CRT Size/LC: Although
manufacturers measurements will vary, these measurements are the agreed
upon measurements by most enthusiasts. Actual raster
corner to corner measurements will vary based on the installation. LC is
noted for tubes that are liquid-coupled (as opposed to air-coupled).
LC'ed tubes offer greater contrast and less halo'ing.
Analog chassis projectors use manual "pots" for convergence, image
sizing, shift, etc. With the newer digital convergence feature,
convergence is done from the control panel or infrared remote control.
This gives you the ability to stand at the screen and more accurately
set up the focus and alignment of the CRT's. Digital convergence units
also may have memories for different inputs and aspect ratios. These
can then be changed with the push of a button on the remote.
Peak Lumens: Lumens
relate to the amount of energy (light) that's coming from the CRT. It
describes the potential of the projector, but little of the actual
brightness you will get on screen. The brightness depends on many
factors. The most important being the screen size and material as well
as ambient light conditions.
Scan Rates and HDTV:
The ability of a projector to display HDTV depends on its scanning
capability. For example for a projector to line double standard NTSC
signals (480i at 15.75khz horizontal) from DVD, VCR or
cable/Satellite to 480p, requires 31.5 Khz of horizontal scan rate and
enough bandwidth to handle twice the picture information. HDTV at 1080i
requires a horizontal rate of 33.75 Khz and 50 Mhz bandwidth. 720p
requires a horizontal rate of 45 Khz with 50 Mhz bandwidth.
Max resolution: This is
the maximum resolution that the projector can accept (and sync to) as an
input signal. Important: While the projector
may be able accept the signal, it may not be able to fully resolve the
information on screen without overlapping of scan lines resulting in a
softening of the picture. That is, the manufacturer resolution specifications do not necessarily reflect real world resolving
Inputs: As listed above
V = standard composite video, usually a BNC connector on projectors
(takes a $2 Radio shack connector to convert back to RCA). S = S-video
in its usual form. R = RGB in either a DB type plug or 5 separate RGBHV
BNC type connectors. C = Component video. Any values in ( ) are
available with an optional input board.
A feature of a digital chassis where after doing a rough convergence you
can fine tune various areas of the image for a tighter alignment
Electromagnetic Focus: A feature on newer
projectors where you not only have the ability to focus corners and
center, but additional electronic controls for fine focus of the beam
spot throughout various areas of the image producing a sharper image.