By default Quake uses a FOV (field of view) of 90. You can set a higher FOV to distort your view to see more to the sides of the screen. Setting a higher FOV also means that the center of the screen will be "zoomed away".
If you are using a widescreen resolution to play Quake and keep the FOV of 90, you will actually play with a zoomed-in view instead of a realistic one. Widescreen means you should be able to see the same stuff like before but with additional space on the sides.
Lordhavoc was so nice to share the formula:
atan(tan(120*pi/360)*0.75*resolution_x/resolution_y)*360/pi
For your convenience, here is a table of some more or less common resolutions and the resulting FOV values.
fov 90 | fov 100 | fov 110 | fov 120 | |
---|---|---|---|---|
5:4 | 86.31 | 96.34 | 106.49 | 116.75 |
4:3 | 90 | 100 | 110 | 120 |
3:2 | 96.73 | 106.56 | 116.20 | 125.67 |
8:5 | 100.39 | 110.07 | 119.47 | 128.61 |
5:3 | 102.68 | 112.25 | 121.49 | 130.42 |
16:9 | 106.26 | 115.63 | 124.59 | 133.17 |
As you can see, if you use the equivalent of FOV 90 on eg 1680x1050 you get a FOV of 100 with no visual distortion. That's what widescreen gives you!
Some other resolutions:
fov 90 | fov 100 | fov 110 | fov 120 | |
---|---|---|---|---|
854x480 | 106.30 | 115.67 | 124.62 | 133.21 |
1024x600 | 104.00 | 113.51 | 122.64 | 131.44 |
1280x854 | 96.688 | 106.52 | 116.16 | 125.63 |
1366x768 | 106.29 | 115.66 | 124.61 | 133.19 |
2048x1080 | 109.78 | 118.92 | 127.57 | 135.81 |