The Photographic art-journal . directed by the very refined re-resea ches of Mr. Stokes. For portraiture, and all purposes requir-ing great distinctness of outline and rapidi-ty of operation, two achromatic lenses areusually employed. By this arrangementthe focal disrance is diminished ; the imageis much reduced in size, but then it is con-centrated! in every respect, and hence im-proved in all the necessary lenses are, however, still open to theobjection that they produce some distor-tion, which is only to be avoided by great-ly reducing the size of the aperture throughwhich
The Photographic art-journal . directed by the very refined re-resea ches of Mr. Stokes. For portraiture, and all purposes requir-ing great distinctness of outline and rapidi-ty of operation, two achromatic lenses areusually employed. By this arrangementthe focal disrance is diminished ; the imageis much reduced in size, but then it is con-centrated! in every respect, and hence im-proved in all the necessary lenses are, however, still open to theobjection that they produce some distor-tion, which is only to be avoided by great-ly reducing the size of the aperture throughwhich the light falls on ths- lens, and this 248 The Photographic Art-Journal, April, necessarily involves increased sensibility inthe preparations we employ. The distor-tion is not fto the extent which has been represented, bat it may, by careful exami-nation, be discovered in the finest photo-graphic portraits to a greater or less extent. R. Hunt. From the Scientific Daguerrean*PICTURE MAKING.—Nd. IV, BY D. D. T. ©AVIE, THE SENSITIVE COATING. j^HE tone, brilliancy androtundity of sunlight pic-tures depends much uponthis process. The platemay be cleaned, buffed andgalvanized in the most skill-ful manner, yet unless it isproperly coated, the result will be bad,-On the other hand, if the plate is notproperly cleaned, &c, the colors pro-duced upon it by the iudine and bro-mine, are so different from- what theyshould be, that the operator fails of succ ss,and often too without knowing the realcause of his trouble. The peculiar coloring given to the plateby the iodine, depends much upon the con-dition of the last buff, for when the buff isin a good condition, and the plate is inevery way well prepared, the first colorgiven to it by the iodine wi 1 be a beauti-f jl, clear, transparent yellow ; and bycontinuing its exposure to the iodine, thecolor becomes deeper yellow, and finally itchanges to a beautiful soft sky red ; thento purple, and so on through all the varia-tions, the
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectphotogr, bookyear1851
