[MF3D.FORUM:532] Re: Exact fl match for paired lenses.

["Bill Glickman" <bglick@xxxxxxxx>]

David

       Thank you  for being my life raft... I have renewed hope!   Your
email led me to believe that if I mounted these chromes properly, I would
not experience the problems I did...if you are right.. I owe ya big time!
Yes, this stuff was expensive.

       Let me explain exactly what I did in the mounting process.... I
mounted the left image for a nice composure.  Then I took the my viewer
apart and put the lens portion over the light box where the two chromes are
being mounted in the frames.  I held the viewer over the chromes at a
distances so that the chromes were clearly in focus.... this simulates
exactly what they look like in the viewer, except I can move them around.  I
then moved the right image around until the center looked fused.  Up and
down was easy, it needed to be the same height as the left image... as for
left and right, there seemed to be only one place where the right chrome
would lay to make the image centers fuse together... if I went further, it
would create double subjects again, the same occurred if I went backwards.
So it seemed that was the only position to put the right chrome... and
everytime I did this, the edges of the scene would have double vision, about
25% at each edge, while the center 50% was fabulous, or WOW.  So I felt this
was the only place the right chrome could go?  No matter where else I moved
it to, it would not create a fused image in the middle?  So where do you
think I went wrong?

Regards
Bill





----- Original Message -----
From: "David Lee" <koganlee@xxxxxxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Tuesday, May 23, 2000 9:26 PM
Subject: [MF3D.FORUM:530] Re: Exact fl match for paired lenses.


> 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
>