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Camera Selection and Testing. Resolution. What resolution is needed? Application dependant Footwear and tire impressions. Camera Resolution. Film or Sensor Lens Final image. Film or Sensor Size. Physical size of film or sensor Resolution relative to object size
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Resolution • What resolution is needed? • Application dependant • Footwear and tire impressions
Camera Resolution • Film or Sensor • Lens • Final image
Film or Sensor Size • Physical size of film or sensor • Resolution relative to object size • Larger film or sensor increases final resolution. • 35mm film generally accepted as having sufficient resolution for Footwear impression documentation.
Digital Camera Sensors • Pixel Density • Light sensitivity • Physical size
Lenses • Quality of manufacture • Focal length
Final image • Print size • Printer capability
Testing • Line resolution • Edmunds Scientific Resolution chart • 24X36 inch poster • Multiple USAF resolution targets • Center target used to determine line pairs resolved per millimeter
Cameras • Canon EOS Elan 35mm film • Canon EOS 1Ds Mark 2 • Sensor size same as 35mm film • 16.7 MP sensor • Canon EOS 20D • Sensor smaller than 35mm film (1.6X) • 8.2 MP sensor
Lenses • Canon EF 24-85mm • Canon EFS 17-85mm (20D only) • Canon EF 24-105mm • 50mm focal length used for all testing • EOS 20D set at 50mm equivalent
Final Images • Printed by photo processing lab • Center target printed 65% of natural size due to limitations of processing lab
Procedure • Edges poster filled frame (24X36 inches) • 11X17 inch area also captured with EOS 20D • All digital images captured with jpeg format • Four ISO settings, three file sizes, and three compression settings used with EOS 1Ds Mark 2 • One ISO setting, three file sizes, and one compression setting used with EOS 20D
Procedure (cont.) • 35mm film results compared to EOS 1Ds Mark 2 results. • EOS 1Ds results compared to EOS 20D results. • Lens comparison images of 11X17 poster area captured with both EOS 1Ds and EOS 20D.
Results • EOS 1Ds met or exceeded Film at several settings • EOS 20D met EOS 1Ds resolution at its highest setting for the 11X17 poster area • Different lenses will affect the resolution of captured images