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Location: UFOUpDatesList.Com > 2013 > Aug > Aug 18

Re: 1971 Costa Rican Photo Is Prosaic Object

From: Edward Gehrman <egehrman.nul>
Date: Sun, 18 Aug 2013 08:05:06 -0700
Archived: Sun, 18 Aug 2013 17:33:55 -0400
Subject: Re: 1971 Costa Rican Photo Is Prosaic Object


>From: Albert Baier <albertgbaier.nul>
>To: UFO UpDates - Toronto <post.nul>
>Date: Tue, 30 Jul 2013 14:42:23 -0500
>Subject: Re: 1971 Costa Rican Photo Is Prosaic Object

>>From: Edward Gehrman <egehrman.nul>
>>To: <post.nul>
>>Date: Mon, 29 Jul 2013 07:27:21 -0700
>>Subject: Re: 1971 Costa Rican Photo Is Prosaic Object


>Ed, Bob:

>1. The Haines/Vallee report did not use the original negative.
>There is no provenance or chain of custody mentioned for the
>copies used.

>2. Focus is dependent on lens to film distance. Fixed focus
>(non-zoom) lenses can be used at any subject distance, provided
>the lens-to-film distance is correct.

>3. Lenses for aerial photography (like the Zeiss lens used) are
>designed to render images that have very low optical distortion,
>so that objects can be measured accurately. Good color
>correction is required so that the frequency range of the film
>focuses at the same plane. They must be fast, and cover a 9" x
>9" film area. This makes them expensive.

>4. The object is brighter than the background, which is easy to
>fake. Dark on a light background is harder, but still possible.

>In view of point 1., IMO, no definite conclusions can be made,
>but I lean toward the prosaic.

>BTW: The frames shown in the report represent some of the worst
>aerial photography I've ever seen. Surely the Zeiss RMK 15/23
>is capable of better images. Something's not right here.


Albert, List,

I sent your response to Bob and below is his reply:

-----

Albert,

1) Agreed.

2) No. You have only half of the equation. Focus is dependent on
the distance from the lens to the plane of focus (film or
digital sensor,) and the lens to the subject distance. The two
are inversely related; as the lens to subject distance gets
shorter the lens to plane of focus distance gets longer, to
maintain focus. That's why macro lenses get longer as you focus
in close. This is true for simple lenses, biconvex or plano-
convex. Things become more complicated when you deal with
modern, multi-element lenses, most of which focus by movement of
internal elements or lens groups rather than movement of the
whole lens. A complex lens, like the Zeiss aerial lens in
question, may have internal focus, but aerial camera lenses do
not, since they are designed for use at only one distance.
Typically they do not focus at all and are factory set at
infinity focus.

You confuse fixed focus lenses (which do not focus at all) and
fixed focal length lenses, which is what non-zoom lenses
typically are. All lenses made for photographic use have a set
focus range, from infinity at one end to whatever the closest
focus is at the other. Aerial camera lenses like we're talking
about are fixed focus (infinity) and do not focus closer.
Without modification, one could not be used to image a
flashlight close to the lens.

If you question my qualifications to talk about such things,
take a look on Amazon.com and do an author search on Bob Shell
and you will see some of the 28 books I've written about
photography, most of them technical. Or consult Applied
Photographic Optics by Les Stroebel, who teaches optics at RIT.

3) OK. Most aerial camera lenses are achromatic or apochromatic.
Achromatic lenses focus two colors of visible light on the same
plane at the same image size, while apochromatic lenses focus
all three colors of visible light on the same plane and at the
same image size. High tolerances and very limited production
contribute to the high prices.

4) Not so. Either is quite easy to fake. Much easier today, of
course.

5.No comment on the quality of the photography.

Bob

---

List,

It's always tiresome to me when someone posts some photographic
half-truth like this. Never have I seen so many half-baked photo
'experts' as in the UFO field. Most don't know a lens from a
hole in the ground!

It's particularly frustrating when someone like Albert has
absorbed half of the story. Optics I know. Back in the early
80's I worked with Dr. Siegfried Schaffer, the chief optical
designer at ENNA-WERK in Munich. Schaffer is co-inventor of the
zoom lens (with Frank Back) and designed one of the first
commercially available zoom lenses. He stayed in Munich while
Back immigrated to the USA and founded Zoomar Corp., making
lenses for the motion picture industry initially, and later for
still photography.

The first use of a zoom lens that I'm aware of was by Leni
Riefenstahl in her 1936 film Triumph Of Will. I'm pretty sure it
was one of Frank Back's prototypes.

He kept his manufacturing in Munich. One of my best
friends, Herwig Zorkendorfer, worker for him there as a
designer and has his own specialty optics firm now.

www.Zork.com

Anyway, I was involved in the design of slide projector lenses,
slide viewers, and some other optical products. I'm not on the
same level as Schaffer, Back, and Zorkendorfer, but my knowledge
of optics is well beyond the average photographer.

Bob Shell

-----

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