A good helper for Multimedia teaching --document camera
As the key "role" in the multimedia teaching--the document camera is widely used in the teaching.Based on the better convenience for projection teaching,the document camera is popular during the teachers and students. But during the actual use,some teachers are not well-known about the function,or unskilled operation,it makes some problems when the document camera is used.So how make full use of the document camera during the multimedia teaching?
Features and advantages
Document camera/visualizer is an advanced projection and presentation equipment,through the CCD digital camera,the actual objects,models,transparent film,slides,presentations,etc. They can be showed clearly on the display device.Meanwhile,it can save the digital video signal in the computer. It also can connect other devices like projector,AV display monitor,
Interactive whiteboard,to consist of ideal demonstration system,so it is more convenient to be used in the teaching and research.
1.Advantages
So far,most of the document cameras/visual presenters have the definition with at least 400 TV line.The images are always vivid. The document camera always has auxiliary lighting equipment,with automatic white balance adjustment. It can adjust the color of the presentation and film;it can zoom in or zoom out,with auto focus function,black and white color photographing,positive and negative film function;meanwhile,it has a few ports for input and output.So it is more convenient to connect with computer,TV,recorder,DVD,etc.It plays the role of centralized control.If it combines with the projector,this forms a perfect demonstration system. In addition, document camera expands some other functions.For example,if it connects with microscope,the microscopic phenomena can be demonstrated.The document camera has some advantages,it has long life span,small size,low noise,more convenient for use,it can replace slide projector,film projector,etc.
Problems and disadvantages
Just like above,the digital visualizer inherited and developed the advantages of traditional projection devices,to open an advanced application platform for the multimedia teaching.But when we face the new " weapon",most teachers can not make full use of it in the teaching.For instance,some teachers just regards the digital visualizer as video switching tool or simple presentation tool,so it is a waste of this high-grade teaching equipment.
Problems in the teaching
Some teachers are arbitrary with the information and material,don't pay more attention to the processing of teaching information,even they use the visual presenter,but ignore the quality and purpose. Secondly,some teachers can write freely on the traditional blackboard,but when they face the visual presenter,they are a little bit helpless.Actually,from the traditional projector to visual presenter,the biggest advantage is -teachers can write directly and display the contents on the projection screen,this is the display function for the visual presenter,also,in the teaching practice,some teaching software even shows vivid and expressive image,lacking of appropriate teaching features.Some teachers because of adopting ready-made pictures or documents,lacking of theme;when some teachers design the software,the ratio is improper,it can't display completely;and the surface of some software is uneven,to make the projection effect is not ideal.So for these reasons,it requires teachers to make full preparations for the multimedia teaching before the class,then it can generate a multiplier effect.
2.problems during the operation
In a word,the visual presenter is widely used in the multimedia teaching.We should grasp its features and advantages,to make full use of the visual presenter.
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The visual presenter is through the remake method of camera,to achieve the display of pictures,presentation,real objects,etc. But in practice,when teachers make the presentation,some teachers always like to display the whole page under the visual presenter,then it makes the font is very small but can not see. The correct way is partial display or key magnification. In addition,when we display document or picture in big size,the whole content can not display on the screen,at this time,we should rotate the camera,and adjust the focus, then display other parts.but do not move the document or picture. And when we display the real object,we should avoid moving the object as much as possible. Because when the object is in the movement, the camera may occur flickering phenomenon because of lack of enough light. Meanwhile,because the light is weak,so the visual presenter requires more large aperture,and the picture will be blurred easily. Generally speaking, when the object is too bright or too dark,it will occur blurry image or brightness deviation. If the focus doesn't adjust well,it also will make the image flickering.or the contrast is too large, or the color is in distortion,etc. These are because of its own shortcomings of the visual presenter.