Mitsubishi obtained the rights to manufacture its own version of Sony's Trinitron tube years ago in a technology-sharing agreement between the two companies. Mitsubishi Diamondtron screens have since become more widely used by monitor builders than even the Sony variety, but Mitsubishi continued to develop the design and eventually came up with the Diamondtron NF - Natural Flat.

This tube isn't just vertically flat like the standard Trinitron/Diamondtron screen; it's also flat in the horizontal plane as well, neatly eliminating much of the remaining reflection from the screen surface, and allowing for exceptionally good image geometry in to the bargain.

The Diamond Plus 73 is based on a 17-inch version of the NF tube with the usual 0.25mm slot pitch and a fairly generous 15.9-inch viewable diagonal. The tube is relatively short-necked, so the cabinet only measures 420mm (16.5 inches) deep, which is good news if your desk butts up against a wall. It also helps keep the overall weight down to a manageable 18.8kg, but we did notice that the stand was still rather stiff, particularly when it came to adjusting the tilt.

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This is a fairly inexpensive monitor, especially considering that it's a big name product, and this explains features like the captive signal cable - cheaper, but potentially more trouble than a replaceable cable - and the absence of such extras as USB ports.

The on-screen setup menu is controlled from just three buttons on the bezel, but the arrangement is well thought out and provides reasonably fast access to all the options on offer, and the simple graphical style of the menu makes it easy to understand at a glance. All the essential geometry controls were present, including rotation and pin-balance as well as trapezoid, parallelogram and pincushion corrections, and we had no trouble in getting the edges of the image true. If you need to adjust the colour balance for any reason, say to match a particular printer, there are three preset colour temperatures and a custom mode with individual RGB intensity tuning.

With a 17-inch tube it's pushing the envelope to increase the resolution above 1024 x 768 (XGA) since everything on the screen starts to get too small for comfort and fine focus usually goes as well. The Diamond Plus was clearly designed with this truth in mind since it won't support the VESA-recommended flicker-free 85Hz vertical refresh rate beyond XGA - a clear sign that you aren't really supposed to go any further.

In XGA mode the picture is very clear, with good focus from the centre to the corners, and crisp reproduction of fine detail combined with the flatness of the image makes for an eye-catching display. The only thing we noticed which detracted from the overall effect was that the voltage regulation wasn't as good as it could have been, making the picture jump slightly in size if the image suddenly becomes darker or brighter, say when an application is maximised against a dark desktop.

That small flaw aside, the Diamond Plus 73 is a good deal, delivering the image quality of many more expensive monitors but at a commendably affordable price.

The Diamond Plus 73 is a basic, no-frills display which offers good image quality at a competitive price. Its flat screen helps it to stand out from its competitors, by reducing unwanted reflections and improving geometry.