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Location: UFOUpDatesList.Com > 2007 > Jul > Jul 20

Re: The 1952 Tremonton Utah'Seagulls'Confirmation?

From: Bruce Maccabee <brumac.nul>
Date: Fri, 20 Jul 2007 09:50:15 -0400
Archived: Fri, 20 Jul 2007 10:25:40 -0400
Subject: Re: The 1952 Tremonton Utah'Seagulls'Confirmation?


>From: Martin Shough <parcellular.nul>
>To: <ufoupdates.nul>
>Date: Wed, 18 Jul 2007 18:04:00 +0100
>Subject: Re: The 1952 Tremonton Utah'Seagulls'Confirmation?

>>From: Bruce Maccabee <brumac.nul>
>>To: <ufoupdates.nul>
>>Date: Tue, 17 Jul 2007 18:35:59 -0400
>>Subject: Re: The 1952 Tremonton Utah 'Seagulls'Confirmation?

<snip>

>How do the edges of the image behave as it grows with this
>flaring? Al Chop is quoted as saying that these were "burned
>right down to the celluloid", which I take to mean the negative
>is saturated in the image areas (don't know if this applies to
>both sides of the f/stop change) but the edges are said to be
>"sharp".

Sideways scattering of light within the film could produce a
"blurred" edge. But the problem in answering this question is
the definition of "sharp". What was the distance from complete
exposure to unexposed (measuring from inside an image to the
outer boundary)? The distance would be measured in microns
(thousandths of a millimeter). Without knowing how many microns
from a location of maximum exposure to a location of no exposure
(or sky exposure) I really can't answer the question. In all
cases, the center of the image is brightness and the brightness
(actually transparency) of the image diminishes as one measures
from the center outwards. The response of the film to light is
non-linear (more like logarithmic) which complicates the issue.

>Hartmann says that "when the objects dimmed
>sufficiently they faded out entirely with no dark dot or
>silhouette being visible", implying that most if not all of the
>image size is due to overexposure, which allows the angular
>source size to be small enough for unresolved birds.

Again, the center of the image is brightest for a small bright
light source so it would be the 'last to go' even if the image
were large enough to be resolved. As the objects move away their
image size would shrink from the distance increase. So it would
be difficult to argue that the size is totally a result of
brightness.

>On the
>>other hand the further away the bird is not only the faster it
>>needs to fly but the more efficiently it needs to reflect the
>>sun. Wouls it be possible to put a lower limit on the light flux
>>at the emulsion and then infer the emitted/reflected intensity
>>from general principles? (I think the NPIC did something like
t>>his because they decided gulls were "not sufficiently actinic"
>but I don't know the detail of how they did it)

Tough because there is skylight to contend with.

>I take it you haven't had the chance to work on this film
>yourself? Would you like to? (Not that I can do anything about it
>of course, I'd just like to see your results.)

I've seen it... in the UFO movie... but never had the film
itself to work with. I'm sure I would look at it if available.
But others have spent 'thousands of hours'. Don't know that I
could do any better.



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