Optoma HD91 LED Home Theater Projector - Performance

Posted on June 11, 2014 by Art Feierman

OPTOMA HD91 PROJECTOR - PERFORMANCE PAGE 1: Measured Brightness all modes, Calibrated Brightness, Effect of Zoom Lens, Effect of "LED Brightness settings", Color Temp over IRE range Pre Calibration

HD91 Brightness in Different Modes

Optoma HD91 Brightness/Color Temp - Image Modes, Pre-Calibration
Picture Mode	Lumens	Color Temp
Cinema	526	5831
Reference	384	5661
Photo	476	6395
Bright	753	6626
User	359	5145
Film	368	5126

Let's take a quick look at the "out of the box" brightness numbers. At mid point on the zoom only Bright mode, which is pretty ugly, is noticeably above 500 lumens.

Mike reported: None of the modes are good by default (too much red), but Photo has slightly better RGB balance than Cinema.

None the less, for other reasons he didn't mention, he determined that Cinema was his top choice to base the calibration on.

Mike didn't comment, but based on how close the numbers look, it would seem that out of the box, User is based on the Film default.

HD91 - Post Calibration

HD91 Post Calibration Brightness - Mid-point on zoom
Cinema (Calibrated)	Bright (after Quick-cal)
552 Lumens	668 Lumens

552 lumens is pretty low by today's standards for mid-point on the zoom lens (especially for a 3D capable projector), but there is a sliver lining hidden in the numbers. More on that in a second. Meantime, Trying to improve Bright mode with a Quick-Cal - which is our term for seeing how much we can improve the color balance of the brightest mode without sacrificing more than about 10% of brightness. (If we have to adjust it so much that it's not noticeably brighter than "best" mode, then why bother?)

Zoom Lens Effect on Brightness

Effect of Zoom on Lumen Output (Bright mode)
Zoom Out (wide angle)	1000 Lumens
Mid-point	753 Lumens
Zoom In (telephoto)	509 Lumens

OK, about that "bright" piece of news. As discussed earlier, the HD91 has a lot of zoom range. Not only that but there's a huge amount of drop in brightness going from closest (wide angle) to furthest (telephoto), even more than in any of the projectors that have slightly more zoom range like the JVCs and Epsons.

Since we primarily measure at mid-point, that means that there's a bigger drop there too, in lumens compared to wide angle. Therefore the silver lining is that if you can mount near full wide angle (about 11.5 feet from a 100" diagonal screen), you get a big boost in brightness.

As a result,, going to full wide angle from mid-zoom buys you a 32% increase in brightness based on our measurements That means if you mount at the absolute minimum distance, based on Mike's measurements you would have just over 725 calibrated lumens. Our brightest usable mode - Mike's "quick-cal" of Bright mode measures out to 882 lumens.

Editor's note: Mike recently switched to a new meter. This one is measuring about 10% higher than his old one. The old one, we felt was a bit low, this one a little on the optimistic side. He started using the new meter with the JVC RS4910 review.

Something to consider: One of the reasons I chose to focus on mid-point zoom for measurements when we started, is it was a way to partially compensate (in terms of claimed brightness) for the expected drop off in brightness over the lifetime of the lamp. With LED there's still a drop off, but it isn't as great and takes far, far, longer. If you are worried about enough brightness, you could figure that an LED projector with 3000 hours on it probably hasn't dropped much brightness (10%? - I have no good numbers). But a 4000 hour lamp, might be down 35%.

Therefore, while a calibrated projector like the Epson 6030UB might start out brighter calibrated, there will be times before lamp replacement where the Optoma HD91 might actually be brighter. (In an example like this, the Epson would be brighter on average, but nice to know that the HD91 won't be losing many lumens until the projector is pretty darn old.

"Eco Mode"

Effect of LED Brightness Setting (Reference Mode)
100%	384 Lumens
75%	292 Lumens
50%	201 Lumens

The Optoma HD91 doesn't really have an Eco mode, but you can dial down the maximum LED brightness which should reduce the amount of wattage the projector draws.

At full power, this projector draws about 250 watts, which is lower than most home theater projectors, which tend to run from 250 watts to around 400 watts. I know Optoma touts the low wattage, but if you consider the relative brightness of the projectors, almost all of the competition, using the same or only modestly more power, produce up to more than double the brightness, and most produce at least 50% more lumens in their brightest modes.

In other words, it might slightly reduce your electric bill compared to the competition running at full power, but most competitors running in their eco modes compared to this projector at 100% LED Brightness, are still brighter, and draw less juice. DLP's overall tend to be the hungriest, so any real savings is likely to occur only when comparing against another DLP, such as the BenQ W7500. That BenQ is way brighter, but draws over 50% more wattage.

Pre Calibration Color Balance

Pre Calibration Color Temp - Across IRE Range
IRE	Cinema	Photo
100	5831	6395
80	4922	5562
50	4773	5377
30	5065	5456

Neither of these modes to start is anywhere near averaging 6500K. Both also move further toward red as the image gets darker. Fortunately, the Color management system and the gray scale controls work well. Or, as Mike put it:

Grayscale calibrated reasonably well, with only a bump at 100 IRE (to 7.5) detracting from a very good average Delta E of only 1.0 from 20 to 90 IRE. The RGB balance was also good and other than the bump in red at 100 IRE, was consistent across the whole IRE range. The RGB controls worked like they’re supposed to, with adjustments to Gain and Bias only having small effects on each other.

Gamma has a number of available adjustments that allow you to get a good average. However, I had to adjust the Film gamma from its default (which should be around 2.2) to 2.5 to get a 2.2 average. This results in an average of 2.18, but is not consistent across the range.

Per one of Mike's charts (on the advanced calibration page for our subscribers), the gamma quickly lowers in number as one moves up from 80 IRE. As a result there's a high gamma in the dark scenes, adding to the richness, but also making them seem a little darker, while very bright scenes are more "TV" like than movie.

Bottom line on the Gamma, the final number looks really good, but the gamma isn't consistent as it should be, across the range.