just about anyone can find evidence of ghosts using a common device in nearly every home: a camera. Orbs have also been reported in connection with crop circles and UFOs; they are a good, all-around “unexplained” phenomenon that can be adapted to fit many paranormal scenarios.
Most orbs are simply round or oval white shapes, though they may take a variety of forms. There is not one blanket cause for all orbs; many things can create the phenomena, ranging from insects to dust. In a series of experiments, I was able to create orb photos under a wide range of circumstances. The easiest way to create orbs is to take a flash photograph outdoors on a rainy night. The flash will reflect off of the individual droplets and appear as dozens of white, floating orbs. (The effect is most pronounced in a light rain, though even a little moisture in the air can create mysterious orbs.) CSI Senior Research Fellow Joe Nickell (1994), in his own studies, found that flashes reflecting back from camera straps are a common source of orbs, as are unnoticed shiny surfaces that can reflect a camera flash...
For the rest of the article, go here:
The (Non)Mysterious Orbs
Skeptical Inquirer Volume 31.5, September / October 2007
Reference cited by Radford:
Nickell, Joe. 1994. Camera Clues: A Handbook for Photographic Investigation
. Lexington, Kentucky: University of Kentucky Press.
Orbs are also sometimes called backscatter, orb backscatter, or near-camera reflection. Some orbs appear with trails indicating motion.
Orbs are photographic artefacts – specifically bits of airborne dust, water droplets, insects etc. caught in the flash of a camera. They appear out of focus because they are so close to the lens of the camera in an area called ‘The orb zone’ which is between the camera lens and the ‘point of focus’ in a photograph (namely the object you are taking a photo of, such as a person.)
When the flash of a camera goes off it will reflect off of the airborne artefacts in ‘the orb zone’ and the position between the lens and the ‘point of focus’ will cause the light reflection to appear as a circle of confusion.
An orb is what a professional photographer would call a circle of confusion, an out of focus highlight in the photo. When you take a photograph that has out of focus objects in it you will notice that the out of focus objects don’t just go fuzzy – they turn into small overlapping circles of light and the larger the circle, the fainter it is, because the light is more spread out until eventually the circles will become so large and faint that they disappear all together.
This could explain why some orbs appear larger and fainter than others rather than the idea that the spirit orb is further away from the camera. To confuse an artefact in front of a camera lens for a spirit manifestation is an easy mistake to make if you do not research into the subject and rely upon pseudo-scientific theories.
A study was done by ‘Paranormal Site Investigators’ who are based in Swindon into the orb phenomena that showed how it's unlikely that these balls of light are caused by ghosts.
The study can be found here: [www.theorbzone.com
There's another optical effect called boke (pronounced boh kay)