The artistic side of photography in theory and practice . bathed in isocyanin, is certainly moresensitive to green, yellow, and red ; but even herethe violets and ultra-violet predominate ; and thepanchromatic plate suffers from the great disadvantagethat it is not easily developed by any dark-room light—in fact, it is best developed by time development. Now, it will be noticed that, although the ortho-chromatic plate is rendered sensitive to green andthe panchromatic plate to the whole of the spectrum,both these plates are overwhelmingly sensitive to thosechemical rays which do not affect the
The artistic side of photography in theory and practice . bathed in isocyanin, is certainly moresensitive to green, yellow, and red ; but even herethe violets and ultra-violet predominate ; and thepanchromatic plate suffers from the great disadvantagethat it is not easily developed by any dark-room light—in fact, it is best developed by time development. Now, it will be noticed that, although the ortho-chromatic plate is rendered sensitive to green andthe panchromatic plate to the whole of the spectrum,both these plates are overwhelmingly sensitive to thosechemical rays which do not affect the human defect is remedied by placing a screen of brighttransparent yellow close to the lens. The yellowscreen allows the greens, yellows, and reds to passthrough unchecked, whilst it stops the ultra-violet,and reduces the intensity of the blue and violet. The following diagram shows the result of using the screen ULTRA VIOLET-VIOLET BLUE —Blue Green — GREEN - Orange Yellow — RED — tfUMAN ICHKOMAIIC -SCREEN. + PANCHROMATIC +SCSSE5. 267 The Artistic Side of Photography jfe It is evident from this diagram that an ortho-chromatic plate with a screen is sensitive to both greenand yellow, whilst it is only a little too sensitive toblue—the red is not rendered. The panchromaticplate with the screen sees colours in much the sameratio as the human vision. In other words, although the orthochromatic platewith a screen shows a nasty little gap in the bluish-green—somewhere about the colour of the pine-needles—when it is exposed behind a screen theplate is sensitive to the general colours of both land-scape and seascape. Without a screen, the ortho-chromatic takes the place of the ordinary plate, andgives the same simplicity of tone rendering ; andsince this plate is blind to red, it can safely be developedby a good red light. The panchromatic plate is invaluable in any sub-ject where red predominates ; it gives very delic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphotogr, bookyear1910
