Color ReversalFilm Processing.- The processing of Kodachrome films (the K- 14 process) is relatively complicated and can be carried out only in licensed laboratories with special equipment.
These are color reversal films. Again, in general, the lower the ISO the finer the grain, and the lower the contrast. Recently, new filmemulsions in the ISO 50 to ISO 100 range have been released.
Transparency or Reversal Film Over Exposure. Loss of highlight detail. Bright areas will 'burn out' leaving just a clear section of film . When it's gone it's gone.
Velvia, however, is a very high contrast and high color saturationfilm, rather unlike most other reversal films. And these facts get lost in that single ISO 50 rating.