iMac and Epson Projector

[chausman]

In my school, which was just built 3 years ago, we have some older iMacs and Epson projectors in each room. I think that the projectors are Epson PowerLite 83V+, but I can't tell for sure (being attached to the ceiling makes things difficult). In one of the rooms, when I changed the display settings form mirror to separate, so that I could get presenter notes on the screen, it worked fine. After I put the screen back, the iMacs screen would got pixilated and all of the icons on the desktop doubled in size and half completely went away. When I tried to change the resolution back to normal, but it would only work on one screen. If the iMac worked, the projector didn't. If the screen worked, the iMac didn't. It would only work if the projector was unplugged from the computer. The teacher uses the computer to project fairly often so just unplugging it isn't going to work. Does anyone have any ideals? (I'm just glad I wasn't in any kind of trouble)

 

[ruinexplorer]

The iMac is looking at the output of the projector. If the projector is only VGA (800x600) or XGA (1024x768), then the computer will match the highest output of the projector when mirrored. This will often change the way you can work on your computer if the resolutions do not match or just being a lower resolution than what you are used to. When the computer is set for dual display, it has the option of two different resolutions. If you are trying to force one display in mirrored output to a resolution that it cannot do, it will either pixelate or go blank as you described. In my opinion, I would keep the dual display as the default so that the teacher does not have to have the entire desktop showing while switching between presentations or anything else. The only caveat for that setup is to know that the presentations should be created in the native resolution of the projector so they don't look different than planned.