The page with the formula is here:

Both of the '39 Ford truck pics were done
with the Kodak 2D 8X10 camera and 450mm
APO Skopar lens via Packard shutter.

'39 Ford at Lambertucci's Roma Ranch, Tonopah, Nevada

'39 Ford at Lambertucci's Roma Ranch, Tonopah, Nevada II

The 2 pictures of the Hemingray 45 insulators
and cobbs was done with a 'no name' Bausch &
Lomb brass portrait lens.  It is f5 - f22 and interesting
With a single element up front and a doublet in
The back.  Rather like a Verito, but not near
as soft at f5.

Hemingray 45 Insulators w/ Cobbs from old Tonopah ATT Long Lines f5

Hemingray 45 Insulators w/ Cobbs from old Tonopah ATT Long Lines f22