Tech Directions - December 2007 - (Page 23)

simple. If the tape loses its stickiness, another can be easily made to replace it (Photo 3). 4. Remove with tongs and swish in the fixer for about two minutes. 5. Rinse well in the rinse water for four minutes and hang to dry. 6. Reload camera and repeat! Preparing the darkroom and chemicals 1. Students should prepare the solutions under the instructor’s guidance in labeled bottles. Commercial stop bath solution is very strong. Water or a vinegar solution will work as well. 2. In the darkroom, set up one cart with a tub of develPhoto 4 oper and a tub of stop bath and another with a tub of fixer and a tub of rinse water. 3. Place a small lamp with the safe red light on the cart with developer and use another small lamp for the 15 W white light. Printing from the negative 1. In the darkroom with your safe light on, make a “sandwich” with a fresh piece of photographic paper as the bottom layer, shiny side up; then the negative, front side up; then the piece of glass to hold it all together. Expose this sandwich with the 15 W white light held three feet above it for 3 seconds. 2. Develop the positive using same process as the negative. The negative can be used over and over to make more prints. Extra hints Loading the camera 1. The camera is loaded in the darkroom with the red safe light on. Remember to close the box of photographic paper after you have loaded the camera and before anyone opens the darkroom door. This must become a habit! 2. The glossy side of the photographic paper is the side that faces the pinhole. It is easy to tell which side is glossy in the red light (Photo 4). 3. Make sure the shutter is closed before leaving the darkroom. ● The pinhole is the most important part of the camera. Thin, sharp edges and a tiny hole give the sharpest images, but if the hole is too small, diffraction effects can be seen. ● You can make tiny to large cameras from matchboxes to refrigerators and larger. A flat film plane will give a different effect. Taking the picture (exposing the photographic paper) 1. The amount of time the shutter needs to be open varies depending on the quality of light, size of pinhole, and focal length. Ours varied from 3 seconds to 20 seconds, depending on how bright the day was. You can find charts on the Internet that will help you calculate f/stop and determine approximate exposure time, but experimentation and practice is needed. 2. Besides exposure time, the most important thing is to keep the camera still. If the shutter will be open more than 2 to 3 seconds, set the camera on something. Holding the camera will result in blurring. 3. The best subjects for a beginner are cityscapes and objects with clear graphic shapes. A large object in the foreground with a long view of a background will give a nice effect, since the background is in focus also. Photo 5—Three different pinhole cameras ● You can make a tripod or holder for the camera in minutes with hot glue and popsicle sticks or wooden dowel rods. ● A really ambitious student can make and load several cameras at once, and carry them outside in a black trash bag. Developing you negative—the most exciting part! 1. Unload the camera in the darkroom with the safe light. 2. Put the paper in the developer and rock the tub so that the chemical moves over the paper. 3. When the image looks good, remove the paper with tongs and swish it in the stop bath for 10 seconds. More About How It Works We see an object when light that is reflected from the object enters our pupil then hits our retina. But, every point on that object is reflecting light in every direction, so the light that enters our eyes from a single point on www.techdirections.com COMMUNICATION 23 http://www.techdirections.com

Table of Contents Feed for the Digital Edition of Tech Directions - December 2007

Tech Directions - December 2007 Technically Speaking Contents Direct from Washington The News Report Technology Today Technology's Past Mastering Computers Is This Op-Amp Any Good? Lab-Built Checker Removes All Doubt Here Comes the Sun! Residential Solar Systems Add Up to Savings Pinhole Cameras—For Science, Art, and Fun! Poster Project Maps Out Design Process Gifts for Geeks E-gallery More than Fun

Tech Directions - December 2007

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