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Slide projectors

How to choose a slide projector

Comparing slide projectors from spec sheets is a little more difficult than you might expect, because the items you most want to compare–image quality, brightness, and reliability–aren’t given in the specs.

On the other hand, the technology has come far enough that these three items really aren’t a big issue. If you stick with a projector built for professional use, the main question becomes one of the features you need versus the budget you have available.


The most important specifications

  • The focal length of the lens you choose for your new projector determines the screen size you can fill at a given distance. The following table shows the approximate throw distance needed (from film plane to screen) for various screens and focal lengths.
Screen width
Lens 60" 70" 84" 96"
35 mm. 5.2 6.0 7.3 8.3
50 mm. 7.4 8.6 10.4 11.9
90 mm. 13.3 15.6 18.7 21.3
100 mm. 14.8 17.3 20.7 23.7
150 mm. 22.2 25.9 31.1 35.6
200 mm. 29.6 34.6 41.5 47.4
250 mm. 37.0 43.2 51.9 59.3

Because most people use their projectors in different rooms at different times, zoom lenses are the most popular United sells.

  • Compatibility can be an issue if you plan to use your projector with a dissolve unit or multi-image programmer, particularly if you’re considering a projector mainly intended for home use. By and large, the projectors in this catalog will work with the majority of programmers available, but it makes sense to check before you buy.

  • Slide changing time refers to the minimum time it takes to cycle each slide in and out of the projection gate. This, again, is a consideration if you’re planning to use your projector with a multi-image program.


    Useful features

  • Remote focus can be extremely useful, as most people find it easier to focus their projector accurately while standing close to the screen than from the back of the presentation room.

  • Auto focus can also simplify the setup process, but is most useful as a means to ensure that each slide in a given tray stays in as sharp a focus as the first.

  • An extra lamp module will allow you to get up and running quickly should a projection lamp fail during a presentation. (Simply pull out the whole module and slide in the new.) The newer Ektapro projectors can include a dual-lamp module, which automatically switches to a new lamp when the old one fails.

  • A preview screen allows you to look at a tray of slides in your presentation room without having to show them to your audience.

  • A reading light is not actually for reading, but is included to allow you to identify a tray or look at an individual slide in a darkened room.

  • Random access allows you to project any slide in your tray at any time.

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