[MF3D.FORUM:1536] Re: folio comments.....

[Paul Talbot <ptww@xxxxxxxxx>]

Bill Glickman wrote:

> I think the 50% correction factor used in Mike Davis's formula
> will correct this, I was to bold in the begining!

Can't disagree with the "too bold" comment.  Shooting for the
maximum deviation in every shot doesn't leave any room for error.
But a 50% correction sounds possibly too conservative.  I'm not sure
I know how the "50%" was figured, however.  Does the "correction"
cut the MAOFD from about 2.7mm to about 1.3mm?  Would it be equivalent
to changing the usual "7 ft to infinity" guideline for a normal stereo
base camera to "14 ft to infinity?"

> I have viewed some of
> Mikes shots, and he used even less correction and his fused very well... so
> I am convinced this is the problem....

What does "even less correction" mean?  Would 30% be an example
of less correction, and would it mean targeting an OFD of about
1.9mm?

> > Do you see cardboard cut out look even though you don't see
> > miniaturization?
> 
>             YES!  Isn't that odd, I notice a lot of cardboard cut out
> things, but I rarely ever see any miniturization.... I still do not have a
> clear understanding of what causes this... do Spud and Rolleidoscope users
> see this too?  I think it is related to stereo base also...???

Someone just asked about cardboard cutout effect over on P3D.  Here
is a reply from DrT:
http://www.pauck.de/archive/mailinglist/photo-3d/mhonarc/msg47491.html

The times that I have seen cardboard cutout effect I felt it
was due to low resolution imaging.  I've seen it in lenticular
prints, and printed stereo pairs.  I can't recall ever seeing
it in a slide, though I might have.  Stereo base can contribute
to the cardboard cutout effect.  How about mailing me an example
of an image in which you see cardboarding?  I'd like to compare
notes.

> > retinal rivalry.

>         NO, I should have explained this one...it has been my experience
> that the wider the base, the more potential for different effects in each
> chrome.  For example, the sun will be cracking through the leaves in the
> left chip at a slightly different location than on the right chip...

Oops, yes you are correct; I'd forgotten about that effect.  Note that
it does also happen in normal base shots, but as you mention it is more
of a problem in wide base shots.

> Also the wider the base, the more risk
> of getting something in one image but not in the other...for example, one
> chip showed a telephone pole from the ground up, the other chip had a
> building blocking the base and only showed it from the top of the building
> up...more retinal rivalry...

That's also a good example...and another one that I've also seen
in images from a normal stereo base shot (the nearest object was
too close to the camera).  This one too is probably more likely
in wide base shots.  But I hesitate on this one, because I wonder
whether the cause might have been an incorrect application of the
stereo base calculation.  For example, perhaps the real "closest
object" in the scene was overlooked, causing the calculated base
to be too large.

Paul Talbot