Originally Posted by Nicktx27
Okay, so then if I understand that if I do not clear the blades with the lens by say an inch or so then lens shift could allow that placement?
However, the top of the screen could be no higher than the 6-7" that the blades sit at?
Maybe, maybe not - but ultimately, that's immaterial: we're down to geometry, here :-)
Your fans are 7" off the ceiling. They're also close to the desired mounting-position for the projector. The projector naturally (with zero lens shift) projects at a very small angle downwards; meaning your resulting projected image is just a few inches below the lens.
If we were to draw an almost-straight line, at a very small angle, to the top of the screen - then mounting anything more than a touch above the height of the fan probably won't allow you to clear it at any amount of lens shift due to how close the fan is to the projector.
Use of the lens shift increases the projection angle, which, as geometry dictates, is how the projected image gets shifted downwards.
So the trade-off for mounting higher would be requiring more use of lens shift to get the image to clear the fan, which results in the projected image being lower.
Essentially, that means that mounting the projector itself with the lens just below the fan will probably nett you a higher-positioned image, compared to mounting higher and engaging full lens shift.
So no, the lens shift wouldn't help you much in this scenario.
So in summary:
Your best-case in terms of the maximum height of the projected image, then, is going to be employing zero lens shift, and placing the projector with it's lens just a touch below the fan.
Which means your top-of-screen can be at a maximum of a-few-inches-below the fan's 7" height off the ceiling.