[MF3D.FORUM:530] Re: Exact fl match for paired lenses.

["David Lee" <koganlee@xxxxxxxxxxxxx>]

Bill,

Let me assure you that 1) you have not made a big mistake (expensive yes,
but not a mistake), and 2) (trust me on this) everything will work out fine
and all your questions will be answered in due time.

Your biggest problem is improper mounting. The "stuff" on the edges will be
masked out either with the proper slide masks, or, if you make prints, by
trimming them. This is what the stereo window is all about. Beginners
usually have a lot of trouble with this. Stereo cameras have this built into
them by moving the film gates slightly farther apart than the lenses. This
can't be done with twin cameras, but you just crop off the outside edges.

----- Original Message -----
From: Bill Glickman <bglick@xxxxxxxx>
To: Medium Format 3D Photography <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Tuesday, May 23, 2000 7:05 PM
Subject: [MF3D.FORUM:526] Re: Exact fl match for paired lenses.


> I tested my paired 80mm Mamiya lenses, and from the outcome, it seems to
> have been an expensive mistake.  I promised I would report in my
results...
>
> The first problem I have is the lenses centers are 5" apart when both
> cameras are mounted next to each other on the slide bar.  This was my
first
> experience shooting at this base seperation.  The results were poor.  When
I
> mounted the chromes I learned why this practice is risky... you can not
> prevent double vision on the side edges.  Although I must admit the center
> looks awesome.

Yes and this is the way it will look when you've mounted it properly.

 But the whole effect is destroyed by the double vision on
> the edges.    I assume this is simply the consequence of having a base
wider
> than it should be..

No, simply improper mounting.

It is possible to get the base in a bit tighter by
> mounting the cameras vertical.... it would be cumbersome and only help a
> bit... it will not accomplish the 65mm base required.
>
This is unnecessary except for really close images.

> Next I took some shots with subjects further in the distance.... I used
John
> B's formula...and I still had the same problem... probably because there
> still was some near subjects in the scene, like grass.

You may have to get rid of the grass, but again the same problem, improper
mounting.


 It increases the Wow
> effect on the far subjects but somehow everything else does not look
right?
> Has anyone else experienced this?
>
Yes, everyone experiences this before they learn how to mount them.


> My conclusion is this.... mounting two cameras side by side on a stereo
bar
> is a very difficult thing to accomplish.

No, it is very simple. I'm sure you've got it right the way you have it.


Not many cameras fit together like
> Greg Erkers do.  So this prevents you from shooting any subjects which are
> near.

NO. Depends on how near we're talking, and how distant the background.


 Moving subjects therefore are limited to greater distances only, due
> to the wider stereo base.   Timing the shutters is very hard to accomplish
> with two cameras, many variables exist in this... however, with a bit of
> fine tuning, this is poosible to get close.... if the subject is not
moving
> too fast, it should be OK.

Yes, I've gotten good sync. on carnival rides with a purely mechanical
shutter.


The wide stereo base does not seem to produce
> images as pleasing as the normal stereo base.... although I did not
> experiment on the Grand Canyon where I am sure it would.

Don't jump to conclusions too quickly.


 Focussing the
> cameras perfectly in sync is also difficult and time consuming.
>
Certainly.

> I also experimented with using a shorter fl lens, 43mm using the 65mm
stereo
> base.  This once again did not create the realism the 80mm lens did?  I
> guess our brain is wondering why the scene is so damn wide???    our eyes
do
> not see like that!
>
> after this experiment, it surprises me that the Gilde MF stereo camera is
> the only new camera on the market today... but at $12k for the camera and
> one pair of stereo lenses, its just a bit pricey for my taste.
>
> Unless someone offers me some great advise, my MF stereo dreams are
drifting
> away.... It seems the best I can do is shoot with one MF camera with one
fl
> lens, and simply move the camera between shots on the stereo bar.  This
> eliminates all motion shots.... even trees blowing in the wind just a bit,
> right?

Absolutely not. You have come to too many erroneous conclusions based mostly
on improper mounting. You may have one of the best rigs for doing stereo
that I have heard of. Do not despair.

>
> Maybe I am making some mistakes or overlooking something major?

Yes and yes.

I am worn
> out and have exhausted my 3d knowledge....  Any input would be helpful, at
> this point, I'll even accept a pat on the back.... and a "Nice try" remark
> :-)

You need someone to sit down with you and explain everything you are seeing.
There are way too many variables for you to understand and certainly too
many for me to explain in this short note.


David Lee