[MF3D.FORUM:617] Re: Dual Cameras

["Bill Glickman" <bglick@xxxxxxxx>]

Stuart you wrote....


Bill,  I must have 'missed' something in a prior thread regarding this
> obsession with 65mm spacing of the cameras.  It seems that you are trying
to
> maximize your ability to shoot extremely close to your subjects.
> If this is the case then you probably are right.  However, I seldom find
> myself boxed in to requiring this ability in most anything I shoot.  For
the
> most part depending upon my base I just 'accepted' the rough-calculated
> minimum and dealt with it.  It is my opinion that a left and right image
> taken at or approximately the same times is FAR more critical than
worrying
> about capturing such a close near object (3 feet for example).

         I appreciate this feedback.  Maybe I have mistakenly come to this
conclusion.  The chart below shows the reasons why I fell this way.  Below
is John B's formula with an 80mm lens and a constant 2.7mm factor.  As you
can see, the shot selection is very limited with a stereo base a min. of
6.5" and a max. on the stereo bar of 22".   For example, a 10 ft. near would
(which is not that close for a normal lens) allows for a max. of 26 ft. far.
That seems very limiting to me.  And the near and fardistances include
things you do not even want in the scene...This of course assumes I want to
fire both cameras simultaneously...(which I clearly see the benefits of
that)

            The spreadsheet numbers below did not post properly, I took the
first two lines and put them under there proper headings, from there you can
read the rest of them and see exactly what I mean.... I don't seem to think
there is anything wrong with the math.... I am interested in you comments...

> As far as shooting simultaneously, just get used to firing both cameras
with
> cable releases at the same time.  It's close enough!

     Thats good to know, and a bit of relief....

> > I'm willing to guess that if you were to get those two mamiyas close
> together on a flat bar (just have a metal shop make one to your desired
> specs or visit a big hardware store for the parts and do it yourself) and
> use something closer to a 50 or 60 mm lens, and using a dual release
cable,
> that you would find satisfaction in the results.

         I am using a Jaspar engineering 24" stereo bar... the 6.5" min.
inter ocular lens spacing is a result of the camera bodies being too big.
Why do you recommend going to 50 or 60mm, vs. a normal 80mm?



Near and far subject distances below are in feet for 80mm lens and 2.7mm
factor.

                     base
base
Near   Far     Inches                      near         Far      Inches
7         12        6.7                           14       100         6.6
7         10        9.2                           14        80          6.9


8 16 6.4          14 60 7.4
8 14 7.4          14 40 8.7
8 12 9.5          14 35 9.4
8 10 15.9         14 30 10.6
9 20 6.6          14 25 12.8
9 18 7.2           14 19 21.4
9 16 8.2           15 230 6.5
9 14 10.1           15 150 6.8
9 12 14.3          15 100 7.2
10 26 6.5           15 75 7.6
10 23 7.1            15 50 8.7
10 20 8.0           15 35 10.6
10 17 9.7            15 21 21.1
10 14 14.0          16 3000 6.6
10 13 17.3          16 200 7.1
11 35 6.5           16 100 7.7
11 32 6.8          16 75 8.3
11 29 7.1           16 50 9.5
11 26 7.7           16 35 11.9
11 23 8.5           16 30 13.8
11 20 9.8          16 25 17.9
11 17 12.5           16 23 21.2
11 14 20.5          17 5000 7.0
12 47 6.5         17 300 7.3
12 43 6.7           17 100 8.3
12 39 7.0           17 75 8.9
12 35 7.4           17 50 10.4
12 31 7.9            17 25 21.4
12 27 8.7           18 5000 7.4
12 23 10.1         18 300 7.8
12 19 13.1          18 100 8.9
12 15 24.0          18 75 9.6
13 70 6.5            18 50 11.4
13 60 6.7              18 40 13.2
13 50 7.1           18 35 15.0
13 40 7.8           18 29 19.2
13 30 9.3
13 25 10.9
13 20 14.9
13 17 22.2


Regards
Bill G

----- Original Message -----
From: "Stuart Johnson - GCSPHOTO" <GCSPHOTO@xxxxxxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Monday, May 29, 2000 11:59 PM
Subject: [MF3D.FORUM:614] Re: Dual Cameras


> Bill G writes:
>
> >          I have been contemplating this exact issue.  Maybe you can
offer
> me
> > some insight.  I have two M7's now, and my missing link is the inability
> to
> > snap both shots at once when the camera spacing needs to be 65mm.  (Due
to
> > the cameras inability to get this close)  I was wondering when shooting
> > landscapes shots, how critical this is... From what you write above, it
> > sounds like even the slightest leaf or branch being out of place will
play
> > havoc with ones ability to fuse subjects.  I kind of suspected this, but
> > have no base for comparison, since I never had the ability to try this
> both
> > ways.   Do you find that snapping both shots at once is critical some of
> the
> > time, most of time or almost all the time?  Thats what I am trying to
get
> > the feel for....  Any input in this area would be very helpful...
> >
> > I can probably guess this dual firing is very critical...
>
> Bill,  I must have 'missed' something in a prior thread regarding this
> obsession with 65mm spacing of the cameras.  It seems that you are trying
to
> maximize your ability to shoot extremely close to your subjects.
> If this is the case then you probably are right.  However, I seldom find
> myself boxed in to requiring this ability in most anything I shoot.  For
the
> most part depending upon my base I just 'accepted' the rough-calculated
> minimum and dealt with it.  It is my opinion that a left and right image
> taken at or approximately the same times is FAR more critical than
worrying
> about capturing such a close near object (3 feet for example).
>
> As far as shooting simultaneously, just get used to firing both cameras
with
> cable releases at the same time.  It's close enough!  However, your
cameras
> may come ready with an electronic cable release (like the Hasselblads do)
> and thus you can wire two cables together using one button.
>
> I'm willing to guess that if you were to get those two mamiyas close
> together on a flat bar (just have a metal shop make one to your desired
> specs or visit a big hardware store for the parts and do it yourself) and
> use something closer to a 50 or 60 mm lens, and using a dual release
cable,
> that you would find satisfaction in the results.  Why not give it a try?
> Also, you may STILL get some things close to 3 feet by having them 'come
> through the window' in ways that are pleasing and interesting.  Try to
have
> these subjects come from mid-distance and into the middle of the image.
> You'll see some surprising results!
>
> Good luck!
>
>     -Stuart
>