D-ILA Projectors » Reference Series

ID #1275

While setting up Lens Memory I was able to size the 2.35:1 image to fit the screen but now I can’t zoom the 16:9 image small enough to fit the screen. Why is that?

You are probably too far from the screen to have enough zoom range to accommodate both 16:9 and 2.35:1 formats.  The normal zoom lens range of the projector for any single image/screen size is 1.4:1 – 2.8:1 (throw ratio).  However, when you use both 16:9 and 2.35:1 formats on one screen you’ll need to size the image at two different zoom lens positions, and that will limit how far away you can place the projector.  The effective zoom range that can accommodate both 16:9 and 2.35:1 formats on one screen is 1.4:1 – 2.1:1 throw ratio.  It’s a matter of physics.

Sometimes it’s easier to explain a situation by using a real-life illustration:

  1. Suppose your screen is a 100” wide, 2.35:1 screen.
  2. The projector has been installed 280” from the screen, which happens to be the theoretical maximum throw distance (100” x 2.8). Note that this will put the lens zoom fully at the end of its range (maximum tele).
  3. The lens shift (position) and zoom settings are then adjusted to fill the height and width of the 2.35 screen for a widescreen video source, and the settings are then saved.
  4. The video is then changed to a 16:9 formatted source. Of course, this image will be over-scanning the screen top and bottom and will need to be sized smaller using the zoom lens. However, it is impossible to make the image smaller because the lens is already at the maximum zoom position. Obviously, you will need to move the projector closer to the screen in order to fit the 16:9 image height to the 2.35:1 screen. That is your limiting factor. Therefore, the maximum throw distance when using lens memory for both 16:9 and 2.35:1 formats is 1.4:1 – 2.1:1.

Last update: 2012-02-01 15:24
Author: Ken Bylsma
Revision: 1.0

Print this record Print this record
Send to a friend Send to a friend
Show this as PDF file Show this as PDF file
Export as XML-File Export as XML-File

Please rate this entry:

Average rating: 2.33 out of 5 (15 Votes )

not useful 1 2 3 4 5 most valuable