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Optoma HD72 Single-Panel 16:9 720p DLP Digital Projector

Part II

January, 2007

Darin Perrigo

 

Mounting the Projector

The HD72 has a 6.50 offset from the center of the lens to the closest edge of the image. For instance, if the projector is 10' back and everything is level, the edge of the image will be 13.7" below the center of the lens for ceiling mount, or 13.7" above the center of the lens for table mount.

For a 100" wide 16:9 (1280x720) or 5:3 (1280x768) image, the HD72 can be anywhere from about 158" (13' 2") to about 190" (15' 8") back. With the offset, as well as the throw range, it is important to determine whether this projector will fit well into a room. The offset may help in rooms with extra tall ceilings, but it would be a little difficult to deal with in rooms with short ceilings. Tilting both the screen and the projector can help counteract this fixed offset in setups where it does not work naturally, but this is really only for those willing to consider a little bit more difficult install than normal.

This projector has a feature to shift a 1280x720 image within the 1280x768 space vertically. Those choosing to use this projector with a 16:9 screen will end up with light spill above or below that area that is as bright as the black level of the projector. Masking or having this area behind the screen will pretty much make this invisible. A 15:9 (or 5:3) screen should match the image shape well, but would mean black bars with most content without stretching.

While a minor issue, I noticed some light coming out of the bottom of the projector (upper part when ceiling mounted) while in use. With the bottom facing a bright surface this could allow some extra reflection into the room.

The lens had more chromatic aberration than I expected. Zooming the lens causes the image to go out of focus, so both have to be adjusted together.

Setup

As can be seen in the photo below, as far as digital inputs, the HD72 has both an HDMI input and a DVI input. Having two digital inputs is uncommon even in projectors costing much more than this one. There are fairly inexpensive adapters that can be plugged into either input so that DVI cables can be connected to the HDMI input and HDMI cables can be connected to the DVI input if desired. However with one of each digital input type, the projector is ready to go for either DVI or HDMI cables without picking up an adapter.

I found that the DVI input behaved like a standard HDMI input, so it seemed to be DVI in only a physical connector way, other than also accepting DVI-A (or analog signals). What this means is, for source devices which have problems with their levels, colors, etc., when connected to DVI inputs, this does not apply to the DVI input for the HD72. For instance, as of the writing of this article, the Toshiba HD-A1 HD-DVD player crushes below-black levels or expands video levels to PC levels to standard DVI inputs, but does not have this problem when connected to the HD72's DVI input, because the HD-A1 doesn't crush below-black levels to standard HDMI inputs and this is basically what the HD-A1 detects over the cable.

I found that changes to settings in the menus, while using the DVI input for digital signals, stayed when switching to the HDMI input and vise versa. Without separate settings for the two inputs, it would be difficult to have separate calibrations for them, such as if one were to be used for standard video sources with standard video levels, and one were to be used for source devices sending out standard PC levels (like a PC).

The physical DVI input can also be used for analog signals from a PC by using a VGA to DVI-A cable or similar, but I did not try this.

Measurements

Here is what I measured for Color Temperature, RGB Levels, and Luminance (Gamma), respectively, with default settings in Cinema mode.

I then calibrated the projector, and here is what I measured for Color Temperature, RGB Levels, and Luminance (Gamma), respectively:

As shown by the RGB levels, there was some red drop-off near the highest IREs, which could be seen with a gray ramp as a little more reddish hue at 90 IRE than at 100 IRE. I did not see an easy way to fix it and left it like this.

At this point, there were about 30 hours on the lamp, which was set to low, and I used my settings I had decided on for Cinema mode. Using the 16:9 portion, since this is what I expect most people using this for home theater to use, I measured about 290 lumens and 1100:1 On/Off CR. Raising the Contrast and the value for Brilliant Color, while leaving the lamp on Low (without worrying about color balance), would have given about 700 lumens and 2750:1 On/Off CR. For ANSI CR I measured about 540:1, which is very good and in the normal range for DLP projectors (which tend to be higher than other projector technologies).

With the HD72, High Lamp to Low Lamp has a ratio of about 4/3. In other words, High Lamp is about 33% brighter than Low Lamp.

Viewing

I used the Toshiba HD-A1 with HDMI for playing HD DVD content, clips of various HD content I had burned onto DVDs, and commercial DVDs.

I did most of my viewing with the HD72 from about 1.5x the screen width, which I feel would be a reasonable viewing ratio for most people.

With a test pattern of a smooth grayscale, the HD72 did pretty well at not adding false contouring or banding. With some short clips I use for testing, it did well in avoiding false contouring with some, but not all.

I normally do not see many color separation artifacts (rainbows) with single chip DLPs having 5x color wheels. With the HD72's 4x color wheel that has a white segment, I saw more rainbows than I am used to at first, but they decreased with some viewing. Given that my experience is that the vast majority of people who don't know about the rainbow effect don't report seeing any problems similar to these when asked with DLPs with 3x color wheels, I wouldn't expect most people to see these artifacts with the HD72. However, those prone to seeing these with other home theater DLPs would be likely to see them with the HD72.

The shadow detail was about in the range I expect from single chip DLPs with no dark segment(s) on the color wheel, meaning that it was pretty good, but not as good as single chip DLPs with dark segments on the color wheel generally perform with some material.

The HD72 provides crispness to many of the images, which I find with DLPs in general. These can also look more detailed than some alternative projector types, although with low quality sources this can mean more visible artifacts also. With high quality HD DVD sources, the image quality looked outstanding from my viewing position.

Conclusions

The Optoma HD72 is priced within a very competitive section of the market.  Optoma has its own HD70, and Mitsubishi has the HD1000U below the HD72 pricing. There is also the Panasonic TX100U LCD at around the same price as the HD72.

For those who can deal with the throw and offset limitations of the HD72, it looks to be a competitive unit. With a higher budget, I would personally look for a 1280x720 DLP without a white segment on the color wheel (including Optoma's own HD7100, among others) if sticking with DLPs, but there are those who will value the white segment and brighter environments where that segment can be useful.


- Darin Perrigo -

Copyright 2007 Secrets of Home Theater & High Fidelity

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