Bracketing
an exposure by f-stop takes just a tweak of the lens aperture ring;
bracketing with time is more difficult because it can involve awkward
fractions. But the latter is an important option when using a wider
lens aperture would reduce needed depth of field, which is why we
offer the Bracket Finder (BF1), a precision-made dial calculator.
To use it,
you just align an arrow on the inner dial with your metered exposure
time. The adjacent sixth-stop values will then line up with corrected
times on the outer dial. The Bracket Finder also indicates the number
of "pops" needed for bracketing in open-flash photography,
as well as darkroom printing time adjustments and relative film
speeds. Full instructions for each application are printed on the
back of the dial itself. substitutes!
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Bracket Finder improves exposure control by indicating
f-stop equivalents for bracketing with exposure time.
• Determines
the number of "pops" required for specific
exposure brackets with open-flash technique; equates
time changes with "stops" of light for greater
consistency in printing; and indicates relative ISO
ratings in stops to aid film choice.
Exposure bracket calculator
made of two rotating calibrated plastic disks (BF-1).
Outer dial is four inches in diameter and marked in
seconds; inner dial is 31/4 inches in diameter, and
marked in eighths of stops. Values on outer dial are
convertible to film speed (ISO) numbers or multiple
flash pops.
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