[MF3D.FORUM:782] Re: Deviation

[Paul Talbot <ptww@xxxxxxxxx>]

don lopp wrote:
 
> s to focal lengths of lenses I am using. I am at a total loss also as to why
> deviation should be determined by a mathematical formula I thought we had
> eyes and a brain to figure out such things.

You are quite correct.

> According to THE formulu I have
> shot a couple thousand  slides using the wrong deviation

I think this is a common misinterpretation.  The formula only
tells us the *maximum* deviation that an average observer can
comfortably tolerate in a stereo image.  The formula's purpose
is not to tell us exactly how much deviation should be in our
images.  The purpose is to warn us that we're likely to have
trouble if we don't keep the deviation equal to *or less than*
1/30 of the viewing distance (or FL of the viewer)

I think this is one place Bill went wrong with his very strict
adherence to the forumla: he attempted to record the *maximum*
deviation in all cases, and left himself no room for error.

> When I have complained about too much hyper I
> complained usually about weeds in the foreground but I attribute most of the
> blame to the poor view-finders put on most cameras SPUTNIKS, most 35mm
> stereo cameras including RBT probably the worst was the Verascope F 40.

Yup those nasty weeds or often a "single blade of grass" in the
foreground have fouled up many stereo pictures!

Paul Talbot