Angle of view is the
most accurate way for comparing lenses and formats. The Focal Length Equivalent
Chart is to aid us with a very simple comparison to a format that 99% of us
have graduated from. The 35mm comparisons are very close. The angle of view was
measured from the actual exposed aria of the negative whenever possible. This
is why a 6x12 and a 4x5 have the same position. (120mm is the actual exposed
with of a Fidelity cut film holder)
Please note that
while a lens may cover the horizontal angle of view given in the chart,
coverage is necessary for the diagonal angle of view. These charts are intended
to aid in lens focal length selections. The coverage of the lens and the
movements available with any given lens is an entirely different matter that I
hope to address in the future.
Thanks for looking.