I dont know the technical reason, but this is why think it is
by telling the projector you are using 1365x1024 it knows that you are telling it that it is a 4x3 projector (I know that sounds weird)
Technically all the projector is doing is that it is shooting a 16x9 image inside a screen. It has no idea if the screen is 16x9 or 4x3, but it will place the image in the same location. So if you had a 4x3 screen, the top of the 16x9 image would be lets say 8 feet of the ground, with top third of the 4x3 screen being blank. If you use a 16x9 screen, again, the top of the 16x9 image will still be 8 feet of the ground. It makes no difference what screen you use, the image will appear in the same location. Of course unless you have a scaler that allows you to move the to the top or bottomor the 4x3 chip, but lets not get into that
So it makes no difference what screen you are using. However, the projector resolution (1365x1024 4x3) needs to match the output resolution of the scaler (1.33 or 4x3) for it to work properly.
Everything I am saying only applies to 16x9 material and wont work with 4x3 material
Probably and I have never really tested it, if you tell the scaler 1365x768, then I would guess you would tell the scaler to use 1.78 screen. I did try it once with the digital Leeza, but I got double images which could probably have been corrected if I adjusted some feature. Supposedly the 1365x768 was made for plasmas, but it could have worked I have been told
At first glance you are right, it seems like you should set it to 1.78
One finaly point, when you add a anamorphic lens to the projector, then you tell the scaler that the screen is now 1.78 because in reality your projector has been transformed from a 4x3 projector to a 16x9 projector
By the way, I am not clever enough to have come up with this way of doing this. Mark Rejhon the king of dscaler and one of the creators of the Rock and the Digital Leeza told me how to handle this.
Why it works, who cares, all I know it does.
