In addition to providing a larger display, many camera monitors provide additional tools to assist camera operators. Such tools include framing guides, focus peaking, zebra stripes, waveform monitors (oftentimes as an "RGB parade"), vectorscopes and false color to highlight areas of the image critical to the operator. Most typically provide the ability to apply a LUT to the video in real-time allowing filmmakers to view their footage with their color grading already applied.4
Some camera monitors also offer a recording function. These recorders typically encode footage in a higher quality (using CODECs such as Apple ProRes or Avid Technology's DNxHR codec) and to larger storage mediums than many consumer cameras provide internally. Additionally, many cameras output higher quality video (with less or no chroma subsampling and potentially a higher color depth) through their external connections than they can record internally. For example, some cameras output 10-bit color with 4:2:2 chroma subsampling through their HDMI connections, while only recording 8-bit color with 4:2:0 chroma subsampling internally.
Recorder monitors are also used in conjunction with PTZ cameras to allow recording and editing on the fly. This has the twin benefit of avoiding the PTZ camera getting too hot as well as allowing editing to take place in real time with the use of LUTs etc, thus saving time and money.
Butler, Richard; Baskin, Dale. "Why would I want an external recorder/monitor?". Digital Photography Review. Archived from the original on 2019-07-21. Retrieved 2019-07-20. https://www.dpreview.com/articles/3388025881/why-would-i-want-an-external-recorder-monitor ↩
"Atomos releases new 'Flame' versions of Shogun and Ninja recorders". Digital Photography Review. Archived from the original on 2019-07-21. Retrieved 2019-07-21. https://www.dpreview.com/news/0152139543/atomos-releases-new-flame-versions-of-shogun-and-ninja-recorders ↩