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Optical Instruments. Camera Loupe Telescope (terrestrial and astronomical) Microscope. Camera. f-number. f/# = f’/D f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 f/32 large aperture small aperture
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Optical Instruments Camera Loupe Telescope (terrestrial and astronomical) Microscope
f-number f/# = f’/D f/1 f/1.4 f/2 f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 f/32 large aperture small aperture Amount of light entering is inversely proportional to the square of the f/# 1, 1.96, 4, 7.84, 16, 31.4, 64, 121, 256, 484, 1024
Simple Magnifiers M= ( qL )/ (1 – dL’) q (nearpoint) (-25 cm)
Two special cases: If at infinity M=F/4 (nominal magnification) At “position of distinct vision” M= 1 + (F/4) (maximum angular magnifcation)
Other Types Kellner (achomatized Ramsden) Achromatic doublet for eye lens RKE similar to a Kellner but wider field of view
Abbe or orthoscopic 4 elements (most widely used in quality instruments) Erfle 5 element-Military
Microscope M = -gFoFe/4
M = - f’o/f’e = - Fe/Fo d = f’o + /fe/ = f’o + f’e
M = - f’o/f’e = - Fe/Fo d = f’o - /f’e/ = f’o + f’e