Originally Posted by jeahrens
OK, now you're just splitting hairs
. The letterbox bars are there with or without the proposed lens. That they are present because part of the panel isn't displaying any information or because the panel is only optically filling the 2.35:1 area of the 16:9 screen isn't really relevant to the issue the poster is asking to be solved. They don't want the bars.
I think we're all in agreement that manually zooming is the best solution if image spill is not a concern. The Lumagen would work to zoom/crop and eliminate the image spill.
Seriously, not trying to split hairs. I was just trying to clarify. I wonder if we are talking about the same thing, actually.
Whenever I say letterbox bars, I am always referring to the extra 270 or so rows of pixels that are not in the active part of the image. When you zoom, the letterbox bars (the 270 rows of pixels) hit above and below the screen. By that definition, the bars are still there. And, with a DLP projector like the BenQ, are likely to be quite visible due to the elevated black levels of DLP (this is not a knock on BenQ or DLP technology in any way, as DLP has many advantages over other technologies - it's just that black level is not one of them). These could be quite evident on a drop down screen.
If he uses a vertical compression lens, those black bars literally go away. He would just need to zoom the projector in order to make the image fall off the screen - which he will need to do even if he goes with no lens. If he does NOT zoom the projector when the lens is in place, then you are correct - using the lens will not do what the OP is looking for. But either way he needs to zoom. He can zoom without the lens, or zoom with the lens. With the lens the image is brighter and there is no top / bottom overspill.
The reason why I said this is complicated is because he would also need to move the lens out of the light path whenever watching 16:9 if he wants maximum 16:9 quality. In other words, he would need a transport if he wants full quality 16:9. This is why I suggested calling Panamorph if he was going to do something along these lines so they could walk him through the ins and outs.
The OP says the Lumagen is out of his budget, but that lens is not. That would mean he is getting a pretty good deal on the lens (I'm assuming used). Is all this trouble worth it? Possibly, if the OP feels the improvement in brightness (which will be considerable) and lack of projected black bars is worth it. I just want to make sure he knows what he is getting into.
I agree with you that the Lumagen comes closest to doing what he wants - crop 2.35:1 so that it fills the screen. It would take care of image spill in every direction - top bottom and sides. The lens takes care of top and bottom (plus provides a considerably brighter image) but will actually make the side spill even brighter.