Pnpiihir Science Monthly 



461 



When the plunger is pressed the action opens 

 the shutter, and when the plunger is re- 

 leased blade returns to its former position 



Home-Made Camera Shutter 



A SHUTTER, which is suitable for a 

 small hand-camera, can be made 

 from odds and ends, and occupies a space 

 23^"xiK"xK'"- The blade, A, is made 

 of thin hard brass, painted dead black, 

 loosely pivoted at the center by a small 

 screw. 



It is ij/g" in diameter, and it has a 

 circular opening, B, for the exposure, %" 

 in diameter. A narrow piece is removed 

 at C, the corners coming into contact with 

 the stop, D, consisting of a small screw. 

 A lever, E, is pivoted to the circular blade 

 at one end and to a second lever, F, at 

 the other, the fulcrum of the latter being 

 a screw, G. The shutter is operated by 

 pressing the little plunger, //, and re- 

 mains open until the plunger is released, 

 when the spring, J, returns the blade to 

 its former position. 



A Useful Trimming Board 



A USEFUL cutting board for trimming 

 photographic prints can be made 

 from a scissors blade and a few odds and 

 ends. The illustration shows the trim- 

 mer complete. The board is i}4" thick 

 and of any convenient area, with part of 

 a flat rule B screwed along the top 

 edge. A strip of steel is screwed along 

 the right hand side, flush with the sur- 

 face. An old scissors blade is secured by 

 means of a screw which forms a pivot 



or fulcrum, the 

 necessary hole 

 having been drill- 

 ed through the 

 end of the blade. 

 It will be seen 

 that the end of 

 the blade has 

 bcenground blunt 

 and the cutting 

 edge straight. 

 When cutting, the 

 blade should be 

 pressed towards 



;zgsi 



The complete trim- 

 ming board for pho- 

 tographic prints made 

 from a scissors blade 



the Steel strip. 



Simple Test of Shutter Speed 



THE following method of testing the 

 speed of a camera shutter may be of 

 interest to photographers who possess a 

 bicycle. Invert the bicycle upon a suit- 

 able support in bright sunshine, and glue 

 a small square of tinfoil to the side rim of 

 one of the wheels. Set up the camera in 

 a convenient position and focus this 

 wheel sharply. Then open the dia- 

 phragm to its largest stop and set the 

 shutter at its lowest speed. The wheel 

 must be revolved at the rate of one revo- 

 lution per second and a shutter exposure 

 should be made while it revolves at that 

 speed. 



The wheel should then be brought to 

 rest and a time exposure given on a 

 second plate. This constitutes a check 

 in the alleged speed of a shutter. 



Using a bicycle, set upside down, to 

 measure shutter speed 



A test can be made several times, and 

 the final results carefully compared and 

 noted. It is necessar\- in all cases to 

 make two exposures to determine the 

 shutter speed. The method is sufficiently 

 accurate for all ordinary purposes and 

 with a pair of dividers to measure the 

 width of the image, there is little oppor- 

 tunity to error. 



