) 
This is definitely one of the easier questions to answer when choosing a screen. The format may already be 
predetermined by your projection method and the type of information projected.
Aspect Ratio
Screen formats are quoted in terms of their width-to-height aspect ratio. For example, HDTV format is 1.78, meaning that the width of an HDTV 
format screen is always 1.78 times the height.
The variation of screen width for a given height is shown to scale in the figure at left.
It's important to match the screen format with the format of the projected content, since doing otherwise leads to wasted screen space and loss of apparent contrast.
For example, if you project an HDTV image onto a Video or Square format screen, there will be unused areas above and below the HDTV image, since you must to shrink the HDTV image to match the other format's width. The unused space is shown as the gray areas in the figure at right. In this example, an HDTV image is projected onto a square format screen.
In this case, the apparent contrast drops since the projected image is not surrounded by a matte black border, as it would be if projected onto an HDTV format screen. Believe it or not, the matte black border convinces our eyes that the projected image has increased contrast, so it is always better to fill the projected image out to the border.
If you must project multiple formats, the above scenario is inevitable. In that case, we suggest purchasing the format that you will use more often.
In some applications, so many formats will be used that it only makes sense to purchase a Square format screen to accommodate them all. One example is a traditional 35mm slide show, where both portrait and landscape photos will be shown. While Slide format (1.48) would fit the landscape photos perfectly, portrait shots will be shrunk to fit the screen height and loss of detail will occur. In this case, purchasing a square format screen will accommodate both landscape and portrait 35mm slides at full resolution.
The table below lists several common aspect ratios and their associated projection formats.
Aspect Ratio |
Decimal Equivalent |
Projection Format |
1:1 |
1.0 |
Overhead & opaque projection |
5:4 |
1.25 |
High-end data graphics |
4:3 |
1.33 |
NTSC/PAL video and most data graphics |
3:2 |
1.50 |
2x2 standard slides (35mm) |
16:10 |
1.60 |
WXGA (1280x800 pixels) |
15:9 |
1.67 |
WXGA (1280x768 pixels) |
16:9 |
1.78 |
HDTV |
1.85:1 |
1.85 |
Letterbox, widescreen, Panavision |
2.05:1 |
2.05 |
70mm film |
2.35:1 |
2.35 |
Cinemascope |
See Other Resource Pages
- Choosing the Best Screen Size
- Choosing the Best Screen Surface
- Da-Lite Screen Surfaces
- Draper Screen Surfaces
Clear as Mud?
Feel free to contact us with any questions.
