NAME

Photography::DX - Encode/decode DX film codes

VERSION

version 0.02

SYNOPSIS

 use Photography::DX;
 
 my $film = Photography::DX->new(
   speed     => 100,
   length    => 36,
   tolerance => 2,
 );
 
 # print out the layout of contacts
 # on the roll of film as a series
 # of 1s and 0s:
 print $film->contacts_row_1, "\n";
 print $film->contacts_row_2, "\n";

DESCRIPTION

This class represents a roll of 35mm film, and allows you to compute the DX encoding contacts used by film cameras that automatically detect film speed, the number of exposures and the exposure tolerance of the film (most cameras actually use only the film speed for the DX encoding).

CONSTRUCTOR

 my $film = Photography::DX->new;

In addition the attributes documented below you may pass into the constructor:

contacts_row_1

The first row of contacts on the roll of film. The speed will be computed from this value.

contacts_row_2

The second row of contacts on the roll of film. The length and tolerance will be computed from this value.

ATTRIBUTES

speed

The film speed. Must be a legal ISO arithmetic value between 25 and 5000. Defaults to ISO 100.

Special values 1-8 denote "custom" values.

length

The length of the film in 32x24mm exposures. Must be one of undef (denotes "other"), 12, 20, 24, 36, 48, 60, 72.

tolerance

The exposure latitude of the film. Must be one of:

0.5 for ±0.5 stop
1 for ±1 stop
2 for +2 to -1 stops
3 for +3 to -1 stops

METHODS

contacts

 my($row1, $row2) = $film->contacts;

Returns both rows of contacts.

contacts_row_1

Returns the contact layout as a string of 1s and 0s for the first row of electrical contacts. 1 represents a metal contact, 0 represents the lack of metal.

contacts_row_2

Returns the contact layout as a string of 1s and 0s for the second row of electrical contacts. 1 represents a metal contact, 0 represents the lack of metal.

is_custom_speed

Returns true if the film speed is a custom film speed.

logarithmic_speed

Returns the ISO logarithmic scale speed of the film (also known as DIN).

CAVEATS

In digital photography, DX also refers to Nikon's crop sensor format DSLRs.

DX encoding was introduced in 1980, well after the development of 35mm film and so many types of film do not include DX codes.

This module uses features in and requires Perl 5.22.

SEE ALSO

Photography::EV
http://en.wikipedia.org/wiki/DX_encoding

AUTHOR

Graham Ollis <plicease@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2015 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.