If CRT (cathode ray tube) computer or TV screens are recorded on film, the scan lines on the picture tubes can become visible, making a mess of the image that was easy to see by everyone but the camera. This is because the TV's scan rate and camera's frames-per-second are not synchronized, and as a result, a black bar repeatedly rolls up or down the screen.
There are two ways to avoid this. First, there are ways a television screen can be specially synced up with the camera. This is surprisingly difficult with older technology. Indeed, nobody completely figured this out until 1982's Videodrome, although a few productions managed it with black and white monitors.
Second, the images on the TV/computer screen can instead be added as an optical effect in post-production, with the result that now a clear picture appears. This is a less sophisticated effect, so you tend to see it more often only in older productions. Sometimes, the FX-inserted image is suspiciously crisper than everything else around it. Another dead giveaway is the shot suddenly moving to an extreme closeup of the TV screen, with only a dial, button, or paying brand name visible off to one side to even clue the viewer in that they're being shown the same screen that other characters are looking at, and not switching scenes entirely.
Rarely seen on newer shows because of advances in special effects and new monitor technology, but just about any sci-fi series from The '60s or The '70s will have at least one example.
Compare If You Can Read This, when the words on an on-screen printed page are readable by the viewers (often post-CRT only) and can contain extra information. Compare and contrast Super Cell Reception, when it's cellphone signal reception that comes unbelievably clear in unlikely places. Contrast Deliberate VHS Quality, the usage of VHS quality —despite digital formats being available— to achieve certain aesthetics, and Raster Vision, the deliberate usage of analog TV scan lines. Sub-Trope of In-Camera Effects.
Examples:
Films — Live-Action
- Dawn of the Dead (1978): Used for every TV picture, although genuine static appears at the end, after transmissions have stopped coming.
- Broadcast Signal Intrusion: One scene has James using a projector to blow up pictures of the pirate broadcast, it has film-like resolution, despite being on a Betamax tape.
- The Three Stooges In Orbit: Near the end, television executives are watching a demo reel of a new style of Stooges cartoon on television, when the building gets crashed into. The TV is knocked around like the other props, but the image doesn't and keeps running even after one would think the set lost power. This, by the way, was not done in a closeup of the screen.
- Total Recall (1990): The visuals on the large TV screen in Quaid's living room are superimposed on the actual film. It's almost unnoticeable though.
- Videodrome: Being a movie about media theory and the televisual medium, apparently put a lot of work into solving this issue, and is in fact the first movie to properly sync up colour monitors with the cameras.
Live-Action TV
- Adam Ruins Everything:
- In the Election Special, Adam shows his "campaign ad" while making the point that the Electoral College makes politicians focus on states with narrow margins. It is on a CRT TV from The '90s, but the quality is HD.
- In "Adam Ruins Sex", the ruinee shows a VHS tape he made in The '90s about how herpes is horrible to have, but the quality is HDnote . Adam promptly inserts himself into the tape and informs them that unless you're immunocompromised, herpes is no big deal.
- Gerry Anderson: Averted in both UFO (1970) and Space: 1999, where most of the video monitors (even hand-held ones) are real, though the images are in black and white because the production hadn't yet figured out how to synchronize colour monitors to 35mm film cameras. However, the main Moonbase Alpha viewscreen on Space: 1999 uses matted-in images, which are therefore in colour.
- Doctor Who: In "The Sea Devils", the Master watches an episode of The Clangers on television. The image is inserted using a yellow Chroma Keynote in the form of miniblinds. As a result, the display is very clean.
- Gemini Man: The monitor Abby uses to keep tabs on Casey in the second half of Riding with Death has a better resolution than the rest of the two-parter.
- The Goodies: It makes heavy use of this. Though considering the 'TV' was 'actually' a super advanced projector thingy, which suspiciously worked exactly like a set of blinds, it was probably a tad less serious.
- Monarch of the Glen: At the beginning of the second series, a camera system is set up around the estate, and the resolution on the screens is amazing (TV broadcast quality), even for the year 1999.
- Mystery Science Theater 3000:
- In one of the Master Ninja movies, the villains watching a surveillance screen that looks suspiciously sharper than the rest of the scene. A similar effect appears in the Riding With Death movie. Both movies are made somewhere in The '70s to early 80s.
- The host segments feature the "Hexfield Viewscreen", a video-phone device that was basically a fancy opening into another room, where actors would stand and converse with the cast. The artifice of this fake screen was further highlighted in an episode where the "image" breaks up with "static" —visibly a scatter of little styrofoam pellets being thrown at the actor from offstage.
- In one episode, the static is produced by styrofoam pellets being thrown around.
- Spynet: Not only were the villains' computers CRT monitors with visible scanlines, they didn't even have a Viewer-Friendly Interface... just Windows 95.
- The Young Ones: One episode doesn't even bother with a green screen —there's simply a static image taped to the front of the television, and the actors and camera positioned themselves so that the TV was only visible while it was "on".
Western Animation
- Roughnecks: Starship Troopers Chronicles: The rolling bar is added deliberately to a background monitor to add 'realism' to a scene.
