EMO-Optik Arthur Seibert Octoscop L EMO-Optik Arthur Seibert Octoscop L Another unique optical instrument from EMO-Optik Arthur Seibert EMO Wetzlar is Octoscop L Octoscop is an 'Universal Vest-pocket Magnifier" . It consists of four loupes of 2x, 4x 10x and 18x. These four loupes can be combined to make 6x 14x 20 x and 28x for a total of eight magnifications, hence the name "Octoscop" ---- eight loupes ( 2x, 4x, 6x, 10x,14x, 20x, and 28x )in one package The four loupes are : ( 2x plano-convex ( 4x loupe plano convex () 10x loupe cemented achromat loupe ()) 18x three element loupe 4x loupe and 18x loupe are arranged in the form of an 8 butterfly 2X LOUPE AND 18X loupe are also arranged in another pair of 8 butterfly These two pairs of 8 shape primary loupes can be combined to make (14x 20x) and (6x 28x) compound loupes. In the following table: same colored pairs belongs to one butterfly (2x 10x) and (4x 18x) are primary pairs (6x 28x), (14x 20x) are compound loupe pairs from the two primaries. 2x 10x 4x 6x 14x 18x 20x 28x Octoscop specification Primary loupes : 2x plano convex 4x plano convex 10x cemented achromat doublet 18x three element in two group; cemented doublet + plano-convex Compound loupes 6x = 2x and 4x 28x = 10x and 18x 14x = 4x and 10x 28x = 10x and 18x Dimension length ; 78mm width: 30mm Weight : 30 g Packaging : Black plastic box 4x 9x13cm; Genuine black leather case Neck strap Made in Germany Application of Octoscop EMO-Optik Seibert Octoscop is the most versatile combination magnifier offering eight different magnifications. The rule of thumb for viewing slide/negative with correct perspective is magnification= 250/focal_length of lens(in mm). Therefore, different magnifications of Octoscop is suitable for viewing chrome transparency or negatives for all kinds of format, from large format, medium format, 35mm to subminiature photography Magnification Combination Composition Best for viewing slide/negative of 2x plano convex f=120mm lens 4x plano convex f=60mm: Leitz 60mm/2.8 Macro-Elmarit 6x 2x + 4x 2 element 2 group f=35mm to 50mm ;Minoxar/Minotar 10x cemented achromat doublet f= 25mm-- 28mm lens 14x 4x + 10x 3 element 2 group 18x three element in two group; cemented doublet + plano-convex COMPLAN/MINOX 15mm lens 20x 2x + 18x 4 element 3 group fine detail 28x 10x + 18x 5 element 4 group fine detail 6x loupe is particularly suitable to view slide made from camera lens with focal length from 35mm to 50mm, resulting in realistic perspective. Similarly, using 18x to view Minox 8x11 slide or negative resulting in realistic perspective. Further, if proper loupe with right magnification is used, the image has a 3-D feel, because of monocular vision in viewing slide/negative with loupe.