These have been debated between paranormal groups since the birth of the digital camera, not many people know this but orbs will not show up in a normal film camera as well, they just aren’t as sensitive to this phenomenon as the digital. It was only in 1972 that the digital camera came to be, but it wasn’t released as a commercial product until 1981 by Sony (Mavica). At first these strange orbs in the picture were just thought of as minor faults and a few cameras were returned, tested and sent back to the owner. Only after examining photographs and how light refracts through the lens to the chip in the digital camera had they worked out what is illuminated dust particles. This is where the debate started, when some bright spark came up with the idea that an Orb was a ghost. Some investigators believe this to be true, this is understandable, but there are other explanations that we must consider.
Lets break down an Orb, it’s round, and transparent, the same as a dust particle – dust is made up of just about everything, it is composed primarily of things like human skin and hair, waxes, pollen, mold, fungi, lichen, tiny particles of wood, paint, fibers from fabrics such as wool, nylon, rayon, foam rubber, sheet rock, plant and vegetable matter, insect parts and of course every form of pollution such as auto and industrial emissions, heavy hydrocarbon waste from oil or gas heaters, even tiny bits of metal debris from door hinges or any place where metal and friction meet.
Given the sheer amount of particles in the air how can we be certain the orb is anything but dust?
We will look at how such a tiny particle can look like a spooky encounter. You have a dust particle floating past your camera lens, very close, you take your photo, the flash goes off and lights up the dust particle. Here is a good example, these photo’s were taken at the Old Theater in Nelson as you can see orb city, it was so bad you could taste it.
As you can see, if you were a believer in Orbs, this would be the one of the most haunted places in New Zealand. Sorry to disappoint you, but it’s about as haunted as my left foot and we found no evidence of paranormal activity whatsoever, despite this premises being the oldest recorded theatre in New Zealand.
Ok what about blue and green orbs, ones that are out side you say, look at your surroundings, is there a mist in the air or perhaps rain floating about, these will appear with tails if it is raining and looks like they are going up not coming down due to the internal mirrors in your camera. I tend to take careful note of the colour of the hand rails for example, light will reflect off anything, whether it is a shiny surface or a powder coated bracing strut.
I know I seem to be taking all the fun out of investigating but if you want to be taken seriously as an investigator, all probable causes need to be taken into consideration. But if you want to believe that Orbs are a paranormal event then I will continue to believe in Santa Claus 
It’s your choice.