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

Re: The 1952 Tremonton Utah 'Seagulls'

From: Bruce Maccabee <brumac.nul>
Date: Fri, 20 Jul 2007 09:50:27 -0400
Archived: Fri, 20 Jul 2007 10:27:21 -0400
Subject: Re: The 1952 Tremonton Utah 'Seagulls'


>From: Michael Tarbell <mtarbell.nul>
>To: ufoupdates.nul
>Date: Wed, 18 Jul 2007 13:01:52 -0600
>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

>This is an interesting and handy relationship. I am still not
>sure how to interpret the Exposure term. Typically the argument
>to the logarithm function is a normalized (dimensionless)
>quantity. For example, if E0 were the exposure that gives
>exactly the true 'geosize', then the expression might take the
>form

>I = geosize + K log(E/E0)

>However, this can't be right, since it suggests that
>underexposing (E < E0) can make the object appear smaller than
>its geosize. What do you actually use as the argument to the log
>function?

This is a function that provides an empirical fit to the data
for the particular type of film. In the experiments did with
color reversal film (Fujichrome RD-400) at very low exposure
levels the image did, in fact, shrink a small amount below the
geosize. However, the main point is that this function is not
intended to represent image size at all exposure settings. (If
it did, exposure zero would correspond to a negative image
size.) The units could be (lm.sec/cm^2).

This function has been known to astronomers for a hundred(?)
years. It relates the size of star images to the brightness (or
"magnitude") of stars since geosize for a star is essentially
zero. There is, of course, also the diffraction and aberration
effects which increase the image size. See. C.E.K. Mees, The
Theory of the Photographic Process, McMillan, N.Y.C. 1944.



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