Setup and Configuration
Review: Optoma HD91
LED 1080p Home Theater Projector
March 26, 2014
With a 1.9:1 zoom lens and H/V lens shift, it's not difficult to get the HD91 set up in a typical home theater environment. However, the relatively low light output of the projector means that you'll be better off placing the projector as close to the screen as possible to avoid further light restriction from the zoom lens.
The HD91's 1.9:1 zoom lens will allow you to display a 120" diagonal image at throw distances from 13' 1" to 25' 2". However, at maximum telephoto, the lens loses 46% of the projector's total light output, bringing our test sample's 517 lumens in Cinema mode down to only 278 lumens. That's usually not enough light for a 100" diagonal screen, only giving 12 foot Lamberts on a 1.3 gain surface. If you need to use the telephoto end of the zoom to achieve the placement you want, consider going down to an 80" diagonal screen with a mild positive gain in order to boost image brightness. This goes double for 3D projection, where brightness is further curtailed.
As far as lens shift goes, the manual H/V shift will allow you to place the image either completely above or completely below the lens centerline, for a total range of two image heights. Horizontal shift gives you about 25% of the image width in wiggle room. The lens shift range is elliptical, not square, so you cannot use the projector's full horizontal and vertical shift ranges at the same time. There is no decrease in light output when using the extreme edges of the lens shift.
The HD91 is quiet during operation, though it does have a characteristic LED hum that we have noticed on several LED-based projectors. It is not loud enough to be annoying, at least in our estimation, but it can be noticeable during quieter scenes if you have the projector positioned close to the audience.
In summation, the best place to mount the HD91 is in a ceiling mount or low table placement at the minimum throw distance for the desired image size. If you can manage a rear shelf mount while still avoiding much use of the zoom lens, this is another viable option. Use a screen surface with a mild positive gain, and eliminate as much ambient light as you can.