Guide to bellows extension compensation in old Kodak Photo Guide

I have an old Kodak Photoguide (1970s)--a small compendium of information for ph otographers that includes some useful things for large format. It is small enoug ht to stick in a camera bag and even includes a small gray card. One thing that intrigues me is a scale to be used for figuring exposture compensation needed fo r bellows extension on a 4x5. You place a two inch long object at the plane of f ocus and then hold the scale (which is along the edge of a page) against the gro und glass. You adjust exposure depending on how the 2 inch length on the ground glass falls on the scale in the book. This almost seems too simple. Is there any thing wrong with doing it this way and not using the fairly complicated formula (at least for a head calculation)reported in Simmons Using the View Camera

Tony Galt

Tony, This is perfectly acceptable and accurate method. One of the complicated formulae you are thinking of is for calculating the magnification ratio and applying exposure compensation. That is what the pocket guide doing. The same technique is used for the clever disc calculator you can download. Don't make bellows factor any more complicated than it needs to be.