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Optoma HD91 Projector - Special Features 1

Posted on June 11, 2014 by 

LED Light Engine

No matter what we find that the HD91 measures, know that an LED projector won’t lose any really significant brightness for many thousands of hours of use.  Since it claims about a 20,000 hour light engine it will likely be almost as bright as new, when it’s 4 or 5 years old.   So, know that the HD91 won’t get seriously dimmer over its useful life.  (If you use it even 40 hours a week, that’s a decade, before you get to the claimed 20,000 hours!

And therein lies the rub!  In far less than that time, low end projectors will be 4K projectors and higher end projectors will be sporting 8K.  In other words, if you were to buy an HD91 today, most likely you’ll naturally want to upgrade to 4K in a few years – 3? 4?  I would think in 3 years, four at the outside, 4K projectors will be down to current 1080p prices, and 1080p projectors will be your “entry level” projectors selling mostly under $1000.  The LED engine means you are paying up front, but saving you the cost of multiple $250-$500 lamps (if they are still that high in the future).   Problem is, many will make it through 3-4 years on a single lamp, and almost no one will need to replace lamps twice.

Here’s some relevant trivia: Japan apparently plans to be standardized on 8K resolution for broadcast by 2020… or at least that was the message I heard at the NAB show (National Association of Broadcasters) in April of this year.

On the plus side, though, a huge benefit of a solid state light engine like this one, compared to lamps,  is that they maintain color.  With lamps, you want the lamp to burn in for 100, maybe several hundred hours before calibrating, as the lamp’s color balance will shift slightly over time, so that for perfection in color, in theory one should recalibrate every 500 hours or so.  LED light sources are reported to be stable, color wise, so once calibrated, no real need to recalibrate, saving hassle, and or money.

The Lens

The manual zoom lens was a real surprise to me.  Rarely do we see a DLP projector with extensive zoom range.  Most have anywhere from 1.2:1 zooms to 1.6:1.  The Optoma HD91 though sports a 1.9:1 zoom.  That’s outstanding for a DLP projector.  The longest range zooms found on 3LCD and LCoS projectors tend to be 2.0:1 or 2.1:1, not noticeably different.  The key point here is that you have a lot of installation range.   The thing to remember though, is that to preserve the most brightness, you’ll probably want to mount the projector near the minimum distance for your screen.  Placing at the furthest possible from your screen will cost you almost half of the maximum brightness found when placing at the closest distance.

In part thanks to the lens, the image of the HD91 is very sharp, as one would expect from a single chip DLP with some good optics.

I like very much that the Optoma HD91 has a fair amount of lens shift, to enhance placement flexibility.   Without lens shift, you really need the projector precisely mounted at just the right height relative to the top of your screen surface, and accurately centered, left to right.

Projectors with lens shift allow a large range of placement vertically and usually, horizontally.  If you have a high ceiling for example, you’ll have to extend a projector  lacking in lens shift, down on a pole to about the top of the screen, whereas with another projector you might be able to place the projector up to 3 feet above the top of the surface, hanging down far less, or not at all.  We provide the vertical lens shift and throw distance information in our Hardware tour section of this review.

Pure Engine

Optoma places three sets of controls in what they call their Pure Engine.  Two sport the PURE moniker, and have been seen before:  Pure Motion is the HD91's  CFI – that is, their smooth motion, aka creative frame interpolation.  Pure Color, affect color dynamics, and is likely at least to a large degree Optoma’s variation of what the TI/DLP folks market as Brilliant Color, and offer to manufacturers that use DLP chips in their projectors.  Finally there’s Ultra Detail, which we can refer to as a dynamic detail enhancement system.  In this day and age, each of the HD91’s primary competitors also offer their own detail enhancement systems, which, btw, are smart, say, compared to traditional sharpness controls, although everyone seems to do those somewhat differently.

Let’s start with Pure Motion.

Pure Motion/CFI

CFI- Creative Frame Interpolation is now a pretty standard feature on most $2000+ projectors and found on some selling for far less. What’s it do for you? CFI looks ahead one or two frames, compares them to the “current” frame, analyzing what is different.   If a plane is moving from left to right across several frames, it notes that. CFI adds at least one frame between every two, so in the case of the plane, the inserted frame would have the plane half way between where it would be in frame 0 vs. Frame one.

The result is “smooth motion”   It does add lag as it looks forward, so turn it off for serious gaming.   The thing with smooth motion is how much to apply. Sports is a great use of CFI. It may make it easier to follow a hockey puck across the ice, or just make motion in general appear smoother. When applied to traditional movies though, which are at 24fps, and inherently a touch jerky, it really can change the look and feel of the content.  That’s generally not a good thing – as it destroys the “director’s intent”. Consider the Bourne movies where the director almost constantly has the cameras being a bit jerky.

CFI would minimize that, diminishing the “fast action” effect the director is probably trying to promote. Most serious enthusiasts will not use CFI, not even the smoother ones on their lower settings for movies, but, it’s up to you. If you like it, go for it. I find that younger generation folks, such as my just out of college daughter, aren’t the “purists” that would turn it off just because of the Director’s effect.

My daughter has been taught to immediately realize when it’s on, but is happy either way. Perhaps someday I’ll show her a particular movie, where she can appreciate that it was intended to look “this way.” And she’ll appreciate that.


So, how does the HD91 CFI perform. In addition to Off, there are three settings, Low, Medium and High. Low offers minor improvement when watching sports on HDTV. A basketball shot it a touch smoother but not fully so. Medium or High are better. The High setting is pretty tame compared to many others, for one thing I don’t notice the usually significant amount of noise right around those fast moving objects. Low or medium are probably just find for those that like CFI on regular TV, whether 30 Rock or Idol, or Blacklist.

Switching to movies running at 24fps off of blu-ray disk, where I’m not a fan at all of CFI,  I found Low to be fairly benign. It has very little of the “live digital video” aka “soap opera effect” that would be offensive to many. The Medium and High settings are very different from Low. Both immediately switch to that live digital video feel. Definitely “soap opera.” Both are way over the top for movie watching as far as I’m concerned, and they both much more similar to each other than to Low. Interestingly, even High did not show a whole lot of noise around the fast moving objects than many CFIs do show.

Bottom line on CFI. Sports – sure, go for it, medium or high settings. Normal TV, your call, but probably Low for most folks. Movies – Low may be acceptable to many of us who prefer none, but Medium and High are definitely way over the top for those concerned about the director’s intent.

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