Image quality is also affected by the type of screen used. Spheroid tubes are inexpensive, but can be difficult to view up close, since the center of the screen has a noticeable bulge. Flat-square screens are popular, particularly for larger monitors, because they reduce this curvature. Similarly, cylindrical tubes, such as Sony's Trinitron, use a slightly different design to reduce curvature, which can be preferable because it is not subject to as much glare from overhead lights. Another factor that affects image clarity is dot pitch.
Dot pitch indicates how closely the pixels are spaced apart on the screen.
A smaller dot pitch gives a screen a sharper appearance, while a larger figure will result in a fairly fuzzy image. Most monitors have a dot pitch of 0.28 millimeters. A dot pitch of 0.25 or 0.26 is slightly better, while anything over 0.30 is subpar. The vertical refresh rate is a final factor in determining a screen's usability. This is the rate at which the screen is redrawn each second.