PhotoCalc

Calculations to compare digital and analog photography

Change only one value and you will get the results immediately!

Start the online calculation here: PhotoCalc online

About the calculation

• Size
  
  • 35 mm KB
    35 mm format with 36 x 24 mm (side-ratio 3:2)
  • 6 x 6 MF
    6 x 6 format with 54 x 54 mm actual picture size (side-ratio 1:1)
  • A3, A4 (B3, B4)
    Paper format following ISO 216 (side-ratio sqrt(2):1, A0 = 1 m²)
  • A,B,C
    Paper format following American National Standard ANSI/ASME Y14.1
  • Legal, Ledger, Letter, Tabloid
    Paper format following American National Standard ANSI X3.151-1987
  • 1 in Sensor, 2/3 in Sensor, ...
    CCD-Sensor size with 16 mm for a 1 in (25.4 mm) sensor
• Focal Length
  If the size of digital sensor is smaller than the size of the analog film, you will get a lens magnification (focal length extension).
  PhotoCalc is calculating the equivalent focal length for the chosen sensor size to the analog 35 mm format (you have to choose '35mm KB' as the analog size!).
  Only a few digital cameras have a sensor as big as the analog 35 mm format ('Full-frame sensor').
  Normally not all of the pixels of a sensor are used ('Effective Size').
• Resolution
  
  • ISO50, ISO100
    The resolution of analog films is given in lines per millimetre (lpmm). The resolution of analog film depends on its luminous intenseness. For the high res Fuji Velvia 50 the manufacturer states 160 lpmm. For the more luminous intense Fuji Sensia 100 the manufacturer states 135 lpmm.
  • Printer, Scanner
    The resolution of digital devices is given in dots per inch (dpi). As examples 300 dpi is given here for a printer and 4000 dpi for a film scanner.
• Size Points - Size Pixel
  The size of a picture in dots or pixel depends
  • on the resolution of the chosen film
  • on the resolution of the chosen printer or scanner and the Colour-Depth
  One MPixel ('Meg Pixel', not 'Mega Pixel'!) has 2^20 pixel (1048576). At a colour-depth of 24 bit (not 'bits'!) one pixel needs three byte (not 'bytes'!) for saving the picture in a file. Are pictures stored compressed (e.g. Jpeg), the resulting file is smaller, caused by the compression. One MByte ('MB' or 'Meg Byte', not 'Mega Byte'!) has 2^20 Byte (1048576).
• Colour-Depth
  Number of bit per pixel for storing the colour information. With only one bit you can only store, whether the point should be black or white (e.g. Fax). With 24 Bit per pixel you can store e.g. the red, green and blue portion as a value from 0 to 255 each.
• Kell factor
  By the digitalisation of a picture with a digital camera information gets lost. This effect don't occurs with an analog camera (if you view the film directly via loupe or projector and don't digitalize it again with a scanner). Thus the sensor of a digital camera needs a higher resolution, than the film of the analog camera. The Kell factor is expressing this and has a constant value of 0,67.
  PhotoCalc is calculation a higher digital resolution always, caused by this. If you don't want this, you can enter 1 for the Kell factor.
• Focal length extension
  Analog and digital focal length is in relation to the picture size. A digital camera with a 2/3 in sensor (8.5 x 6.4 mm = 10.6 mm diagonal) has a picture size, that is 4 times smaller than the picture size of a analog 35 mm camera (36 x 24 mm = 43 mm). A 50 mm lens for the analog camera is like a 200 mm lens for this digital camera.
  Digital cameras with other sensor sizes correspond to other relations.