Uncanny Atlas
Tool

Polaroid photography

Ghost hunters use instant cameras such as Polaroids to get a physical print on the spot as evidence.

What users say it does
The Buried Secrets podcast says instant photography has grown popular for ghost photos because a print that appears at once seems to leave no room for fakery. Joe Nickell and the New England Skeptical Society describe Polaroid effects that some photographers took as signs, such as angel wings and a Golden Door read as the doorway to heaven in Revelation 4:1.
What it measures
Wikipedia explains that instant print film works by diffusion transfer, with a reagent moving dyes out of the negative and onto the print.

Photographs offered as proof of spirits predate the Polaroid. In 1862, Wikipedia says, American engraver William Mumler published a photograph taken in a Boston studio that he said showed the spirit of a cousin dead for 12 years, and he went on to work as a spirit photographer.

Joe Nickell, in a 2022 Skeptical Inquirer article, reviewed photos a Sunday school teacher had taken and found by experiment that the so-called angel wings came from light leaking into a Polaroid's film pack, which can happen when a thumb riffles the pack as it goes into the camera. The New England Skeptical Society reports that Georgia skeptic Dale Heatherington reproduced the Golden Door effect reliably with a Polaroid camera pointed at a bright light.

Sources