A character takes a picture with a camera, and the photo develops, revealing that the photographer had his/her finger(s) on the lens or left the lens cap on, obscuring the subject of the photo. Early cameras used a second lens, directly above the main lens, to provide the viewfinder's view. Since the lens which the photographer is looking through is separate from the lens which will expose the film when the shutter is clicked, it was easy to unknowingly cover the exposing lens. Since most twin-lens cameras were film cameras, the mistake would not be discovered until the film was developed, long after the opportunity to retake the photo had passed. SLR cameras use a mirror and prism to show the exact view through the lens in the viewfinder, making this mistake unlikely. Digital cameras display the image immediately after it's taken, allowing this mistake to be quickly corrected should it happen. See also Body Wipe. Not to be confused with the Camera Obscura. Nor should it be confused with the Camera Obscura, from which this trope derives its name.
- Ambush Bug did this in one of his 1980s miniseries.
- Crocodile Dundee:
Neville Bell: Oh no, you can't take my photograph.Sue Charlton: Oh, I'm sorry, you believe it will take your spirit away.Neville Bell: No, you got lens cap on it.
- Sky Captain and the World of Tomorrow: Polly Perkins spends much of the movie with only two frames left on her only roll of film, and wants to save them for a truly awesome photo. At one point she accidentally shoots the ground while running away, reducing it to one. In the film's denouement, she decides to take a photo of Joe Sullivan, only for Joe to look at her and say "Lenscap."
- Annoyingly, she could still have taken that picture. With the lens cap on, there would have been no light - meaning no exposure. Being that the while movie is 40's retro technology, that was probably a manual camera. If she didn't advance the film, she could have taken the cap off and shot that frame again.
- In Discworld, Rincewind uses a camera flash to defeat an Eldritch Abomination and later finds out that he only has a photo of his thumb to show for it.
- In the original Cheaper by the Dozen book, the father of said dozen children wants the removal of his children's and his own tonsils filmed. Since he wants to direct the filming of his own tonsil removal, he stays conscious during the procedure, and suffers great pain because of this. The pain turned out to be all for naught when the cameraman revels he accidentally left the lens cap on.
- There was an episode of CSI where they started trying to identify the taker of a photograph by the print of the picture of his thumb he left over the lens (until they decided they could get more information by looking in the reflection of the subject's eyes. That episode was worrying on so many levels.)
- MADtv: one part of an Average Asian skit ends with this.
- From Heywood Banks' "Trauma to the Groin":
Too bad we left the lenscap on the camera by mistake/'Cause grandpa weren't too happy about the second take
- There is a running gag in the Curtis comic strips where Curtis' barber claims to have met someone famous. When asked to show proof, he will inevitably produce a photograph of himself with his arm around the celebrity... except that the "celebrity" will be obscured by a finger.
- U.S. Acres: Wade forgot the lens cover on when he tried to take a picture of the Trough Ness Monster.
- That famous picture of George W. Bush looking through the binoculars and they have caps on (which may or may not have been manipulated; undetermined according to Snopes).
- A similar picture exists with Bill Clinton, of course.
- And Amir Peretz, then-Minister of Defence of Israel, has a video.
- The Sims 3 has this occur from low photography skill, making the photos near worthless.
- Disgaea 2 has White Dwarf Star Axel trying to rekindle his fame by fighting Adell and "rescuing" Rozalin, who he believes Adell has kidnapped, and having it filmed by the crew of his poorly rated travel show. Although he loses the fight (badly), the director is sure they can edit the footage into an epic scene...or could if the zombie cameraman hadn't left on the lens cap.
- Wile E Coyote And The Roadrunner: Coyote uses a gun disguised as a camera, only for it to literally backfire because he left the lens cap on.
- Happens on Dexter's Laboratory, when Deedee takes photos of his lab and plans to show it to their mom. Fortunately for him, his lab is barely seen due to Deedee's fingers being in the way.
- Jonny Quest episode "The Sea Haunt": Hadji tries to take a picture of the title monster but all there is on the photograph is a fingerprint.
- In The Flintstones, Fred and Barney capture the legendary whale Adobe Dick and Barney takes a photo of it before it escapes. Unfortunately, the picture was covered by Barney's thumb, which was a Running Gag earlier in the episode.
- The Invader Zim episode Megadoomer had this happen at the end, with the Humongous Mecha's Invisibility failed and Dib tried to take pictures of it.
- When SpongeBob SquarePants made a movie of Mermaid Man and Barnacle Boy, cameraman Patrick left the lenscap on so he wouldn't misplace it.