The American annual of photography . PORTRAIT. L. D. SWEET. 31 with four different pinhole perforations and at different dis-tances from the opening to the plate. The perforations usedwere as follows: 141 microns, 201 microns, 409 microns and545 microns. They have been accurately measured and areapproximately in the ratio of i, 2, 3, 4. (A micron is equal to1/25000 of an inch, but the pinholes need not be measuredthat accurately.) The size as stated can be very convenientlymade by exercising good judgment and directions as very thin sheet brass, or any other thin metal, that canbe
The American annual of photography . PORTRAIT. L. D. SWEET. 31 with four different pinhole perforations and at different dis-tances from the opening to the plate. The perforations usedwere as follows: 141 microns, 201 microns, 409 microns and545 microns. They have been accurately measured and areapproximately in the ratio of i, 2, 3, 4. (A micron is equal to1/25000 of an inch, but the pinholes need not be measuredthat accurately.) The size as stated can be very convenientlymade by exercising good judgment and directions as very thin sheet brass, or any other thin metal, that canbe easily pierced with an average size sewing needle. Pierce ^y?n:v^~K ^^-^iSwe^sr-—. THE TURN IN THE ROAD. Figure 3. the metal with the needle just far enough till the point pro-trudes, this will make an opening of about lOO microns. Tomake the hole a size larger protrude the point slightly beyondthe back of the metal. This will make an opening of about200 microns, etc. Any desired opening that one wishes tomake can be made in this manner. It is however advisablenot to go beyond an opening of 600 microns, due to the lossof definition even for the softness of the photograph. Open-ings should be made upon pieces of metal which are large 32 enough to fit over the opening of the lens board after thelenses have been removed. Having pierced the metal disks with the desired openings,let us turn our attention to the camera. The box type can beused as v^ell as the folding type, and those w^ishing to constructtheir own camera may do so. It is sufficient to say, as spacedoes not permit me to go into the detail of the construction ofthe camera, that there are many books and pamph
Size: 2180px × 1146px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyorktennantandw
