calculate hyperfocal distances

hyperfocals.rb

#!/usr/bin/env ruby

require "optparse"

# default values for command line args
focal_length = 50
apertures = [16, 11, 8, 5.6]
circle_of_confusion = 0.03
use_feet = false

OptionParser.new do |opts|

  opts.on(
    '-f FOCAL_LENGTH',
    '--focal-length=FOCAL_LENGTH',
    Numeric,
    'Lens focal length'
  ) do |value|
    focal_length = value
  end

  opts.on(
    '-a apertures',
    '--aperture apertures',
    Array,
    'Apertures to report for.'
  ) do |values|
    apertures = values.map do |value|
      value.to_f
    end.sort.reverse
  end

  opts.on(
    '-c coc',
    Numeric,
    'Circle of confusion'
  ) do |value|
    circle_of_confusion = value
  end


  opts.on(
    '-F',
    '--feet',
    'Use shitty units.'
  ) do
    use_feet = true
  end

end.parse!

def find_hyperfocal(
      focal_length,
      aperture,
      circle_of_confusion = 0.03
    )
  f_sq = (focal_length * focal_length)

  (f_sq / (aperture * circle_of_confusion)) + focal_length

end

puts "for f = #{focal_length} #{circle_of_confusion}"
apertures.each do |aperture|
  hf = find_hyperfocal(
    focal_length,
    aperture,
    circle_of_confusion
  )./(1000).round(1)
  hf *= 3.281 if use_feet

  hf_2 = (hf / 2).round(1)
  puts "H at #{aperture} is #{hf}. H/2 = #{hf_2}"
end