"When I consider how many orb photos are taken outdoors in grassy cemeteries and around old buildings, it is not hard to extrapolate my experience out to encompass those settings. One person's report on this site says that he gets more orbs in photos when more people are in his field -- which would make sense, as more people walking about would stir up more insects.

"One researcher, whom I shall not name (but she should know better), published some orb photos in one of her books. The subject of the photos was a megalithic stone ring in a grassy area. The book did have some discussion regarding the idea that orbs might be caused by 'refraction off of moisture droplets in the air', as I recall. But this notion was discounted, and the implication was that the orbs were supernatural in nature.

"This is a trend which I have been alarmed to see growing in recent years. The name change from 'image anomaly' to 'orb' is understandable -- a handy label for discussion. But I was watching a TV show on ghosthunting the other night, and one of the researchers used the term "entity" for an orb phenomenon! Can this leap be warranted? I think such casual labeling imperils the credibility ghost hunters strive so hard to establish.

"Some things to keep in mind when looking at orb photographs:

They are almost always digital photos, and almost always flash photos. Some people will say their flash wasn't on, which on most cameras means it was and they didn't know it. The automatic exposure control on most cameras uses fill flash in all but brightest light. (The above-mentioned photos of the stone circle were from an overcast British day -- when asked, the photographer 'didn't think' the flash was on.)

Orb photos were rare before digital cameras became common.

Since most orb photos are produced using digital cameras, some folks like to propose that digital cameras are 'superior for orb photography'. Well, since they provide more orb photos, this is demonstrably true. But the digital imaging chip is markedly different from traditional film photography, and in terms of imaging is actually far inferior (until you get up into very expensive units). As anyone knows who has tried to blow up a digital image, the level of detail is inferior to most films. Digital images are gained from the contrast between pixels, between neighboring pixels and the image as a whole. By the very nature of the recording medium, digital images are "blockier" and contrast on individual pixels can easily be exaggerated in the final image.

Most digital cameras utilize a fixed, infinite-focus lens. Since there is no depth of field involved, the image makes little distinction between near and distant objects.

Most of the above also holds true for digital video cameras. The imaging chips are similar to those in digital still cameras, and most video recording is done with bright spotlights. Thus -- moving pictures of orbs. (Only high-end video cameras offer any sort of depth-of-field adjustment -- the average consumer model basically utilizes an infinite-focus lens.)

"While insects are less common indoors, I still suspect that insects as well as dust could explain many orb photos taken inside structures. Even the best-kept house may have insects or fleas brought in on pets, and the flying insect you can't discern in standard lighting may well gleam in a flash photo. (When you change a light bulb, aren't there often tiny winged insect carcasses in the light diffuser? We share our homes with more insects than we care to think of.)"

For those readers who wish to conduct their own experiments along the lines that Scott mentions above, he suggests carrying out the following at around dusk for better contrast:

"Have your camera set to flash. Walk around a grassy area a few times, sweep the grass with your feet, shake the bushes. Then stand still and hold your camera out to your side.
(You can try holding it beside your head, beside your shoulder, at arm's length, above your head, etc.)
Let your eyes defocus a bit, then click the shutter. If there are insects in the air, you may well see them with your naked eye as they reflect the camera's strobe. They look like little strobes themselves, or fireworks.
You can occasionally see this effect through the camera's viewfinder, but it is much easier to notice when the light source is coming from beside you.

"I suspect it is the wing surface of the flying insects which provides most of the area of reflection. Since the wings are beating rapidly, out of the insects in the camera's field of view only a certain number would have their wings at the correct angle at the moment of strobe to provide reflection directly back at the camera's lens. But even very tiny insects have an appreciable surface area of wing in relation to their bodies -- little versions of the bounce reflectors used by photographers!

"If you have seen with your bare eyes the insects flash in the strobe, and then see "orbs" in the photo you took at that moment, it is hard to doubt the connection.

"As mentioned, a good bright spotlight (mine is a theater-type "baby spot", but there are many other types) will provide another check. Hold it still, and the insects will come to you.
Sometimes there are so many tiny insects about the light it feels like you are underwater, and you wonder how you keep from breathing them in. Sweep it around, and you will see insects flare in reflection as the beam passes across them.