Hewlett-Packard DeskJet 720C

The most interesting aspect of HP's new personal inkjet, the DeskJet 720C, is that it shares its most important component - the print cartridge - with the PC Pro Recommended DeskJet 890C (reviewed issue 38, p168). It was this cartridge that helped the 890C produce some of the best colour output available from a desktop printer. Could it do the same in the considerably cheaper 720C?

The 720C is part of HP's series of personal inkjet printers, following in the footsteps of the 500 and 600 series in basic design. A paper tray at the front holds up to 100 sheets of paper. The paper is taken through the printer and reappears above the paper tray face up. To increase drying time, each new page is suspended above the output tray before dropping down onto the previously printed pages. It also follows the DeskJet 690C (reviewed issue 33, p127) in being able to handle continuous paper for banner printing and mirror-image transfers for making T-shirt designs.

Where the 720C differs from the 690C is in its approach to photographic-quality printing. The DeskJet 690C used a special cartridge for photographic printing that took the place of the black cartridge. This cartridge included two lighter shades of cyan and magenta in addition to black. By using these extra shades alongside the standard cyan, magenta and yellow, the 690C printed more colour variations and more subtle shading than with the standard colours alone. This system, known as PhotoREt, has now been replaced by PhotoREt II, which features in the 720C. First seen in HP's Professional Series DeskJet 890C, PhotoREt II uses a single cartridge that fires much smaller dots of ink. HP claims this technique provides up to 16 drops for each dot on the page, and so produces much more tonal variety for the same area of paper compared with other printers which can only manage eight drops per dot.

In addition to print-quality advantages, you don't need to keep swapping cartridges to match the print job; the standard cartridge is suitable for all pages. In fact, the 720C uses exactly the same ink cartridges as the 890C. In theory, then, the print quality from this printer should match the superb results of the Professional Series. Likewise, the rate at which the print head can fire ink at the page ought to be identical. The print speed should only differ between the two printers if HP has opted for a cheaper paper feed mechanism.

I started testing with plain paper. At three minutes and 35 seconds for a simple 20-page text document, the 720C is just short of 6ppm in Econofast (lowest-quality) mode. In the same mode a full-page photograph on plain paper took two minutes, representing exactly 0.5ppm. Increasing print quality to the highest-quality setting gave a print time of six minutes and 18 seconds for the 20-page text document, which is just over 3ppm.

With the best paper - Premium Photo paper - a full-page A4 photograph took just over eight minutes. All of these times are almost identical to those from the 890C, which is itself very fast for a personal colour printer. However, overall print quality didn't quite match that of the 890C. Text didn't appear as tightly focused on plain paper, although on coated paper it was much better. Also, one of the tables used in our business report printed with a mid-grey background in place of the light-yellow present in the original. The 890C managed to get these colours right.

For photographic output, however, the 720C is a very close match for the 890C. HP has also introduced two types of photographic papers. Our tests showed that the Kodak-developed Photo Deluxe paper gave by far the best skin tones, while HP's own Premium Photo paper gave skin tones a pronounced magenta cast.