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ScoMIS - Digital Projectors created by Curriculum Software Support Choosing a Digital Projector The following tips have been drawn from advice sheets made available by the leading companies involved in educational use of ICT. For education, there are 6 main factors that can be considered critical when selecting the right projector. They are weight, brightness, resolution, contrast ratio, budget and cost of ownership. BRIGHTNESS The light output from the projector is commonly expressed in ANSI lumens (American National Standards Institute measurement of candle power). Your choice should be determined by the environment in which the projector will be used. For example, in a darkened room a brightness of around 1000 ANSI lumens will produce an acceptable SVGA image. However, where daylight conditions prevail a projector with a rating of 1000 ANSI lumens and upwards should be selected. Often, the type and size of screen used can greatly enhance the apparent brightness of a presentation but as a general rule the greater the projector distance and the lighter the environment, the greater the required brightness. It is also important to note that a lamp slightly reduces in brightness during its life. WEIGHT Data projectors are getting smaller and smaller and while this is useful within a commercial environment the opposite is often true within Education. Firstly, the smaller the projector is the less space exists around the lamp, which in turn reduces the airflow available for cooling and extending bulb life. Secondly, the smaller the projector is the less it is likely to be able to withstand regular daily, instead expecting to be used perhaps only for an hour at a time a couple of times per week. Thirdly, the smaller the projector is the more likely it is to be targeted by thieves, particularly where the usage is as a mobile device rather than mounted on a ceiling. RESOLUTION This relates to picture clarity and is expressed as the number of pixels displayed. The following termsare applied: pixel width 640 800 1024 lines 480 600 768. VGA SVGA XGA The higher the resolution, the crisper the projected image will be (subject to distance). SVGA and XGA are the current common formats. Under normal presentation circumstances, SVGA will be acceptable, but for fine line drawings or spreadsheets, XGA is advised. Data projectors have a single true resolution ScoMIS - Digital Projectors created by Curriculum Software Support but may accommodate other resolutions using in-built compression or expansion technology. It is best practice to match your projector with the native resolution of your computer or other input source. CONTRAST RATIO This is an indication of the dynamic range of a projector. Very simply, low contrast ratios offer poorer image distinction than high ratios, which is very important for clarity of text. This ratio, in combination with the brightness, resolution and projection distance will determine the image quality. Ratios of 200:1 and above yield good performance for most applications, but if projecting over long distances or in daylight conditions opt for the highest ratio you can. BUDGET Budget is often the decisive factor in choosing the projector. In general, you get what you pay for – the higher the specification the more it will cost. Ultimately the amount you spend on a projection system should reflect its importance to your organisation. COST OF OWNERSHIP Lamp life, warranty types and warranty length. There are three typical warranty offers available and it is important to establish which comes with your selected projector as it can make a significant difference to the service level and classroom availability: 1. 'Return to base' Return to base warranties are the most basic and the most common. In the event of a problem, the projector will need to be returned to the manufacturer’s service centre. It will be repaired, usually within two to three weeks, and then sent back to you 2. 'Repair-or-replace' In the event of a problem with your projector, the manufacturer will in the first instance attempt to resolve the problem over the phone. If it cannot be resolved, a manufacturer’s technician will visit you on-site the next working day. If the projector cannot be repaired onsite a replacement will be left while the faulty projector is repaired. 3. 'Swap-out' If you have a projector problem that cannot be resolved over the phone, a replacement projector will be despatched to you and your projector will be collected. You retain the replacement projector. This is nearly always carried out on a next working day basis, although sometimes it is subject to stock of replacement projectors of a similar specification. 4.Length of warranty ScoMIS - Digital Projectors created by Curriculum Software Support An average warranty is two years, although as projectors become more reliable, more and more manufacturers are offering three-year warranties. Warranty upgrades If your projector comes with less than a three-year warranty as standard, it can normally be extended Each projector also has a number of features that build on these key functionality and performance indicators. Of all the features available on the market, we feel the most important for education is: Keystone Correction 'Keystoning' is the name given to the effect on the projected image when the projector sits below or above the centre of the screen. Keystone correction counteracts this effect by stretching the image at the bottom or top, resulting in a squarer, more professional image.
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