--------------+----+----+----+----+----+----+----+----+----+----+----+----+----+---- Dry series |0,09|0,18|0,26|0,34|0,42|0,50|0,57|0,64|0,71|0,77|0,82|0,87|0,91|0,94 _n_ = 1,00 | | | | | | | | | | | | | | --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+---- Water- | | | | | | | | | | | | | | Immersion |0,12|0,24|0,35|0,46|0,56|0,66|0,76|0,85|0,94|1,02|1,09|1,15|1,20|1,25 _n_ = 1,33 | | | | | | | | | | | | | | --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+---- Homogeneous | | | | | | | | | | | | | | Oil-Immersion |0,14|0,26|0,40|0,52|0,64|0,76|0,87|0,98|1,07|1,16|1,24|1,32|1,38|1,43 _n_ = 1,52 | | | | | | | | | | | | | | --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+---- Monobromide of| | | | | | | | | | | | | | Naphthaline- | | | | | | | | | | | | | | Immersion |0,15|0,29|0,43|0,57|0,70|0,83|0,95|1,07|1,17|1,27|1,36|1,44|1,50|1,56 _n_ = 1,66 | | | | | | | | | | | | | | [Illustration: Photographic objectives with iris diaphragms, f/3.5] ----------------+----+----+----+---- Focal length mm | 64 | 42 | 35 | 24 ----------------+----+----+----+---- Price $ | 20 | 18 | 18 | 18 ----------------+----+----+----+---- =Objective 1b.= It is designed principally for drawing extended sections and large specimens, and consists of two adjustable doublets. By varying their distance, a changeable magnification down to two diameters may be obtained. Price $ 8.-- =Huyghenian Eye-pieces.= ----------------+------+------+------+-------+------+------ Number | 0 | I | II | III | IV | V ----------------+------+------+---------------------------- Focal length mm | 50 | 40 | 35 | 30 | 25 | 20 ----------------+------+------+---------------------------- Price of each eyepiece $ 2.00. The objectives designed for the Edinger apparatus of 64, 42, 35, and 24 mm focal distance have been found to be very useful for a number of purposes and have come into great favor. (see. Dr. Kaiserling: Praktikum der wissenschaftlichen Photographie p. 263). =Achromatic Objectives.=