Re: More thoughts on formats

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

->> Why do most 5-P format cameras lack borders between frames? 

->Basically it's because they're trying to maximize image size.
->5P at 4.75 mm per perf is 23.75 mm.  I think the mask is
->nominally 21.4 mm wide.  So there's precious little extra.
->They'd have to be very precise in their advance to give you
->a border and then there would be no room to make adjustments.
->You might get unhappy one day when, if you had had just a little 
->more image on one side, you could have gotten rid of something 
->nahstie on the other side.

> I always thought that the 5-P format was chosen because you could get
> two frames in between a pair without having an excessive separation...

I've always thought that too.  If I've said something that conflicted 
with that I apologize.

->What would really be nice would be if the 5P cameras were
->very precise in their advances so that there wouldn't be any 
->image overlap.  Then nothing would be wasted.

> The film advance IS precise, BUT the Realist has focal plane focussing.
> As the film plate moves to and fro it plays havoc with the chip spacing.

I've never actually worked with a Realist.  All other 5P cameras I've worked 
with have imprecise advance though this is very likely due to bad karma.  8-)

->66.5 is 
->much closer to the average human eye spacing than 71.25.  So
->5P cameras are slightly hyper and therefore make things look 
->slightly smaller than life size.  This also means the depth 
->cues are slightly stronger in the 5P.

> Is the average human eye spacing 71.25mm? I thought it was smaller -
> about 65mm, so close to the Belplasca spacing (or was that what you
> meant to say?)

As far as I know it's 65 mm.  Sorry if I said something that could be 
construed as opposing that.

John B


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