The Optoma ML550 is one of the first of a new generation in the highly portable LED projector category. Meant for both business presentations and casual home entertainment use, it shares most of its features with other models in the same size and weight class, including a 1280x800 DLP chip and the ability to read files from microSD cards, USB memory keys, and its own internal memory so you can leave your laptop at home. However, it also pairs the small size of earlier generation 300-lumen models with a significant boost in brightness, at a rated 500 lumens and a measured brightness over 400 lumens. Widely available for a little less than $500, it's easily worth the price.
Like most projectors in its weight class, the ML550 uses a DLP chip designed to maximize brightness for small projectors. Unfortunately, it also adds apparent scaling artifacts. These are easiest to see as unwanted added patterns in large areas filled with repeating patterns of dots or fine lines. They can also give images a soft focus effect, making small text and fine details in line drawings hard to make out.
Similar artifacts show up with any DLP or LCD projector if you feed it an input signal that doesn't match it's native resolution. With the ML550, however, they show up even if you set your computer to 1280x800, so there's no way to avoid them. The good news is that you may not consider this a serious problem. Unless you use patterned fills in your graphics, you may never notice any artifacts. And if you don't need to show fine detail or small text in data images, you may not mind the soft focus effect either, although you'll likely notice that video and photos lose some crispness as well.
Data image quality. Although the apparent scaling artifacts and soft focus effect make the ML550 a poor choice for showing detailed line drawings or images with patterned fills, the projector did a credible job with the kind of images most people are more likely to use
Color balance was good, with various shades of gray acceptably neutral in most predefined image modes. Colors were suitably eye-catching in most modes as well, although they varied more from one mode to the next than with most projectors. Yellow, for example, was pastel, if not actually pale, in Bright mode; verging on lime green in PC mode; and definitively yellow in Cinema mode. You may want to pick a mode based on which colors you like best.
The ML550 also handled detail well enough for most purposes. White text on black was easily readable at 8 points, for example, and black text on white was easily readable at 9 points, with text breaking up at smaller sizes. Although that limits how much text you can put on screen at once and still be able to read it, it's easily good enough for images like a typical PowerPoint slide.
Video quality. Video is watchable with the ML550, but short of impressive as is typical for this class of projector. Predictably, the soft focus effect that grows from the DLP chip architecture makes the image look more like SD video than 720p HD. There are also issues with color. I settled on Cinema mode as the best choice for color quality overall, but even Cinema mode has some obvious problems. Most colors in most clips were a little washed out, but reds and blues in some clips stood out as oversaturated and shifted to the wrong hue, making them a little too vibrant.
On the plus side, the projector did an excellent job with shadow detail, and it showed only a hint of posterization in scenes that tend to cause that problem. It also handled skin tones well and showed minimal noise.
Other issues. Rainbow artifacts, with light areas breaking up into flashes of red, green, and blue, are less of a problem with the ML550 than with most DLP projectors, but still a potential issue. I saw few enough with data images and with most video that it's unlikely that anyone would be bothered by them. The one exception was a black and white movie clip, where the artifacts showed far more often. If you see these artifacts easily, you may well find them too annoying to watch black and white movies comfortably.
Another minor issue is that the projector's focus changes over about 10 or 15 minutes as it warms up. This can be a particular problem for business use, where you may start the presentation right after turning the projector on, and then have to adjust the focus two or three times, depending on how detailed your images are, before the focus settles into a steady state.
Good Connectivity. The ML550's back panel offers just a few connectors, but they're all you need.
Setting up. One minor setup issue is that if you want to show files directly from the projector's 1.5GB internal memory, you need a USB A to USB A cable to transfer the files. Optoma doesn't include one, however, so you need to buy one separately if you want to take advantage of the feature. You may also want to get the optional $20 tripod or $99 Wi-Fi dongle.
The vertical offset for the ML550 lines up the bottom of the image with the center of the lens. This is ideal if you're using a table-top screen on the same table as the projector. If you need to adjust the image position and don't have the tripod, however, you can either use the screw adjustment on the projector's front foot to raise the image, or simply rest the front or back of the projector on something to change the image height. You can then square off the image with the manual keystone control.
Setup is otherwise simple, with the focus tab offering just enough resistance for sure control. There's no zoom, however, so you have to move the projector to adjust image size. For an extended session in moderate ambient light, I settled on a 48" diagonal image, with the projector just over 6' from the screen.
As with any projector this light, the ML550 tends to pivot if there's any tension on the cables plugged into it. I usually solve that problem for testing by taping the cable down. However, putting something on the cable, like a paper weight, works just as well.
Highly portable. The ML550 measures 1.5" x 4.1" x 4.2" (HWD), and it weighs just 0.9 pounds by itself. Packed in the soft carrying case it comes with, along with the power block, power cord, remote, and combination VGA and audio out adaptor, the weight tops out at a still highly portable 2.3 pounds. Also adding to its portability is that it can read photo, video, audio, and Microsoft Office files directly from a USB memory key, microSD card, or internal memory, so you don't have to carry anything else with you. And the HDMI port lets you show images from any phone or tablet that supports MHL.
Low running costs. Optoma rates the LEDs in the ML550 at 20,000 hours, which means you should never have to buy replacements.
Brightness. I measured the ML550 at 414 lumens in its brightest predefined image mode and at 260 to 312 lumens in other modes. That makes the projector bright enough for extended viewing with a 48" diagonal image with moderate ambient light, or for a somewhat larger image for short sessions or dimmer lighting. I also measured a difference between white brightness and color brightness in Bright mode but not Cinema mode, which explains why Cinema mode offers the best color quality.
Good brightness uniformity. The projector did a good job maintaining uniform brightness, at 80% uniformity. You can see the difference with a solid color screen, but not with text, graphics, or video on screen to break up the image.
The only limitations worth mention that I ran into with the ML550 are typical for this category of projector.
Low audio volume. The 1-watt speaker is loud enough for a group of two or three people close to the projector, but low quality. If you need sound, you'll be better off with an external audio system or headset.
No zoom. As already mentioned, the ML550 lacks a zoom lens.
3D is highly limited. The 3D support is strictly for use with computers. As a practical matter, it's actually even more limited than that suggests, since 3D effectively cuts brightness by more than half.
Compared with other portable LED projectors, the Optoma ML550 offers the advantage of being smaller and lighter than most models with similar brightness, and brighter than most models with a similar size and weight. It can also free you from carrying or even needing to connect to bulky image sources like laptops. Instead, you can use a USB Key, microSD card, the projector's own internal memory, or a cell phone or tablet. Add in the good data image quality, watchable video, and sub-$500 price, and the ML550 is well worth a look.
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