Optoma GT720 Projector Review

Lens Shift

The GT720 gaming projector has a lot of fixed lens offset. That means that if you are setting it on a table, the bottom of the image will be well above the projector’s height. Per the manual, the numbers look like this:

For a 100″ diagonal screen, the center of the projector lens will be approximately 6.6 inches below the bottom of the screen.

Here’s a short section I’ve used in other reviews of projectors with about twice the offset (more common among DLP projectors, but it makes the point).

Consider, this common mounting situation:

8 foot ceiling, 120 inch diagonal screen:
Assume the projector is mounted about as close as possible to the ceiling, with a drop of about 10 inches from ceiling to center of lens.

Then, for the 120″ screen, the lens offset is just a fraction less than 20 inches. The screen height is about 59 inches. Bottom line: 96 inches (ceiling) -10, -20, -59 = 7 inches – the bottom of the screen would be just over 7 inches off the floor.

That much offset, though, is handy for placing a projector on a table below screen height, but is a challenge in those lower height ceilings if mounting.

Then consider a super popular sized screen – the classic 100″ diagonal (most folks seem to have from 100″ to 110″ best I can tell). Compared to above, the drop is 16.8 inches(call it 17), and the screen height only 50 inches. That now has the bottom of the screen at 19 inches off the floor. That’s reasonable if you have tiered seating, but really tough in the more typical non-theater environments where the GT720 will be watched. If you want a bunch of folks over, the ones in the back are going to have some real viewing problems with the picture starting only about a foot and a half from the floor!

From a table top standpoint, which is going to be a very popular way many people will use their GT720s, the extra offset is generally a very good thing. This allows you to have the projector completely below the bottom of the projected image. That means the table and projector won’t be blocking anyone’s view (unless they’re REALLY close to the floor). That 17 inches of offset is a real bonus. If you put the projector flush on the floor, for example, the bottom of the image (for that 100 inch size) would already be about 21 inches off the floor. (Note: remember you are measuring from the center of the lens height, not the top or bottom of the projector.)

Anamorphic Lens - Cinemascope

Of course not – this is a gaming projector, first and foremost. Buying a nice $2000 anamorphic lens, almost 3 times the cost of the projector (if it was even supported), really makes no sense, all considered.

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