Advantage of 7p in projection

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Two years ago (Sept. 94) I joined the Detroit Stereographic Society and 
started competing with slides in projection (and in PSA since 1995-96).  
It is after this new experience that I started seeing the advantage of 7p.
My TDC 116 came with the old style carrier wide enough for 7p.  I noticed 
that the 7p images looked better in the screen, compared to 5p, due only 
to their increased size.  

(This might sound like a contradiction to my earlier statement that 5p is 
optimum for projection in square commercial screens, but it is not.  You 
can enlarge a square image the most to fill the screen.  But if you want 
to project a wide image in a square screen you have to reduce it so that 
the wide dimension fits the screen.  By doing this you are not taking 
advantage of the entire screen area.  Most stereo clubs adjust the screen 
to fit 7p slides so they give these slides the advantage of being wider 
when projected with 5p _at the same time_.)

I noticed that the 7p slides were usually rated higher than 5p just 
because of size and found myself mounting slides in 7p mounts even though 
composition-wise the 5p mount was better.  One day I witnessed a great 
stereo slide sequence with clear wonderful 7p images.  At the end the 
narrator said "It was a nice day and I am sure glad I had my Belplasca 
with me".  After that, I wanted to get a Belplasca!

I got my Belplasca around May of '96.  Tried one roll and did not like it!  
For the first time I was seeing regular pictures (remember, all my 7p twin
SLR pictures were hyperstereos... no people at close range) at 7p and I 
had hard time getting used to the wider picture area.  I was tempted to 
mount every picture from this first Belplasca roll in 5p instead of 7p 
mounts.  I did not see a difference in sharpness between the Belplasca 
and my 2.8 Realist.  I felt I was wasting film with the 20 pairs from the 
Belplasca mounted in 5p while I could have 30 Realist pairs.  So, I 
declared "7p in not for me" and went ahead and sold the Belplasca!  
(for a great price too! -- Check old digest!)

A few days later (no, make it hours!!!) I had regretted this.  I felt 
(as Eric G. said in a personal communication) that I did not let the 7p 
grow on me.  My eyes resisted the visual change after being used to seeing 
5p for years.  

A few months down the road I found another Belplasca (now, how many times 
can a person get that lucky to find two Belplascas, *reasonably priced*, 
a few months apart??? It was my lucky year I guess!!!)  I tried a roll 
and this time I was very happy!  This one was a keeper! (I still have it)

To be honest, I still liked my Realist images and preferred them in 
a viewer but the Belplasca with the 7p images had the advantage in 
projection.  And, from time to time, I would get a Belplasca picture 
that looked good in a viewer too!

Now someone might ask:  If the 7p has an advantage over 5p in projection, 
doesn't the full-frame have an advantage over 7p?  Well, no!  IMO, it is 
a matter of personal preference and many people in this list (myself 
included) see the 7p as the optimum proportion.  Full-frame appears too 
stretched for my taste.  Now, if clubs start adjusting their screen for 
full-frame and if more full-frame pairs start showing up competing with 
7p in the same screen then I might change my mind again!  But, at the 
present time, 7p appears to be the king at a club projection level.  

(To be continued with a warning....)


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