. The book of photography; practical, theoretical and applied. shouldbe understood that the unevenness ofthe surface is more apparent the smallerthe bundle of rays which has to passthrough it. So that if the filter is placedin the diaphragm opening, where thebundle of rays is very small, the uneven-ness is most harmful, whilst as it isremoved from this towards the plate, anydefect becomes less noticeable. Opticallyworked filters are usuallj fitted in a rimand made to screw behind the lens as inFig. 597, but home-made filters should befixed either in contact with the plate or29 immediately befo
. The book of photography; practical, theoretical and applied. shouldbe understood that the unevenness ofthe surface is more apparent the smallerthe bundle of rays which has to passthrough it. So that if the filter is placedin the diaphragm opening, where thebundle of rays is very small, the uneven-ness is most harmful, whilst as it isremoved from this towards the plate, anydefect becomes less noticeable. Opticallyworked filters are usuallj fitted in a rimand made to screw behind the lens as inFig. 597, but home-made filters should befixed either in contact with the plate or29 immediately before it. In small sizecameras the filter may be slipped into thedark slide and focussing done through iton a piece of ground glass placed in theslide. This answers well enough for occa-sional exposures, but for general usethe method t,hown in Fig. 598 is farpreferable. Orthochromatic Plates in LandscapeWork. Valuable as is the use of orthochromaticplates, a great deal too much emphasisis at times laid upon the necessity foremploying them, while claims are made. Fig. 598.—Method of Fixing Screen in Front ofD.\RK Slide. which could never be workers pride themselves uponusing these plates for every descriptionof work, but it will hardly be necessaryto point out to the practical photo-grapher the disadvantages of such a prac-tice. The orthochromatic plate is in thenature of a special appliance, and shouldbe reserved for special use. The inferiorlatitude permissible in the exposure, de-velopment, and gradation of the plates,and the increased precautions necessaryin their manipulation, render them un-suitable for general use, important asthey are in their particular sphere. Forexample, a large number of landscapesthat are brilliantly lighted will photographequally well upon an ordinary dry plate,and there will be scarcely any advantagein the use of orthochromatic plates. Mostexposures made near the middle of theday upon ordinary subjects, such as areattempted by th
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphotography, bookyear
