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Quick guide to slide projectors

An example slide projector

Slide projectors have traditionally been used to display photographs which had been transferred to see-through acetate 35mm slides which are then projected onto a projector screen.  There are not now many manufacturers of slide projectors as photography has gone digital which means that the demand for slide projectors has been replaced by a demand for digital projectors instead.  

The easiest way to explain the differences between slide projectors is to show a comparison chart of Reflecta models and explain the differences:




 Infrared Auto Magazine Zoom Colour Manufacturer Price


  remote focus systems lens   Warranty + VAT  

Let's start with watts.  The more watts, the brighter the image.  The 150 watt models display a bright image that in a room with dimmed lights would project well onto a large 6ft by 6ft screen.  A screen of this size would be fine in a school classroom, for example, where there is an audience of around 30 people.  Moving up to the 250 watt models, this is almost doubles the brightness.  This means that the screen size can double which is better for larger rooms and therefore bigger audiences.

To move to the next or previous slide, then you need to press a button on the remote control.  There are either a remote control on the end of a wire or a wireless infrared remote control.  Infrared is the same technology used on television remote controls, where you have point it directly at the television sensor to change channels.  Infrared slide projectors are slightly more expensive.

When you position a projector in front of a projection screen, then then lens will need focusing so that the slide is displayed clearly.  On most projectors you do this by turning a focusing wheel until the image comes into focus.  If you then move the projector, you will have to do this again.  Auto focus projectors do this bit for you.

Magazine systems are the type and shape of the trays that hold the slides.  For example, the slide projector at the top of this page uses straight tray system magazines such as Universal, CS and LKM.   Carousel slide projectors have a circular slide tray as in the picture below:
A Kodak carousell slide projector
So it is a case of using trays that match your slide projector.

In order to fill a projector screen, you move the slide projector back and place it until the image has filled the screen (within a range).    Zoom lenses allow you to change the size of the projected image by turning a wheel.   This means that you have a bit more control on where you place the projector in front of the screen as sometime you cannot put the projector the right distance away from the screen.

A couple of other things you may need to know if buying your first projector.  Slide projectors are quiet except for their cooling fans to keep the lamps from overheating the projector.  Slides can get jammed  but most new slide projectors have anti-jamming systems in place.

Slide viewers

You can use a slide viewer instead of a projector.  These are small, battery powered devices that allow you to slot in a slide and view.  They look almost like a small television. 

A slide viewer

Slide scanners

Slide scanners can be used to capture the image from a slight to your computer.   See  our article: convert slides to digital photos.