Re: Mysterious "orbs" on photos - ghosts or bunkum

[EMAIL PROTECTED] (Paul Lee) wrote in 
news:[EMAIL PROTECTED]:

> Hi everyone,
> This is my first post here, so please be gentle with me :)
> 
> I am performing some research on the little spheres seen on digital
> and 35mm
> photographs, touted by many as "evidence" of "ghosts". However, many
> reputable
> people simply dismiss them as drops of water or dust illuminated by
> the camera's flash (a view that I hold). It is many years since I did
> optics, and it never was one of my favourite subjects (and it was so
> long ago, it didn't cover recent developments in technologys such as
> CCDs etc.!)
> 
> I was wondering if you would care to look at some of my thoughts - as
> well as a dispatch I recently received from Canon on my website:
> http://www.btinternet.com/~dr_paul_lee/orbs.htm
> - what I would like is for some of the technical jargon to be
> explained,
> something that is beyond me and which might convince the lay person
> once and for all that these orbs are a load of rubbish. If possible, I
> would
> like to place some further comments on my webpage, with attribution
> naturally.
> 
> Best wishes to you all
> 
> Paul

        Hi Paul,

        I have, from time to time, evaluated photographs of various phenomena 
that has been touted as being from unexplained or supernatural origins, 
strictly from an amateur standpoint. These included mysterious objects in 
the sky, ghost and seance pics, and 'orbs'.

        What you have been told regarding the mundane cause for orbs is 
perfectly correct, and extremely easy to duplicate. I even reproduced the 
effect unintentionally last weekend when shooting in heavy fog with a 
digital camera ;-). You will also tend to see it with point-n-shoot film 
cameras that have a flash too close to the lens, the same ones that produce 
redeye so frequently. One person trying to convince a gullible audience 
used a lens spotted with water, reproducing the effect in the daytime. He 
aimed at a dark background and let a significant amount of diffuse light 
hit the lens directly. The defracted light became apparent, where in many 
circumstances it would have been overpowered by the brightness of a normal 
subject and simply been unnnoticeable, except by close inspection, as a 
vague softness in certain areas of the photo. I also provided an 
explanation of a similar effect, flash-illuminated raindrops, to the 
webmaster of one 'mysteries' site, but oddly enough, received no response 
or saw any update to his text which claimed that no one had given any kind 
of plausible explanation ;-)

        Not sure what the technical jargon is that you would like explained, 
with a couple of possible exceptions. 'CCD' simply stands for 'charge 
coupled device', which is meaningless unless you're into advanced 
electronics - but all it refers to is the digital sensor that captures the 
image. 'Depth of field' refers to the amount of focus distance on either 
side of the focused 'plane' or any camera or lens. You might focus on an 
object six feet away, but objects at four feet (closer) and ten feet 
(farther) are acceptably sharp at certain settings and/or focal lengths. 
Digital cameras do have a greater apparent depth-of-field, mostly from 
using shorter focal lengths than film cameras to achieve the same photo.

        You'll notice that, as something goes further out of focus, it 
becomes fuzzier, less distinct, and darker. So the lower (shorter) the 
depth of field on a camera, the less likely you are to see anything 
extremely close to the lens - it becomes so indistinct that it has minimal 
effect on the image. With greater depth of field, however, the focus 
becomes sharper, the objects brighter and more defined. Moreover, as I 
indicated above, you get a stronger effect when the flash sits very close 
to the lens, because the reflection of the light is more direct, not as 
scattered by the oblique angle of the light. Water droplets have an even 
stronger effect with such flashes, since you can get reflections from both 
surfaces - the closest one to you, and the back side from light passing 
through the droplet.

        I hope this helps, but feel free to throw any more questions my way. 
I have personally found, however, that to many people explanations such as 
this are quite unwelcome and may fall on deaf ears. There's just something 
too compelling about the supernatural.

        So good luck! 


        - Al.

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