[photo-3d] Quiz #2 revisited

["Chuck" <cfholzner@xxxxxxxx>]

> Subject: Re: Quiz#2 - its all in the film travel
>
> BP wrote
> > Turning the camera upside-down changes the film travel direction from
L-R to  R-L. This is the difference.
>
> Oh, no!  Now more people are being sucked into Cliff's Evil Looking-Glass
> Vortex of Doom!  As his first witless victim, I feel responsible.
>
> Look, everyone, the only film travel that matters is the trip it takes on
the boat.  If you had a perfectly symmetrical pinhole camera with a square
> of film in it, shot, reloaded while the boat moved, and shot again, it
would not matter if you turned the camera right side up, upside down or
sideways - you would have the same two image to work with at the end.
> Having it all in one camera that "changes" the film by itself has no
effect on that end situation.
>
> Oh Mighty Chuck!  Save us miserable wretches who have fallen into darkness
> and error!
--------------------------
Hello, Chuck here.

When I first read the "film travel" one I though someone was making a joke.
I was wrong.

I don’t know that I can say it any better then Bruce just did.  I don’t know
that I can add anything at all but here goes.

The image is made by the lens with light.  Light coming from a scene is
focused on a plain behind the lens.  This image is reversed top to bottom,
left to right, upper left to lower right, lower left to upper right etc.
The lens is round and can be rotated around a line coming straight out the
front without changing the image.  Lenses are stupid; they don’t know up
from down, left from right, which way the film came in or if there is film
in at all.  They don’t know the time of day or how many pictured it has
helped to make or if the last picture was supposed to be the right or left
image. All it does is bend the light to make images that are reversed from
the scene.

It doesn’t matter how the film got there.  Whether it entered stage right or
stage left or fell in from the top or came up from below.  The lens cannot
remember that far back and so, doesn’t care.  It only matters that film is
there, not already exposed, and that it is not still moving relative to the
camera.  Most cameras are interlocked so you can’t open the shutter while
winding the film, so we are dealing with film that is staying put.

Since the image is always up side down and backward to the scene, rotating
the camera does not rotate the image, however, it does rotate the film.
Turning the camera up side down will turn the film up side down from it’s
normal position relative to earth.  Taking a picture in this position will
expose the image in a position up side down relative to images exposed when
the camera was right side up.  The ONLY difference will be that it is up
side down relative to the images that were taken normally.  When the chips
are cut apart and arranged right side up there will be nothing different to
indicate that the one was taken with the camera inverted except the writing
and numbers on the edge of the film.  When viewed, it will look just like it
was taken with the camera right side up.

If we could reverse the depth by winding the film in a different direction,
we would be doing it.  It would greatly simplify mounting medium format by
not requiring us to cut the chips apart and then reverse and re-align them.
Everyone would be shooting his Sputnik up side down.  Someone would have
designed a camera that moved the film the other way to take advantage of it.
This just doesn’t happen.  The lens will do its’ thing no matter how the
film got there.

Dr. T, who started this tread, did not turn his camera up side down when
taking his Manhattan shots, at least he didn’t say he did.  He took a series
of pairs and found one pair out of the lot that put the clouds to the rear.
He attributed the good pair to the wind stopping long enough to take the
shots.  I would be more inclined to believe the wind shifted or the boat
turned but I wasn’t there.  It would not have to be a 180 degree turn.

If you still believe that the direction the film winds will reverse stereo
depth in parts of the image tell me what differences to look for in my
Realist 45 which winds from right to left compared to all my other cameras
that wind left to right.  The chips come off the roll in a different order
but when mounted, they look normal to me.

I want my SWT.

Chuck



 

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