legacy Photon camera models. The Photon product line and its accessories have been discontinued. The information here is provided for historical reference.
The legacy Photon generates analog video that complies with NTSC video standards, or PAL video standards if so configured. Each video frame is comprised of two interlaced video fields (odd and even). As in traditional video systems, fields are sampled every 1/60th of a second (1/50th second PAL), one odd and one even. These fields are recombined into a video frame every 1/30th of a second (1/25th second PAL) to conform to NTSC and PAL standards for interlacing and display.
In traditional video systems, each odd and even field is sampled 1/60th of a second apart. For legacy Photon, both odd and even video fields are sampled at the same time. But even though the fields are then interlaced to generate a frame, the data in each legacy Photon video field (odd & even) is identical. Since each odd and even field contains exactly the same data, the legacy Photon`s video display, while fully compliant to NTSC standards, is consistent with a progressive scan mode with the video sampling benefits of more detail and less flicker. The digital output of legacy Photon is exclusively progressive scan.