P3D Lens Separation and "stereo bight"

["Ray Moxom" <raymoxom@xxxxxxxxxx>]

All of the discussion on lens separation has intrigued me somewhat. Apparent
scale may be a factor in a small number of stereo pics. There is no ideal
separation!

In my opinion most stereo shots work anyway. However, some have distortion
because the subject was too close for the separation and some are relatively
flat (ie they lack "stereo bight") because the nearest element in the
picture was too far away for the lens separation. The acceptable range of
lens separations is quiet large.

Below are some thoughts on lens separation:

If the lens separation is close (eg Iso Duplex and to some extent the RBT
S1) then there is less distortion in close subjects, particularly of people,
and less "stereo bight" (ie stereo effect) if the nearest element in the
picture is further away.

An RBT X2B with 76mm separation can also be used to take low distortion
people shots - just move back and zoom in. It all goes back to the old
closest distance to separation ratio. (Just love those zoom lenses)

As the lens separation increases so does the "stereo bight".

100mm (4in) separation with 35mm lenses can be ideal for most scenic shots
where the nearest object is 3m (10ft) or more away. A similar shot with the
closes object 6m (20ft) away would require at least 150mm (6in) of lens
separation to have sufficient "stereo bight".

The optimal separation for many award winning action slides is often about
150mm - due to distance and focal length of lenses the scale of these pics
are generally well into the acceptable range.

Ray Moxom




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