Slide projectors are used for the project. One contains a glass plate with a light source from below, that the image in transparency through a lens of an arm with a mirror screen. The films are polyester film through a standard A4 size, which allows light.
Overhead projectors are simple to use and were the first to be used for business and classroom presentations. This was before the arrival of data and video projectors. The projectorcan be set to 10 seconds, the arm can be folded for easy transport and weighs about 14 kg. The resolution may be in the range of 4000 lumens. The OHP is equipped with accessories such as a portable stand so that the projector in the middle class, a folding screen, extension cords of different lengths, and sockets can be placed.
The rental prices usually range from $ 30 to $ 50 per day, $ 100 for a week and $ 200 for a month. Most lecture halls have overheadinstalled. Advances in data projection for CD, DVD and laptop computers have reduced the demand for OHP.
Use of projectors has declined with the flashy presentations of PowerPoint. However, they are sometimes used in universities, classrooms for lessons and training. Of data projectors are preferred, because they are simple and do not require computers for input. The film may, during the same conference, which makes it versatile to be changed. The disadvantage is thatOHP is fragile and cumbersome. In addition, care should be taken that the film is unclear. For example, photocopied pages of textbooks in a bad light on the screen.
Some of the major airlines branded projectors are 3M, Bell & Howell, Dukane and high lumens. Special features such as built-in lamps and image magnifiers add higher rents.
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