Mailinglist Archives:
Infrared
Panorama
Photo-3D
Tech-3D
Sell-3D
MF3D
|
|
Notice |
This mailinglist archive is frozen since May 2001, i.e. it will stay online but will not be updated.
|
|
[MF3D.FORUM:1069] Re: Mounting issue
- From: "David W. Kesner" <drdave@xxxxxxxxxx>
- Subject: [MF3D.FORUM:1069] Re: Mounting issue
- Date: Thu, 10 Aug 2000 22:41:15 -0600
Bill Glickman writes:
> Once again, I am confused....
>
> > Just remember that no matter how "square" your two cameras
> > they will always have the problem with the chips.
>
> Why? If the cameras were perfectly square wouldn't the left
> chrome alwasys show more left image every time?
Remember "LLL" the left image shows less on the left side.
The problem is that with two separate cameras there is no
"built-in" window or the window is set at infinity. That means
that the infinity points will be at the window and the entire
scene will be in front of it (coming through it). That is what
all that "excess" image is that you see in one film chip and
not the other. The only way to get rid of it is:
1) to have the camera lenses and film gates offset to provide
a "built-in window"
2) to toe-in the cameras to achive the same thing (sort of)
3) to mask the excess out with the mount (some times this
means going to a small width mount - such as a 6x4.5 portrait)
Think of the spacing like this:
You have an object that is 12 inches wide in front of two
parallel cameras. At the closest the lesnes can be the right
camera "sees" only the right most 11 inches and the left
camera "sees" only the left most 11 inches. When you go to
mount these film chips you will need to have the inner most
edges show the most amount of image, but the extra image in
each is the outside edge.
The confusion may come from the fact that as you move film
chips away from each other in the mount it exposes more of the
inside of each chip which is setting the window closer and
moving the scene behind it. When you move cameras away from
each other you are losing image material from the inside edges.
With my past history of confusing people, I hope you
understand this. I know what I am saying, but may not be
conveying it very well. Perhaps someone else can do a better
job.
> Why would one want to toe in the cameras?
I DO NOT advocate toe in as I don't like the keystone
distortion it can cause. However, done judiciously under the
right circumstance the effect can be hardly noticed.
> I thought perfectly square would be the ultimate, right?
Yes, square, parallel, flush, matched cameras are the
ultimate. Having a built in window just allows more of the
image to be used without cropping.
That's all for now,
David W. Kesner
Boise, Idaho, USA
drdave@xxxxxxxxxx
|