Photo Lab Manual (PDF) - Richland College

Flash:Electronic flash can be used with a visually opaque Kodak 88A, 87 or 87C gelatin filterplaced over the flash head. The filter on the flash will have a dim red glow when fired,but no apparent flash of light, and no filter is required on the camera lens itself using thismethod. Exposure using this method should be arrived at by trial and error. When using the87 or 88A filter, ISO 25, or 87C, ISO 10 should be used as a starting point.Focusing:Infrared rays focus at a different plane than visible light. Most lenses for SLR cameras havean infrared focusing index mark engraved on the lens barrel. Focus normally, then shift thelens barrel to this index mark. Stopping the lens down to f/8 or higher will result in greaterdepth of field, thus rendering the infrared image sharp enough for most purposes.60