How to choose the right projection screen for trouble-free short-throw projection

Short-throw projectors have become very popular.

At first they were used in combination with digital whiteboards.

But also for normal presentations they are the perfect solution in places where a large image needs to be projected from a short distance.

I work with projection screens every day and ever more often I meet dealers that we have to supply with a replacement screen: the projection screen delivered by their current supplier is simply no good.

That is because the flatness of the projection screen has to meet much higher requirements when used with a short-throw projector.

This situation arises when dealers and manufacturers of projection screens prefer to sell the more expensive tensioned screens and therefore provide the customer with insufficient information.

But there is a wide choice of perfectly flat projection screens available from a large number of suppliers.

This guide provides you with the basics of short-throw projection and why that affects the projection screen.

In addition we offer tips and advice to help you choose the right projection screen, independent from the choice of brand.

Finally we present you with a number of possible strategies that you can apply to make sure that you can safely install projection screens.

1. What is a short-throw projector?

In essence, a short-throw projector is a projector that can create larger pictures from shorter distances.

The advantage is that during a presentation the presenter is not standing in the light of the projector.

That way he or she does not cast an annoying shadow on the screen.

The presenter has the benefit that he cannot be blinded anymore by the light of a projector shining in his face.

What are the benefits?

A short-throw projector projects its light in a different way compared to a standard projector.

The angle is much larger allowing a bigger image to be projected from a shorter distance.

The images below show the differences.

First – the difference a short-throw set up would make in a class room or business presentation:

Advantage of short throw vs regular projection

Advantage of short throw (right) vs regluar projection

And here, you can see the diffence in the installation locations of a projector when using a short-throw projector.

short-throw and traditional projector installation position in a room

Differences in the installation position of a traditional and a short-throw projector

So much for the projector. What people usually forget is that the changed angle of the light coming from the
projector has serious consequences for the suitability of the projection surface: the projection screen.

3. What does this mean for the projection screen?

Projection screens must provide the best possible reflection of the projected image.

That is why the discussion is often about view angles, gain and reflection types.

Important issues for sure, but in the end the performance of a projection screen depends on how flat it is.

After all, waves in the fabric of the screen result in a distorted picture.

And for short-throw projection a perfectly flat screen is paramount, because:

The projection angle is much wider.

That has an effect on the visibility of any waves in the fabric.

The image below shows how that works.

impact of angle on crease visibility in projection screens

Impact of light angle on the visibility of creases in a projection screen

When there are waves in the fabric, then with a normal projector the incidence of light will produce only a slight
shadow.

However, with a short-throw projector you will see that the shadow is much larger when using the same projection screen.

So that means, that a projection screen that used to produce a good picture no longer meets the requirements.

Now what?

4. Better to go for tab-tensioned only then?

That is the answer you will get from many dealers when they receive complaints.

The answer to that question is: no, not necessarily.

For the screen manufacturers that would be ideal of course. A projector that needs a projection screen that is perfectly flat.

The best argument you can think of in order to sell the most expensive screen in your collection.

It reassures the customer and you make a nice profit.

But look at the image below: a tensioned screen can also have waves.

An example of a wrinkled, yet tab-tensioned projection screen

So be sure not to just use a tensioned screen.

A tensioned screen too must meet the requirements.

And, in terms of quality and price, there are quite some differences between the various tensioned screens.

What you do need to do however, is check out the quality of the screen.

For that I have to go back to the basics: projection screens must provide the best possible reflection of the projected image.

And that can only be achieved when the screen is perfectly flat.

5. The 2 options when manufacturing a projection screen

1. We use a rigid fabric that does not easily produce waves at the sides.

The screen flattens because of its own weight and rigid structure.

However for manual operated and low priced electrical screens usually a thinner fabric is used (up to
0.18 inch).

The thicker fabric (up to 0.59 inch) is used for the more expensive electrical screens.

Experience shows that the thin screens do not meet the requirements for shortthrow projectors.

You can get lucky finding the exception to the rule, but it is better to avoid these screens.

2. We use a slightly elastic fabric.

In the standard version a weighted lower bar produces the tension in the fabric.

The tensioned version has tensioning cords on both sides for additional tightening from the sides.

This is what such a screen looks like:

perfectly flat tensioned projection screen

Both these options are perfectly suited for short-throw projection.

Manufacturers worldwide use this type of fabric for frame screens, because it is the only way to get a 100% flat frame screen.

6. But why do not all manufacturers use this production method?

First, the fabric mentioned with the first option can be manufactured a lot more easily.

Especially when produced in large quantities.

Second, the production does not have to be customized.

What you have been able to see is that a screen that does not meet the requirements for short-throw
projection still can be used with a normal projector.

Finally, having a low priced product line is a good way to sell the more expensive projection screens.

7. Conclusion

A short-throw projector works in a different way than a conventional projector.

A projection screen will look wavy sooner.

This is not acceptable as the projection results in a distorted picture.

It means that the audience will not properly see or understand the content of the presentation.

Therefore it is better to choose a projection screen from a thin elastic fabric or a thick rigid fabric.

However, do ask your supplier for warranty to avoid that you get stuck with the cost of any replacements.