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Optoma HD91 Projector Review - Picture Quality 2

Posted on June 11, 2014 by Art Feierman
OPTOMA HD91 PROJECTOR – PICTURE QUALITY Page 2: Black Levels, Dark Shadow Detail As we consider in particular, the black level performance of the Optoma HD91 projector, a couple of thoughts. Everyone, I believe, agrees - a projector should reproduce deep "rich" blacks (ok, it's actually the absence of light) when called for, but there are many ways to achieve that.  Best of course is pure native contrast, but almost no projectors are so good at that, that further visible improvement isn't possible. Even JVC, whose $7000 and up projectors are the reigning champs at native black levels, have added dynamic irises to those projectors this year.  Everyone else starts at least a bit lower, but make use of dynamic irises, lamp dimming, or other methods to get those blacker blacks. Most would agree that having that blacker black on a bright scene is a good thing, but it's having those lowered blacks on very dark scenes, where they they make, by far, the most visible impact. Thus, a dynamic iris (or other similar techniques), can dramatically lower those black levels on dark scenes, while having virtually no impact at all on blacks on brighter scenes.  In other words, most effective when needed most.  There are trade-offs certainly, and those have to be weighed.  One potential problem for home theater projectors using dynamic solutions such as a dynamic iris or lamp dimming, is they have to do it so it's virtually unnoticeable.  Keep all that in mind.

HD91 Black Level Performance

As I've already discussed Optoma's Dynamic Black, which in this case is a lamp (or LED light source) dimming method, in the special features section, I'll try not to be too repetitive.

Overall black level performance of the HD91 is borderline what I call "ultra high contrast" when one of the three Dynamic Black modes are engaged   On the right scenes it can do a very respectable job, as seen in a couple of these images.

There are two issues though.  First, as previously mentioned, the dynamic aspects of Dynamic Black are far too visible.  Dynamic Black even causes very visible changes on medium bright scenes, where most dynamic irises intentionally are designed to minimize visibility.

On the classic dark scenes we look at, including the Casino Royale (Bond) night train scene, a dark scene from Hunger Games Catching Fire), and the starship in Fifth Element, blacks aren't bad, but not up to most of the competition found on over $2000 projectors.  Our favorite projectors around the price, BenQ's W7500 (also a DLP projector, and the one closest in black level performance), Epson's 5030UB/6030UB, Sony's VPL-HW55ES and JVC's X35, all are capable of from slightly to dramatically better.  If you turn off Dynamic Black completely, then the HD91 in those same scenes seems more typical of under $2000 projectors, which at its price point, is not exactly a "good thing!"

Why consider turning Dynamic Black off?  Because it is often visible, it can be a distraction.  Everyone is somewhat different -  for example; I rarely find audible projector noise to be a serious issue, but it is a big thing for some.  But most of us agree that black levels are a key performance issue.  I've recommended not using Dynamic Black in reviews of some other Optoma projectors in the past.  In the case of the HD91, I think that's a viable idea as well, at least for movies of certain types.  After much playing, Dynamic Black 1, which does the least, is the one I would normally use though, but even that setting can be noticeable on some scenes.  There are some illustrative photos in Dynamic Black section in this review.  The kids and other non-enthusiasts probably won't notice, but then, many of those are happy watching movies on 5 inch smartphone screens.  Go figure.

In the images here, all are typical dark scenes, but no two are particularly similar.  All of these exposures but the side by side and regular Bond night train scene are normally exposed so blacks are going to look pretty black, but on those last two, we've dramatically overexposed so you can get a feel for how black those blacks get.

In our side by sides, the HD91's on the left.  The other projector is the Epson Home Cinema 5030UB - the UB's being the best blacks per dollar of projector for a number of years now.  As you can see, the differences are rather dramatic.  Also of note, the Epson in the side by side is in it's calibrated mode, with lamp on Normal - which is their less bright eco mode in this case.  The Optoma is at full "lamp" power.  Even so, the Epson projector still produces the brighter image. You'll need to take that brightness difference in consideration when comparing the blacks.  Note that the HD91 projector had Dynamic Black set to 3, the one that most reduces the overall and black levels.

Even in Dynamic Black 3, and with the Epson being brighter overall, you can see in the letterbox areas and in the darkest parts of the woods, that the Epson's blacks are easily much darker.

On my computer colorimeter, for example, the dark areas are coming up as value 11-18 on the Epson vs. 23-33 on the HD91, a big difference.  And remember that near mid bright white areas on the HD91 are ok often as low as 170, while the same areas on the Epson because the image is brighter, are crushed at 255.

And you can appreciate that just by looking at this side by side train image.  On the Starship image the differences are even more noticeable and rather dramatic, the HD91 does reasonably well, but the letterbox and the background of space are significantly blacker, giving the image more pop.  The JVC and Sony competition would prove similar compared to the HD91.

Note that one can also use the LED Brightness section to dim the maximum brightness.  But on this projector there really aren't any lumens to spare, otherwise I would have checked to see if limiting the maximum brightness would have made the Dynamic Black action less noticeable.

Bottom Line on Black Levels.  While one could argue that they are respectable,  basic ultra high contrast, the problem is that I think for many of us, the Dynamic Black action is sometimes too noticeable, interrupting our immersion in the content on certain scenes.  Black level performance simply is not a strength.

Once again, therefore, black performance is an issue for an otherwise impressive Optoma projector.  Turn off Dynamic Black or use it's lowest setting:  1.  Unfortunately Dynamic Black's action is even visible on brighter scenes where it shouldn't be.  One of these days Optoma will develop a nice smooth "traditional" Dynamic Iris for their projectors, which will make several of their projectors far more competitive.

Recommendation:  Start with Dynamic Black 1.   If you find that its action on various scenes doesn't show up on your radar, great, try 2 or 3 and see how that goes.

HD91 Dark Shadow Detail

OK, the HD91's probably feeling a bit beat up by all my comments about its black level performance.

The good news is that dark shadow detail performance of the HD91 is excellent.  Again, look at our favorite image for dark shadow detail, which is the Bond night train.  In this case, note that we feel the Epson is at least very good at this, so to see that the Optoma HD91 is noticeably better is truly impressive.  Take a look at the shrubs on the far side of the train tracks on the right hand side.  There's definitely more dark detail visible with the Optoma.  You can even find some small amounts of very dark in the woods themselves, whereas with the Epson you can't discern those almost blacks from black.  True, projectors with less than great blacks tend to do well on dark shadow detail, as even those details must be lighter, since the blacks are, but in this case, the Optoma is doing a really first class job from any perspective.

Our small image player above serves up a few additional images suitable for picking out dark detail.  Bottom Line on the Optoma HD91 projector's handling of dark shadow detail:  Excellent!


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