Preserving original color transparencies by making duplicates is discussed in detail, including: selection of lenses (macro or other flat-fieldlenses are recommended); selection of devices to hold the slide to be duplicated; selection of film (compared are Kodachrome 25 and Ektachrome 5071 Slide Duplicating Film); light sources, color compensation filters, use of black and white masks to gain shadow detail, pre-flashing to reduce contrast.