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Focus
The Case for Cameras
2/28/2006
No enthusiasm for document or PTZ cameras? Maybe you’ve been looking at the wrong angles.
When discussing the technology needs of a classroom, be careful about mentioning the word “camera”—it always requires further qualification. To non-technical people, “camera” can mean any type of electronic device that isn’t a computer, and which resides in a classroom. But here are some thoughts on two specific types of legitimate cameras increasingly found in today’s classrooms:
Document Cameras
The concept is simple: This is a camera that looks down at whatever you put under it; the video image is then sent to a monitor, codec, and/or projector for viewing by a larger group. Sounds like a godsend, right? Yet, educational users are mixed on their assessment of the usefulness of document cameras. Some point to the prevalence of computer-based presentations and cite low actual usage of existing document cameras to justify not placing them in new or renovated classrooms. But others like the flexibility of being able to display nearly anything to students both local and remote, and the ability to replace the venerable overhead projector as a convenient tool for annotation and real-time, pen-based interaction. These are the folks who want document cameras in every room.
Two categories. All current document cameras fall into one of two general categories: those with low resolution output (composite and/or S-video) and those with high-resolution output (1024x768 or higher). Many negative feelings people have about the use of document cameras stem from the use of low-resolution devices, which often deliver fuzzy, incomprehensible text when viewed on a large screen or through a Codec.
Key Considerations
When evaluating document cameras, here’s what you should be considering:
Resolution. Ideally, document camera resolution should match the native resolution of your other display device(s). Having an SXGA (1280x1024) signal going to your XGA (1024x768) projector is no better than having an XGA signal from the document camera. Unless an application is video-only—with no high resolution display anywhere in the system (and unlikely to ever be added)—I normally recommend some type of high-resolution document camera over the low-resolution types. The cost difference is not very much, and the difference in image quality is immediately apparent.
Refresh rate. Not especially important when looking at static images (such as a document), refresh rate is very important if the instructor will be annotating on the page (as in the overhead projector replacement scenario). The specified frame rate refers to the number of times per second the screen is updated. Units with a low rate (less than 20 fps) will prove unsatisfactory for instructors who like to annotate or frequently move the object underneath the camera. For this style of document camera usage, a refresh rate of 20 fps or greater is desirable, and 30 fps is considered ideal.
Zoom lens. Often touted as an upsell by manufacturers, this specification matters much less than you may initially assume. If the instructor needs to zoom in on small details of a document or a 3D object, then the greater the zoom ratio, the better. But if the camera is being used primarily to present text or graphics in the context of a full-size page, then the zoom ratio is largely irrelevant.
Form factor. Document cameras come in all shapes, sizes, and mounting locations—from the portable and the full-size, to the ceiling-mounted. Three ceiling-mounted options are especially worthy of mention: The Wolfvision (www.wolfvision.com) VZ-C12 ($12,960 MSRP) has a 16x optical zoom, lens and projects a light field onto the flat surface below, both to provide added illumination for the subject and to indicate to the user the extent of the zoom (the light is synchronized with the zoom lens). The Elmo (www.elmousa.com) HV-C1000XG ($9,995 MSRP) has a 12x optical zoom lens and a downward-shining light, but the light is not controlled or synced to the lens, which can create glare issues at a podium. The Vaddio (www.vaddio.com) CeilingVIEW Mega-Pro Visualizer ($6,995 MSRP) d'es not offer a supplemental light, but d'es have a trigger-able laser dot for aiming its 12x optical zoom lens, based on a native 16:9 3-CCD Sony camera. Plenum above-ceiling housings for a clean installed look (one of the main reasons for using ceiling-mounted document cameras in fixed installations) are available from Display Devices (www.displaydevices.com) for the WolfVision camera, and from Elmo for its own camera, and the Vaddio camera comes in its own plenum-rated back-can.
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