[MF3D.FORUM:536] Re: Exact fl match for paired lenses.

["Bill Glickman" <bglick@xxxxxxxx>]

Paul

> > 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.
>
> I assume here you are talking about the doubling of the window
> frames (inability to fuse the stereo window) caused by the stereo
> window not being set properly.  True?  Or perhaps there is too
> much non-stereo information at the edges?

        The left edge and the right edge have tremendous double vision, and
they are not even close like the ones you saw at my house, they are pitiful.
It is like there is two edges on the left and two on the right!

> > Although I must admit the center looks awesome.
>
> That's a good start!  :-)

      Yeah, I agree, I was totaly taken back by how much more feeling of
depth one gets when the seperation increases.  But that creates too much to
overcome on the edges...


> > But the whole effect is destroyed by the double vision on
> > the edges.
>
> Imagine...just one week ago this same guy would never have
> even noticed a window problem like this!  That's incredibly
> fast progress!  :-)

       I blame it all on you Paul, thats what happens when you show off your
best images!  Now look at me  :-(

>
> > I assume this is simply the consequence of having a base wider
> > than it should be..
>
> Maybe.  But aren't you shooting 6x7?  There should be plenty of
> room to set the stereo window in the RMM 50x50 mounts with 6x7
> chromes.

        I can crop a lot with 6x7... but it did not seem to matter, where
ever I put them they failed, except one place... that is what caused me
grief...


>
> > 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.
>
> 65mm is not the only useful stereo base...

      But for close subjects it sure seems to be the one that works best!  I
agree as per John B's formula, as the there is nothing near and the rest of
the scene is at infinity the wider bases pay off.


> > It increases the Wow
> > effect on the far subjects but somehow everything else does not look
right?
> > Has anyone else experienced this?
>
> You are probably experiencing the miniturization or Lilliputism
> effect we discussed.  That and some problems fusing the whole
> scene, perhaps.

       Paul, that did not happen at all, nothing looked smaller or out of
proportion!  The center was perfect and really felt the depth!  Was this
what you meant?

> > Moving subjects therefore are limited to greater distances only, due
> > to the wider stereo base.
>
> True.

       This part really bothers me.... I need to explore the mirror
arrangement, it may be my only hope to overcome this!  At first I thought
your 1930's Rolleidoscope was overpriced at $2500, now I think its a real
bargain!!!  :-)


> > 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.
>
> Agree.  Your situation is complicated by having one mechanical
> and one electronic release camera body.  (Anyone have any tips
> on dealing with that?)

       If I can solve the other problems, I can fix this problem with
getting a new M7II body so they are both electronic.  I can sell my older
one on ebay for not much loss.  So this issue is not high on priority list!


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

> Were you trying to focus on a particular object in the scene?
> Focus in stereo is usually done by hyperfocal settings, due
> to needing sharpness throughout the z-axis.  If your lenses
> have good focus synch, you should be able to set them to the
> same distance reading and fire away.

       I checked my DOF charts, and figured where I needed to focus to get
everything in focus, then found something at that distance and maunaly
focussed each camera.  This is doable, just cumbersome... the least of my
complaints...

> > 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!
>
> Anytime you vary the stereobase from 65mm and use non-matched
> shooting and viewing FLs, you will be impinging on the realism
> of the reconstructed scene.

       Yes, I can see that now, loud and clear....



> Try a Rolleidoscop.  :-)

      I knew that was coming.... I have so much invested in this now, I want
to explore this to the end before throwing in the towel... and remember, I
am very very happy with images I shoot with one M7 camera on the slide bar.
As long as the subject is not moving, the images are fabulous!
Unfortuatnely most subjects in nature I want to shoot will have some motion,
even if its just the trees swaying a bit.


> How about some encouragement from the cheerleaders?  Let's all
> chant now...
>   Go, Bill, Go!  Go, Bill, Go!

         Ahhhh now I feel better, thanks Paul!

>
> Hang in there, Bill.  We'll figure something out!

         You are such a great bunch of guys, I hope someday I can mak more
contributions vs. doing all the asking.... I offer a lot on the LF forum,
but MF stereo is so specialized, so few people can offer advise, so I do
really appreciate the time many of you take to work with us newbies!   And
in this type of forum its so helpful since so many of us read the emails and
pick up tips with out ever contributing...

Regards
Bill G