[tech-3d] Re: Different F.L.s - notice of errata

["Michael K. Davis" <zilch0@xxxxxxxxxxxx>]

Notice of Errata:

I just posted two formulas I use for calculating Stereo Base, as follows:

>Hi David!

[snip]

>Here are the actual formulas I use in the field (with an HP48G+ calculator):
>
>Base=(FL/30*(VFL/FL)*(%MAOFD/100)*(304.8*Near*Far/(Far-Near))*
>                  (1/FL-1/(2*(304.8*Near*Far/(Near+Far))))
>
>Base21=(VFL/FL)*%MAOFD*Near/15

I had whipped out the Base21 equation together from memory (erroneously) -
having cut and paste the Base equation accurately.

Please substitute the following equation for Base21:

Base21=(VFL/FL)*(%MAOFD/100)*(304.8*Near/15)

It now contains two constants I had omitted.

Thanks!

Mike

>
>
>Base:	Stereo Base Separation (mm) for use when the Far:Near ratio is
greater than or equal to 2:1
>
>Base21: Stereo Base Separation (mm) for use when the Far:Near ratio is
less than 2:1
>
>Variables:  
>FL:		Camera Lens Focal Length (mm)
>VFL:		Viewer Lens Focal Length (mm)
>%MAOFD:	Percentage of MAOFD desired (expressed as 70 for 70%, for example)
>Near:		The distance to the Near subject (feet)
>Far:		The distance to the Far subject (feet)
>
>Mike Davis


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