Using a camera flash while photographing the night sky can create the illusion of stars appearing brighter, but this effect is not due to the flash illuminating distant stars. Instead, the flash may increase the contrast of the star field by briefly enhancing the visibility of stars already present in the image. This phenomenon occurs because the flash can trigger a threshold of photon counts on the retina, allowing for a momentary perception of increased brightness. The discussion also touches on how photographic film and human vision both require a certain number of photons to register an image. Ultimately, the perceived brightness of stars when using a flash is likely an optical illusion rather than an actual increase in their luminosity.
