ViewSonic PJD5112 , for example, are all perfectly acceptable choices. Choosing the best one for your needs can be harder.
All three of these models are portable, so you can move them from one classroom to another easily; all offer about the same brightness rating (2500 to 2600 lumens); and all throw reasonably good quality images. Beyond that, there are important differences that will matter more in some classrooms than others. To help make it easier to match your needs, we've compared them here point by point, and indicated which scored better in each case.
Advantage: ViewSonic PJD5112
The ViewSonic projector offers the brightest rating, at 2600 lumens compared to 2500 lumens for the other two. More important, we also measured it as the brightest -- and slightly brighter than its rating -- at 2747 lumens.
The Sanyo projector is also a little brighter than its rating, at 2562 lumens, while the Epson projector comes in below its rating, at 2284 lumens. All three are bright enough to throw a reasonably large image that can stand up to the lighting in a typical classroom.
All three projectors offer multiple preset modes, which you can use to lower the brightness for lower levels of ambient light. Here again, the ViewSonic PJD5112 is the clear winner with a range from 435 to 2747 lumens, depending on the setting.
The range for the Sanyo projector is 1204 to 2562 lumens; the range for the Epson projector is 1386 through 2284. All of these measurements were taken with the lamps in normal mode. With Eco mode, the lower number drops in each case, but even taking Eco mode into account, the ViewSonic projector offers the greatest range, and the Epson projector the least.
Advantage: Epson EX31
The projectors all offer image quality suitable for classroom use for both data and video, but each also suffers from at least one notable shortcoming.
The Sanyo and ViewSonic projectors are both single-chip DLP projectors, which raises the possibility of sequential color breakup (aka the rainbow effect). With data images, the ViewSonic PJD5112 shows less rainbow activity than most DLP projectors, so even those who are sensitive to it aren't likely to find it annoying. It's much easier to see rainbow artifacts with the Sanyo PDG-DSU30, so that students who see it easily may find it annoying for long sessions. With video images, people who are sensitive to rainbows will almost certainly see it with either projector.
As an LCD-based projector, the Epson EX31 isn't subject to sequential breakup. We saw noticeably lower contrast compared to the other two projectors, but the lack of deep dark blacks shouldn't be an issue a classroom or conference room, particularly with lights on. The projector's auto-iris feature also helps improve the perceived contrast in any case.
The Epson projector is clearly the winner for brightness uniformity, at 94%. The Sanyo PDG-DSU30 comes in at a respectable 72%, which is enough for the variance to be visible on a solid white screen, but hard to see with a screen broken up by text, graphics, or video images. The ViewSonic PJD5112 scored a surprisingly low 56%, and showed a noticeable hot spot that some might find distracting on data screens. Video images tend to be busy enough to hide even that much difference.
Advantage: ViewSonic PJD5112 and Epson EX31
All three projectors offer a reasonably full set of connectors for a portable projector, with at least one VGA port to connect to a computer or component video source, S-Video and Composite video ports, and a miniplug for audio input. The only additional connector on the Sanyo projector, however, is a pass-through monitor VGA port.
The Epson EX31 doesn't include monitor pass-through, but adds both a miniplug for audio output and a USB port. The USB port will let you control a computer mouse pointer or give page up and page down commands from the projector's remote, but it's notable for letting you send a data signal over the USB connection. (Although you can't send a data signal and control the mouse at the same time.)
The Viewsonic PJD5112 can't send data images over a USB connection, but it also adds a USB port for controlling a computer mouse pointer and giving page up and page down commands from the projector's remote. Other additional connectors include a miniplug audio output, a second VGA port for a second computer or component video source, a pass-through VGA port for a monitor, an RS-232 port to let you control the projector from a computer, and a 12 volt DC connector you can use, for example, to control a retractable screen automatically when you turn the projector on and off.
Suitability for moving a projector from room to room depends on a combination of factors, notably weight, ease of setup, and time to turn off. Virtually any projector can fit on an AV cart of course. These three models are all light enough to carry by hand as well, with weights that range from 5.1 to 5.7 pounds.
The Sanyo projector is unquestionably the easiest to set up. Front and back leg adjustments make it easy to point the projector up or down, and vertical and horizontal image shift settings plus a 1.1x zoom make it easy to adjust the position and size of the image.
Neither the Epson nor the ViewSonic projectors offer vertical or horizontal image shift, so you must position the image by moving the projector. Potentially complicating matters is that the ViewSonic model offers only front height adjustment, so you may have to prop the projector up on something to lower the image. The ViewSonic projector offers a 1.2x zoom lens for adjusting image size. Epson EX31's zoom is purely digital.
The Epson EX31 has the clear advantage of turning off quickly. You can unplug just 3 seconds after giving the power off command. The ViewSonic PJD5112 comes in second, needing about 60 seconds, with the Sanyo PDG-DSU30 a distant third at 120 seconds. Two minutes can be long time at the end of a class if you have to move the projector before the next class.
Gains in Eco mode
Advantage: ViewSonic PJD5112
Eco mode is available in each projector to lower brightness in exchange for a lower power draw and longer lamp life. The ViewSonic PJD5112 offers both the most to gain and the best balance overall on this score. The measured maximum brightness in Eco mode was 2392 lumens -- brighter than the Epson projector in Normal mode. Lamp life jumps from a rated 3,000 hours to 5,000 hours, making the small loss in brightness well worth the gain, especially considering the cost of the lamp -- $279 direct from ViewSonic or $199 street, with possible educational discounts that vary from one distributor to the next.
The Epson EX31's brightness dropped by about 20% in our tests in Eco mode, to 1793 lumens for the brightest setting, with the lamp life rising only from 4,000 to 5,000 hours.
The Sanyo DSU30's brightness dropped by about 14% in eco-mode, to about 2200 lumens, and lamp life is extended to an estimated 4000 hours.
Power Saving Features
Advantage: Sanyo PDG-DSU30 and Epson EX31
All three projectors offer standby modes of less than 1 watt, as confirmed by a Kill-a-Watt meter, which can measure only full watts, and gave a reading of 0 in all three cases. The Epson mode is rated at 0.3 watts. The other two are simply rated at less than 1 watt. Given the meter reading in all three cases, the actual difference between them is a few tenths of a watt at most, which isn't going to have enough effect on electricity use for the difference to matter.
All three projectors also offer timers to automatically turn off the projector after they lose a signal. In addition, the Sanyo projector offers a second timer that turns off the projector whether there's a signal or not, with settings up to 995 minutes, and the EX31 offers a timer to turn off after 30 minutes in mute mode. Note too that the EX31 saves a bit of power every time you turn it off by going to standby mode in just 2 to 3 seconds.
Advantage: Epson EX31
The Epson EX31 offers the strongest set of security features, with a security bar to wrap a cable around, power on password protection with 10,000 possible passwords, and the ability to create a customized startup screen. You can also add a Kensington lock as a $74.95 option.
The PJD5112 includes both a Kensington lock and security bar along with a power-on password and ability to create a customized startup screen. However, it allows only 16 possible passwords, so it's not a particularly strong security feature. The Sanyo PDG-DSU30's only security feature is a Kensington lock.
Advantage: ViewSonic PJD5112
There are also two issues that fall outside of the obvious categories, with one distinct plus for the ViewSonic PJD5112 and one minus for the Sanyo PDG-DSU30.
The PJD5112 is the only one of the three that's 3D ready. Although there isn't much you can do with 3D yet, having the feature means you won't need to buy a new projector when 3D software and video become available.
A potential disadvantage for the PDG-DSU30 is that it lacks any controls other than a power button on the projector itself. If you lose the remote, there's no way to adjust settings, making it hard to use the projector, until you get the $35 replacement. (Sanyo says that if you place an order before noon Pacific time, it will normally ship the same day.)
Possible Additional Costs
Advantage: Epson EX31
The Sanyo and ViewSonic projectors include only a power cord and VGA cable. The Epson EX31 adds a USB cable. In all cases, if you want to use any of the audio or video connections, you'll have to buy cables separately. One small advantage for the EX31 is that it comes with a soft cover to protect against dust and scratches. If you want a cover or case for the other two, you'll have to buy that separately as well.
The built-in audio in all three projectors is underpowered for a classroom. With any of these projectors, if you need audio, you'll need an external sound system.
There's little to no difference in maintenance for the three projectors. The ratings for lamp life for each vary depending on whether you use Eco or Normal mode, with ranges that overlap enough so none of the projectors has a definitive advantage over the others.
Beyond that, maintenance is essentially identical in all three cases, with little needed beyond using a small vacuum cleaner or brush to clean the vents periodically so dust won't clog the filter (in the Epson's case), or accumulate inside the projector (in the case of the two DLP models).
The EX31, as an LCD-based projector, is the only one of the three with a filter. The manual suggests replacing the filter only if you've managed to damage it or you've let it get so dirty that you can't remove the dust from it with a brush or vacuum cleaner. Even if you need to replace it, there isn't much work or cost involved. It's only $15 direct from Epson, and replacing it is a matter of snapping open a cover, sliding the old filter out, and sliding the new filter in -- a process that takes less time than cleaning the vents.
Advantage: ViewSonic PJD5112 and Sanyo PDG-DSU30
In most cases, the ViewSonic PJD5112 warranty will give you the most protection of the three, with 3 years for the projector and a full year for the lamp. (This is true for the U.S. at least. The length varies from country to country.) If you average 14-hours of use per day, however, the length drops to 1 year for the projector and 90 days for the lamp.
If you expect to use the projector that much, you're better off with the Sanyo's warranty, which is 3-years for the projector and 90 days or 500 hours (whichever comes first) for the lamp, without conditions on how much you use it.
The Epson EX31 comes in a distant third, with a one year warranty, although you can pay extra to extend it.
Advantage: ViewSonic PJD5112
Prices, of course, depend on where you buy the projector, but based on the information we got from each company, the PJD5112 is the least expensive. ViewSonic sells the PJD5112 directly for $679, but says its street price is $449, and it may be even be available for less. ViewSonic says it works with its distributors to arrange education discounts, but that they vary from one distributor to the next. Lamps are $249 direct from ViewSonic, or $199 street.
The only price Epson would give for the EX31 is $549.99 direct from Epson, with no educational discount available. Lamps are $199 direct from Epson and filters are $15.
The Sanyo PDG-DSU30 is $695 list, and $549 street. Sanyo was unable to confirm whether there was an educational discount available or supply a typical street price for the lamp. We found it online at prices ranging from $285 to $329.