Lens flare in the context of Optical path

Spirit photography (also called ghost photography) is a type of photography whose primary goal is to capture images of ghosts and other spiritual entities, especially in ghost hunting. It dates back to the late 19th century. The end of the American Civil War and the mid-19th Century Spiritualism movement contributed greatly to the popularity of spirit photography. The omnipresence of death in the Victorian period created a desire for evidence of the afterlife, and those who partook in spirit photography oftentimes hoped to receive images that depicted the likeness of a deceased relative or loved one. Photographers such as William Mumler and William Hope ran thriving businesses taking photos of people with their supposed dead relatives. Both were shown to be frauds, but "true believers", such as Sir Arthur Conan Doyle, refused to accept the evidence as proof of a hoax.

As cameras became available to the general public, ghost photographs became common due to natural camera artifacts such as flash reflecting off dust particles, a camera strap or hair close to the lens, lens flare, pareidolia, or in modern times, deceptions using smart phone applications that add ghost images to existing photographs.

Spirit photography (also called ghost photography) is a type of photography whose primary goal is to capture images of ghosts and other spiritual entities, especially in ghost hunting. It dates back to the late 19th century. The end of the American Civil War and the mid-19th Century Spiritualism movement contributed greatly to the popularity of spirit photography. The omnipresence of death in the Victorian period created a desire for evidence of the afterlife, and those who partook in spirit photography oftentimes hoped to receive images that depicted the likeness of a deceased relative or loved one. Photographers such as William Mumler and William Hope ran thriving businesses taking photos of people with their supposed dead relatives. Both were accused of fraud, but "true believers", such as Sir Arthur Conan Doyle, refused to accept the evidence as proof of a hoax. Though taken to court, Mumler was eventually acquitted of all charges. They were never able to prove his methods.

As cameras became available to the general public, ghost photographs became common due to natural camera artifacts such as flash reflecting off dust particles, a camera strap or hair close to the lens, lens flare, pareidolia, or in modern times, deceptions using smart phone applications that add ghost images to existing photographs.

An in-camera effect is any visual effect in a film or video that is created solely by using techniques in and on the camera and/or its parts. The in-camera effect is defined by the fact that the effect exists on the original camera negative or video recording before it is sent to a lab or modified. Effects that modify the original negative at the lab, such as skip bleach or flashing, are not included. Some examples of in-camera effects include the following:

• Matte painting
• Schüfftan process
• Forced perspective
• Dolly zoom
• Lens flares
• Lighting effects
• Filtration such as using a fog filter to simulate fog, or a grad filter to simulate sunset.
• Shutter effects.
• Time-lapse, slow motion, fast motion, and speed ramping.
• Bipacks
• Slit-scan
• Infrared photography
• Reverse motion
• Front projection
• Rear projection
• Phonotrope a live animation technique that uses the frame-rate of a camera

There are many ways one could use the in-camera effect. The in-camera effect is something that often goes unnoticed but can play a critical part in a scene or plot. A popular example of this type of effect is seen in Star Trek, in which the camera is shaken to give the impression of motion happening on the scene. Another simple example could be using a wine glass to give the effect that "ghosting, flares, and refractions" from DIY photography.