. The book of photography; practical, theoretical and applied. i«.lMII(lim(IHH<imjiiJiia»»»Jl»ll liy;. 70b.—fclxAuK Condenser. loi-ms, one with a numerical aperture of1-2 (Fig. 704), the other of 1-4 (Fig. 705), theamount of light collected by the latterbeing proportionately greater. Fig. 706shows the pan-aplanatic condenser ofSwift, 1-0; Fig. 707, a universal con-denser (holoscopic system) by Watson;Fig. 708, an apochromatic condenser ; andFig. 709, an oil-immersion condenser byWatson. All these condensers are suit-able for use with objectives of high mag-nifying powers. An achromatic
. The book of photography; practical, theoretical and applied. i«.lMII(lim(IHH<imjiiJiia»»»Jl»ll liy;. 70b.—fclxAuK Condenser. loi-ms, one with a numerical aperture of1-2 (Fig. 704), the other of 1-4 (Fig. 705), theamount of light collected by the latterbeing proportionately greater. Fig. 706shows the pan-aplanatic condenser ofSwift, 1-0; Fig. 707, a universal con-denser (holoscopic system) by Watson;Fig. 708, an apochromatic condenser ; andFig. 709, an oil-immersion condenser byWatson. All these condensers are suit-able for use with objectives of high mag-nifying powers. An achromatic condenseris much superior to an ordinary condenser,. denser is the same as far as the opticalpart goes, but it is fitted into the sub-stage. These condensers are either non-achromatic, achromatic, or non-achromatic condensers are com-posed of two lenses, while the achromaticand apochromatic condensers are made upof various combinations. A well-knownform of achromatic condenser is theAbbe illuminator, which is made in two Fig. 707.—Watsons Univehsal Condenser. as the light which it transmits is prac-tically free from colour. The oil-immer-sion condenser is used with an oil-im-mersion objective, a drop of oil of cedar- r)3:i wood being placed on the front lens, andthe condenser racked up until it touchesthe under surface of the glass slide onwhich the object is mounted; the lightthen .passes in a straight path from the
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphotography, bookyear
