# [clug] Monitors that swivel

Alex Satrapa alexsatrapa at mac.com
Fri Jun 5 00:54:17 GMT 2009

```On 05/06/2009, at 09:48 , Lana Brindley wrote:

> 'Scuse my ignorance ... what exactly does the 40° viewing angle
> mean? Why does this have that end result?

Here goes my "Dummies Guide to Viewing Angles". I have no idea what
the target audience already knows, so pardon me if some of it is
oversimplified or attempts to teach grandma how to suck eggs:

Look at your monitor from dead in front, you're now at 0° from the
"normal" (the normal being a line perpendicular to a plane). If you
imagine a bottle sitting on a table, the vertical axis of that bottle
is parallel to the "normal". Now sit the bottom of a bottle against
the monitor, again the long axis of the bottle is parallel to the
"normal".

you're increasing your viewing angle from 0° to some other deviation
from the normal, in the horizontal direction. A monitor with a 130°
viewing angle will give you consistent quality image when you move to
the left or right in such a way that your deviation from the normal is
up to 65° (at this angle, you're basically looking at the monitor from
the side, as if you were the second person to the left of the person
driving the computer).

So too, you have vertical viewing angle, which means that if you move
in the vertical direction. A viewing angle of 40° will usually mean
that the monitor is designed to allow you to go "down" by 10° or "up"
by 30° - the monitors are designed to have people looking at them from
normal ergonomic positions with eyes 1/3 down from the top of the
monitor and this viewing angle allows you to see even tones across the
vast vertical expanse of a 24" landscape monitor for example.

A little detour, if I may, into the world of LCD technology. The
simplest way to understand LCDs is that the "liquid crystal" part of
the technology is (I'm oversimplifying here) tiny flat crystals that
can be twisted around by the electric field passing through the pixel.
So for "white" you'd have the red, green and blue shutters "wide
open", for "black" you'd have the red, green and blue shutters
"closed". For greys, you'd have the shutters twisted partially open.
Imagine the shutters as being miniature venetian blinds. If they're
partially closed, moving from side to side will not alter your view of
the world outside the window. If you move up or down, the blades of
the venetian blind will end up being rotated relative to your
position, and you'll see more or less of the world outside the window.
Now replace the world outside the window with the backlight of the LCD
monitor, you have a decent analogy to the LCD technology.

When you twist that monitor on its side to give a "portrait" display,
suddenly you have a 40° horizontal viewing angle, which means that
even with two eyes in the same head from 50cm away, you can
potentially see different shades of colour from one side of the
monitor to the other when displaying a "black" image. That is, you've
turned the venetian blinds into vertical blinds.

In such an instance, you either have to sit further away and off to
the side, or close one eye (ie: reduce the difference in angle between
each eye and the points on the screen, or reduce your point of view to
one viewing angle). Neither situation is particularly comfortable.

Portrait orientation can still be useful if you're editing documents
that consist largely of black text on a white background - the
differences between "navy blue" representing black at one side of the
monitor and "Cayenne" representing black at the other side of the
monitor won't cause too many problems. White is pretty uniform, since
white is achieved by having all the shutters open. You'll get some
grey at the extremes, which looks like vignetting.

Hope this helps. And again, apologies for the oversimplification.

Alex

-------------- next part --------------
A non-text attachment was scrubbed...
Name: PGP.sig
Type: application/pgp-signature
Size: 220 bytes
Desc: This is a digitally signed message part
Url : http://lists.samba.org/archive/linux/attachments/20090605/913dfaa8/PGP.bin
```