Re: [tech-3d] Digest Number 35

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

----- Original Message -----
From: <tech-3d@xxxxxxxxxxx>
To: <tech-3d@xxxxxxxxxxx>
Sent: Saturday, November 25, 2000 3:56 AM
Subject: [tech-3d] Digest Number 35


>
> There are 2 messages in this issue.
>
> Topics in this digest:
>
>       1. Re: Digest Number 33
>            From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
>       2. Re: Digest Number 33
>            From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
>
>
> ________________________________________________________________________
> ________________________________________________________________________
>
> Message: 1
>    Date: Fri, 24 Nov 2000 21:04:50 -0800
>    From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
> Subject: Re: Digest Number 33
>
>
> ----- Original Message -----
> From: <tech-3d@xxxxxxxxxxx>
> To: <tech-3d@xxxxxxxxxxx>
> Sent: Thursday, November 23, 2000 12:50 PM
> Subject: [tech-3d] Digest Number 33
>
>
> >
> > There are 4 messages in this issue.
> >
> > Topics in this digest:
> >
> >       1. Re: holographic 3d
> >            From: lunazzi <lunazzi@xxxxxxxxxxxxxx>
> >       2. Re: Stereo Base Calculation with a $20.00 Handheld
> >            From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> >       3. Why consider ratio of Viwer FL to Camera FL?
> >            From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> >       4. Re: Re: Stereo Base Calculation with a $20.00 Handheld
> >            From: Andres Posada O <aposadao@xxxxxxxxxx>
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 1
> >    Date: Wed, 22 Nov 2000 15:20:19 -0200
> >    From: lunazzi <lunazzi@xxxxxxxxxxxxxx>
> > Subject: Re: holographic 3d
> >
> > Peter Homer wrote:
> >
> > > >The technique of projecting with mirrors is as old as 4000 years (the
> Incas and
> > > >the Olmecas). I did not think these new world civilisations were as
old
> as this
> > > which is as old or older than anything in the old world and I thought
> the Olmecs were the oldest rather than the Incas
> >
> > I do not know if they were older than the Incas, the interesting thing
is
> that they disappeared before the Aztecs but left a very important
influence
> on them. I do not know if Teotihuacan is considered precisely Olmec, but
it
> seems to be, and was considered as a sacred city when it was found
inhabited
> by the Aztecs.
> >
> > > but perhaps that was just in Central rather than South America
> > > >http://www.geocities.com/Athens/Forum/3853/olm1e.html
> > > >
> > > I had a look at this site although I could not view the graphics
> properly with my my Netscaoe Navigator 2.02,
> >
> > Maybe it is due to the version, because I use Netscape 4 now, although I
> started with 2.0
> > I verified by reading from a different terminal than I used for
editing,
> to avoid the direct lecture on the computer rather than through internet
(is
> a typical error that sometimes arrives to me).
> >
> > > I found it very interesting but was the original intention of the
> concave mirrors to project images or to focuss the suns rays to produce
> fire,as the name Tezcatlipoca ( smoking Mirror) suggests. Perhaps with a
> religious significance as the fire was taken directly from the sun,
> >
> > This was already made by the Incas, precisely as you wrote, but using
> metal mirrors.
> >
> > > I have seen some other illustrations of these types of mirrors made
from
> polished pyrite or iron sulphide FeS2 which can form naturaly in balls or
> discs
> >
> > I have some samples, but not in the form of balls or discs.
> >
> > > consisting of radiating needle like crystals. Specular haematite can
> also form a miror like surface when polished,
> > >
> >
> > I am trying a technician to made the polishing on them, using aluminum
> oxide.
> >
> > I would like to put more information on my page, including the whole
> article, but for the moment I can mail you the article if you send me your
> postal address.
> >
> > > >Projecting on lenses is also interesting, it renders a floating
image.
> > > >The progress in this last years shoul be in increasing the field of
> view, wether
> > > >using paraboloidal mirrors more specific that the Olmecas ones (as
> Peter Homer
> > > >indicated)
> > >
> > > P.J.Homer
> >
> > The serpent heads emerging in the Teotihuacan temples (pyramides) arises
> from mirrors (archeologist said), what shows clearly (at least to me) that
> mirrors were employed for imaging.  On the other hand, if they were merely
> to concentrate sun,  I can suppose that it did not needed so much
polishing.
> Another interesting feature is that most Olmec mirrors has two different
> focal lenghts (along perpendicular directions) what makes them to not
> concentrate light in focus.
> >
> > José
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 2
> >    Date: Wed, 22 Nov 2000 23:31:39 -0600
> >    From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> > Subject: Re: Stereo Base Calculation with a $20.00 Handheld
> >
> > Abram,
> >
> >
> > >Date: Mon, 20 Nov 2000 15:52:01 -0000
> > >From: "Abram Klooswyk" <abram.klooswyk@xxxxxx>
> > >Subject: Re: Stereo Base Calculation With a $20.00 Handheld
> >
> > [snip]
> >
> > >Michael Davis wonders why I call the so-called "General Solution"
> > >paradoxical.
> > >The formula is for base calculation, to get a base which results in
> > >a viewable deviation. Many newbies like such a rule. However, the
> > >formula next asks for an _input_ of the deviation which it should
> > >provide as _outcome_ on film, after _using_ the calculated base.
> > >Newbies will ask: what deviation?
> > >You can calculate it from the base, and than get in an endless
> > >regression. In discussions many different values for deviation are
> > >mentioned, which isn't particular helpful for newbies.
> >
> > There is no paradox.  You could apply your argument to the push-pull
> > relationship between aperture and shutter speed.  But unlike the
> > relationship between aperture and shutter speed, where we quite often
> > toggle between wanting to fix one and solve for the other, any hope of
> > calling the General Solution a parodox vanishes when we acknowledge that
> > Base is on one side of the equal sign, ALL BY ITSELF, and deviation is
one
> > of several variables on the other side.
> >
> > The General Solution is an equation.  The author had a reasonable
> > expectation that users would understand they are *solving for base*, NOT
> > solving for deviation, not solving for focal length, not solving for
near
> > point or far point, etc.  I have yet to see the General Solution
expressed
> > as a solution for deviation - with a  d  all by itself on one side of
the
> > equal sign and base specified as a variable along with all the others,
on
> > the other side of the equation.
> >
> > I can't imagine any newbies actually doing the math to rearrange the
> > General Solution in the first place, much less finding themselves in an
> > endless regression, solving for deviation, then for base, then for
> > deviation, then for base, etc.  Your argument is quite simply fantastic.
> >
> > Everyone I've read about or spoken to who uses the General Solution, is
> > completely content to use it for one purpose - solving for base.  Base
is
> > the output.
> >
> > The formula is used to deliver a base value that will PRODUCE the
on-film
> > deviation you have CHOSEN to specify as a variable.  The General
Solution
> > can deliver numerous bases, each unique to the scene described by the
Near
> > and Far variables, but these bases, though different from one scene to
the
> > next will CONSISTENTLY produce the CHOSEN on-film deviation, within the
> > range of bases permitted by your equipment and technique, of course.
> >
> > It is not at all difficult to select an on-film deviation value that
> > satisfies your personal taste for how much depth your images will have.
> >
> > My original post, as seen at
> >
> > http://www.pauck.de/archive/mailinglist/tech-3d/mhonarc/msg01919.html
> >
> > suggests shooting with bases that are calculated using a deviation equal
> to
> > 80% of the Maximum Allowable On-Film Deviation.  I also explained that
> > MAOFD is just the camera focal length divided by 30.   80% of MAOFD is
> just
> > a place to start.  Shoot a few rolls at 80% of MAOFD to get a feel for
it.
> > It's subjective.  It's up to you to determine if you find it appealing.
> If
> > 80% of MAOFD is a little too strong for you (too much "bite" for your
> > taste), try a few rolls at a lesser percentage.  The General Solution
will
> > deliver the exact same deviation on-film, every time.  And even if
you've
> > found that something like 75% MAOFD suits your needs most of the time,
> > there's nothing stopping you from CHOOSING more or less depth for a
> > particular scene you are about to shoot.  You are in control, but it's
> your
> > responsibility to get a feel for the numbers.
> >
> > [snip]
> >
> > >When you want to emphasize tiny scratches on ancient coins, stretch
> > >might be your purpose. But Michael Davis says:
> >
> > >>It is my personal preference to use a variable base,
> > >>following the General Solution, for nearly every situation,
> > >>including the mid-field.
> >
> > >When this would include a portrait of a person before a nearby
> > >"backdrop" I'm afraid I would call it weird, to say the least... :-).
> >
> >
> > It is apparent that your intention here is to suggest that in a
situation
> > where stretch might be desirable, I would use the General Solution and
> this
> > would somehow prohibit that goal.  This assertion is incorrect on two
> > counts.  First, using the General Solution, I can add stretch at will by
> > increasing the deviation used to calculation base.  The General Solution
> > does NOT have to be calculated using the Maximum Allowable OFD or any
> other
> > fixed value for deviation.  Second, the article from which you quote
> > clearly states that I abandon the General Solution at Near:Far ratios
less
> > than 1:2.  I discuss that at length across several paragraphs. (See the
> > link above.) Did you miss that portion of my article or are you just
> > spinning my words?
> >
> > I will vigorously defend your right to prefer more or less on-film
> > deviation than I do.  I will support your right to select and use
> equipment
> > and methodology that YOU find satisfying.  But I can not refrain from an
> > equally vigorous defense against absurd attacks on the truth embodied by
> > the General Solution.  The formula matches the geometry perfectly.  It
is
> > both valid and useful.
> >
> > Why must there be a steady onslaught of condemnation for something so
> > unambigous?   I'm convinced it's mostly just a matter of:
> >
> > ignorance (I don't know how to use it so I hate it.)
> > arrogance (My many years experience have canonized my techniques.)
> > pride (I will never admit I'm wrong about other people's techniques.)
> > laziness (I'll just burn a lot of film and see what I get.)
> > contentiousness (I live to stomp on other people.)
> >
> > or some combination of the above.
> >
> > Mike Davis
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 3
> >    Date: Wed, 22 Nov 2000 23:58:50 -0600
> >    From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> > Subject: Why consider ratio of Viwer FL to Camera FL?
> >
> > Hi Boris,
> >
> > >Date: Mon, 20 Nov 2000 17:33:48 -0500
> > >From: boris@xxxxxxxxxxxx
> > >Subject: Re: Stereo Base Calculation With a $20.00 Handheld
> >
> > [snip]
> >
> > >I have a question.  Why does a viewing device focal length (i.e. a
> viewing
> > >geometry) even come into play?  On film deviation is the product simply
> of
> > >camera optics, stereobase, and near and far point.  Why the viewer
F.L.?
> > >Granted, the viewer optics affect the perceived depth, but it certainly
> > >does not change OFD.
> > >
> > >(And for my application, in shooting for anaglyphs, there is no viewer
> F.L.
> > >There may be a print size, and a viewer's naked eye distance to print -
> > >that would form the equivalent to a viewer's focal length.  But to
shoot
> > >for a specific size anaglyph print, and therein a specific deviation on
> > >paper, I want to predict and set up a shot simply for a particular
> > >deviation on film.  Viewer optics are not otherwise considered.)
> > >
> > >Boris
> >
> > If you already know an on-film deviation that gives you the look you
like,
> > using whatever display mechanism you employ, then you need not be
> concerned
> > about compensating a mismatch between viewer focal length and camera
focal
> > length.
> >
> > I include this ratio of vFL to cFL as a factor in calculating base
because
> > just as sitting in the front row of a 3D theater causes squash not
> > experienced in the middle row, my camera lenses, being of shorter focal
> > length than my viewer lenses cause that same squash.  Increasing the
base
> > proportionately compensates this.
> >
> > I have a closeup 2D picture of my dog's face shot with an 18mm lens (on
a
> > 35mm body).  His nose is nearly the width of his forehead.  Viewed at a
> > distance of ten feet, he looks comical in this picture.  But if you view
> > the print at a distance equal to the camera focal length times the
> > enlargement factor, (about 8 inches for this 11x14 print), his
proportions
> > appear to be normal.
> >
> > Mike
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 4
> >    Date: Thu, 23 Nov 2000 08:04:25 -0500
> >    From: Andres Posada O <aposadao@xxxxxxxxxx>
> > Subject: Re: Re: Stereo Base Calculation with a $20.00 Handheld
> >
> >
> >
> > "Michael K. Davis" wrote:
> > >
> > >
> > > The General Solution is an equation.  The author had a reasonable
> > > expectation that users would understand they are *solving for base*,
NOT
> > > solving for deviation, not solving for focal length, not solving for
> near
> > > point or far point, etc.
> > >
> > > Everyone I've read about or spoken to who uses the General Solution,
is
> > > completely content to use it for one purpose - solving for base.  Base
> is
> > > the output.
> > >
> >
> > Michael:
> >    In my HP48G+ I can solve for what ever I want (anybody with the
> > formulas in a computer or the like may obviopusly do it). Doing 3D video
> > I am usually stuck to minimum camera separations, dictated by the camera
> > sizes, that require that I solve for near point, sometimes I need to
> > solve for far point. For example: if I have a minumum camera separation
> > due to camera size of say 165mm, and the nearest object is going to be
> > at 3000mm, then how far may the farthest object be, all this subjected
> > to a MOFD choosen according to CCD size, lens focal length and TASTE.
> > What happens to the near point if I change the focal length position in
> > the cameras zoom lenses? Everything changes if I use 1/3", 1/2", or 3/4"
> > CCDs cameras. MOFD numbers I change according obviously to CCD size, but
> > also I use more "liberal" numbers if all subjects are inside the window,
> > be more conservative with subjects way out of the window and near to the
> > camera. My point is I almost never solve for base.
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> >
> >
> >
>
>
>
> ________________________________________________________________________
> ________________________________________________________________________
>
> Message: 2
>    Date: Fri, 24 Nov 2000 21:20:16 -0800
>    From: "Don Lopp" <dlopp@xxxxxxxxxxxxxxx>
> Subject: Re: Digest Number 33
>
> Having built 10 MF viewers with lenses with focal legths of from 45mm to
> 80mm., I have come to the conclusion that shorter is better. An example is
> that I prefer to view  80mm stereo slides with viewer lenses of about 50mm
> because this makes the views look like Eyemax which is more than I can say
> about viewing 35 mm stereo when using the standard available viewers which
,
> mostly, have lenses of 42 to 45 mm lenses. My viewer with 28mm lenses is
> pretty good, but I wish I could find some 24 mm lenses that are useable ?
> DON
> ----- Original Message -----
> From: <tech-3d@xxxxxxxxxxx>
> To: <tech-3d@xxxxxxxxxxx>
> Sent: Thursday, November 23, 2000 12:50 PM
> Subject: [tech-3d] Digest Number 33
>
>
> >
> > There are 4 messages in this issue.
> >
> > Topics in this digest:
> >
> >       1. Re: holographic 3d
> >            From: lunazzi <lunazzi@xxxxxxxxxxxxxx>
> >       2. Re: Stereo Base Calculation with a $20.00 Handheld
> >            From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> >       3. Why consider ratio of Viwer FL to Camera FL?
> >            From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> >       4. Re: Re: Stereo Base Calculation with a $20.00 Handheld
> >            From: Andres Posada O <aposadao@xxxxxxxxxx>
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 1
> >    Date: Wed, 22 Nov 2000 15:20:19 -0200
> >    From: lunazzi <lunazzi@xxxxxxxxxxxxxx>
> > Subject: Re: holographic 3d
> >
> > Peter Homer wrote:
> >
> > > >The technique of projecting with mirrors is as old as 4000 years (the
> Incas and
> > > >the Olmecas). I did not think these new world civilisations were as
old
> as this
> > > which is as old or older than anything in the old world and I thought
> the Olmecs were the oldest rather than the Incas
> >
> > I do not know if they were older than the Incas, the interesting thing
is
> that they disappeared before the Aztecs but left a very important
influence
> on them. I do not know if Teotihuacan is considered precisely Olmec, but
it
> seems to be, and was considered as a sacred city when it was found
inhabited
> by the Aztecs.
> >
> > > but perhaps that was just in Central rather than South America
> > > >http://www.geocities.com/Athens/Forum/3853/olm1e.html
> > > >
> > > I had a look at this site although I could not view the graphics
> properly with my my Netscaoe Navigator 2.02,
> >
> > Maybe it is due to the version, because I use Netscape 4 now, although I
> started with 2.0
> > I verified by reading from a different terminal than I used for
editing,
> to avoid the direct lecture on the computer rather than through internet
(is
> a typical error that sometimes arrives to me).
> >
> > > I found it very interesting but was the original intention of the
> concave mirrors to project images or to focuss the suns rays to produce
> fire,as the name Tezcatlipoca ( smoking Mirror) suggests. Perhaps with a
> religious significance as the fire was taken directly from the sun,
> >
> > This was already made by the Incas, precisely as you wrote, but using
> metal mirrors.
> >
> > > I have seen some other illustrations of these types of mirrors made
from
> polished pyrite or iron sulphide FeS2 which can form naturaly in balls or
> discs
> >
> > I have some samples, but not in the form of balls or discs.
> >
> > > consisting of radiating needle like crystals. Specular haematite can
> also form a miror like surface when polished,
> > >
> >
> > I am trying a technician to made the polishing on them, using aluminum
> oxide.
> >
> > I would like to put more information on my page, including the whole
> article, but for the moment I can mail you the article if you send me your
> postal address.
> >
> > > >Projecting on lenses is also interesting, it renders a floating
image.
> > > >The progress in this last years shoul be in increasing the field of
> view, wether
> > > >using paraboloidal mirrors more specific that the Olmecas ones (as
> Peter Homer
> > > >indicated)
> > >
> > > P.J.Homer
> >
> > The serpent heads emerging in the Teotihuacan temples (pyramides) arises
> from mirrors (archeologist said), what shows clearly (at least to me) that
> mirrors were employed for imaging.  On the other hand, if they were merely
> to concentrate sun,  I can suppose that it did not needed so much
polishing.
> Another interesting feature is that most Olmec mirrors has two different
> focal lenghts (along perpendicular directions) what makes them to not
> concentrate light in focus.
> >
> > José
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 2
> >    Date: Wed, 22 Nov 2000 23:31:39 -0600
> >    From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> > Subject: Re: Stereo Base Calculation with a $20.00 Handheld
> >
> > Abram,
> >
> >
> > >Date: Mon, 20 Nov 2000 15:52:01 -0000
> > >From: "Abram Klooswyk" <abram.klooswyk@xxxxxx>
> > >Subject: Re: Stereo Base Calculation With a $20.00 Handheld
> >
> > [snip]
> >
> > >Michael Davis wonders why I call the so-called "General Solution"
> > >paradoxical.
> > >The formula is for base calculation, to get a base which results in
> > >a viewable deviation. Many newbies like such a rule. However, the
> > >formula next asks for an _input_ of the deviation which it should
> > >provide as _outcome_ on film, after _using_ the calculated base.
> > >Newbies will ask: what deviation?
> > >You can calculate it from the base, and than get in an endless
> > >regression. In discussions many different values for deviation are
> > >mentioned, which isn't particular helpful for newbies.
> >
> > There is no paradox.  You could apply your argument to the push-pull
> > relationship between aperture and shutter speed.  But unlike the
> > relationship between aperture and shutter speed, where we quite often
> > toggle between wanting to fix one and solve for the other, any hope of
> > calling the General Solution a parodox vanishes when we acknowledge that
> > Base is on one side of the equal sign, ALL BY ITSELF, and deviation is
one
> > of several variables on the other side.
> >
> > The General Solution is an equation.  The author had a reasonable
> > expectation that users would understand they are *solving for base*, NOT
> > solving for deviation, not solving for focal length, not solving for
near
> > point or far point, etc.  I have yet to see the General Solution
expressed
> > as a solution for deviation - with a  d  all by itself on one side of
the
> > equal sign and base specified as a variable along with all the others,
on
> > the other side of the equation.
> >
> > I can't imagine any newbies actually doing the math to rearrange the
> > General Solution in the first place, much less finding themselves in an
> > endless regression, solving for deviation, then for base, then for
> > deviation, then for base, etc.  Your argument is quite simply fantastic.
> >
> > Everyone I've read about or spoken to who uses the General Solution, is
> > completely content to use it for one purpose - solving for base.  Base
is
> > the output.
> >
> > The formula is used to deliver a base value that will PRODUCE the
on-film
> > deviation you have CHOSEN to specify as a variable.  The General
Solution
> > can deliver numerous bases, each unique to the scene described by the
Near
> > and Far variables, but these bases, though different from one scene to
the
> > next will CONSISTENTLY produce the CHOSEN on-film deviation, within the
> > range of bases permitted by your equipment and technique, of course.
> >
> > It is not at all difficult to select an on-film deviation value that
> > satisfies your personal taste for how much depth your images will have.
> >
> > My original post, as seen at
> >
> > http://www.pauck.de/archive/mailinglist/tech-3d/mhonarc/msg01919.html
> >
> > suggests shooting with bases that are calculated using a deviation equal
> to
> > 80% of the Maximum Allowable On-Film Deviation.  I also explained that
> > MAOFD is just the camera focal length divided by 30.   80% of MAOFD is
> just
> > a place to start.  Shoot a few rolls at 80% of MAOFD to get a feel for
it.
> > It's subjective.  It's up to you to determine if you find it appealing.
> If
> > 80% of MAOFD is a little too strong for you (too much "bite" for your
> > taste), try a few rolls at a lesser percentage.  The General Solution
will
> > deliver the exact same deviation on-film, every time.  And even if
you've
> > found that something like 75% MAOFD suits your needs most of the time,
> > there's nothing stopping you from CHOOSING more or less depth for a
> > particular scene you are about to shoot.  You are in control, but it's
> your
> > responsibility to get a feel for the numbers.
> >
> > [snip]
> >
> > >When you want to emphasize tiny scratches on ancient coins, stretch
> > >might be your purpose. But Michael Davis says:
> >
> > >>It is my personal preference to use a variable base,
> > >>following the General Solution, for nearly every situation,
> > >>including the mid-field.
> >
> > >When this would include a portrait of a person before a nearby
> > >"backdrop" I'm afraid I would call it weird, to say the least... :-).
> >
> >
> > It is apparent that your intention here is to suggest that in a
situation
> > where stretch might be desirable, I would use the General Solution and
> this
> > would somehow prohibit that goal.  This assertion is incorrect on two
> > counts.  First, using the General Solution, I can add stretch at will by
> > increasing the deviation used to calculation base.  The General Solution
> > does NOT have to be calculated using the Maximum Allowable OFD or any
> other
> > fixed value for deviation.  Second, the article from which you quote
> > clearly states that I abandon the General Solution at Near:Far ratios
less
> > than 1:2.  I discuss that at length across several paragraphs. (See the
> > link above.) Did you miss that portion of my article or are you just
> > spinning my words?
> >
> > I will vigorously defend your right to prefer more or less on-film
> > deviation than I do.  I will support your right to select and use
> equipment
> > and methodology that YOU find satisfying.  But I can not refrain from an
> > equally vigorous defense against absurd attacks on the truth embodied by
> > the General Solution.  The formula matches the geometry perfectly.  It
is
> > both valid and useful.
> >
> > Why must there be a steady onslaught of condemnation for something so
> > unambigous?   I'm convinced it's mostly just a matter of:
> >
> > ignorance (I don't know how to use it so I hate it.)
> > arrogance (My many years experience have canonized my techniques.)
> > pride (I will never admit I'm wrong about other people's techniques.)
> > laziness (I'll just burn a lot of film and see what I get.)
> > contentiousness (I live to stomp on other people.)
> >
> > or some combination of the above.
> >
> > Mike Davis
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 3
> >    Date: Wed, 22 Nov 2000 23:58:50 -0600
> >    From: "Michael K. Davis" <zilch0@xxxxxxxxxxxx>
> > Subject: Why consider ratio of Viwer FL to Camera FL?
> >
> > Hi Boris,
> >
> > >Date: Mon, 20 Nov 2000 17:33:48 -0500
> > >From: boris@xxxxxxxxxxxx
> > >Subject: Re: Stereo Base Calculation With a $20.00 Handheld
> >
> > [snip]
> >
> > >I have a question.  Why does a viewing device focal length (i.e. a
> viewing
> > >geometry) even come into play?  On film deviation is the product simply
> of
> > >camera optics, stereobase, and near and far point.  Why the viewer
F.L.?
> > >Granted, the viewer optics affect the perceived depth, but it certainly
> > >does not change OFD.
> > >
> > >(And for my application, in shooting for anaglyphs, there is no viewer
> F.L.
> > >There may be a print size, and a viewer's naked eye distance to print -
> > >that would form the equivalent to a viewer's focal length.  But to
shoot
> > >for a specific size anaglyph print, and therein a specific deviation on
> > >paper, I want to predict and set up a shot simply for a particular
> > >deviation on film.  Viewer optics are not otherwise considered.)
> > >
> > >Boris
> >
> > If you already know an on-film deviation that gives you the look you
like,
> > using whatever display mechanism you employ, then you need not be
> concerned
> > about compensating a mismatch between viewer focal length and camera
focal
> > length.
> >
> > I include this ratio of vFL to cFL as a factor in calculating base
because
> > just as sitting in the front row of a 3D theater causes squash not
> > experienced in the middle row, my camera lenses, being of shorter focal
> > length than my viewer lenses cause that same squash.  Increasing the
base
> > proportionately compensates this.
> >
> > I have a closeup 2D picture of my dog's face shot with an 18mm lens (on
a
> > 35mm body).  His nose is nearly the width of his forehead.  Viewed at a
> > distance of ten feet, he looks comical in this picture.  But if you view
> > the print at a distance equal to the camera focal length times the
> > enlargement factor, (about 8 inches for this 11x14 print), his
proportions
> > appear to be normal.
> >
> > Mike
> >
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> > Message: 4
> >    Date: Thu, 23 Nov 2000 08:04:25 -0500
> >    From: Andres Posada O <aposadao@xxxxxxxxxx>
> > Subject: Re: Re: Stereo Base Calculation with a $20.00 Handheld
> >
> >
> >
> > "Michael K. Davis" wrote:
> > >
> > >
> > > The General Solution is an equation.  The author had a reasonable
> > > expectation that users would understand they are *solving for base*,
NOT
> > > solving for deviation, not solving for focal length, not solving for
> near
> > > point or far point, etc.
> > >
> > > Everyone I've read about or spoken to who uses the General Solution,
is
> > > completely content to use it for one purpose - solving for base.  Base
> is
> > > the output.
> > >
> >
> > Michael:
> >    In my HP48G+ I can solve for what ever I want (anybody with the
> > formulas in a computer or the like may obviopusly do it). Doing 3D video
> > I am usually stuck to minimum camera separations, dictated by the camera
> > sizes, that require that I solve for near point, sometimes I need to
> > solve for far point. For example: if I have a minumum camera separation
> > due to camera size of say 165mm, and the nearest object is going to be
> > at 3000mm, then how far may the farthest object be, all this subjected
> > to a MOFD choosen according to CCD size, lens focal length and TASTE.
> > What happens to the near point if I change the focal length position in
> > the cameras zoom lenses? Everything changes if I use 1/3", 1/2", or 3/4"
> > CCDs cameras. MOFD numbers I change according obviously to CCD size, but
> > also I use more "liberal" numbers if all subjects are inside the window,
> > be more conservative with subjects way out of the window and near to the
> > camera. My point is I almost never solve for base.
> >
> >
> > ________________________________________________________________________
> > ________________________________________________________________________
> >
> >
> >
> >
>
>
>
> ________________________________________________________________________
> ________________________________________________________________________
>
>
>
>


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