Japanese single lens reflex (SLR) digital camera makers are focusing on new models for professional and semi-professional users. Sony, Pentax and Olympus are displaying their latest prototypes of digital cameras at the Photo Imaging Expo 2007 being held in Tokyo.

Sony unveiled its plans for releasing two high-end versions of its popular Alpha 100 digital camera. Released last year, the Alpha 100 is the first camera to be developed jointly with Konica Minolta Holdings' former camera division, which Sony bought in 2005. Sony was displaying a mock-up and the new models don't have product names yet. For now, one is being called the "high amateur user" model and the other, the "flagship model" for professionals. Both models are scheduled to have the image stabilization feature already in the Alpha 100. The new models will include a new image sensor called the "BIONZ."

"We aren't releasing details on the price or features for these two new models," said Toshio Nagai, communication planning manager of the digital imaging business group at Sony.

Nagai would not say what resolution image sensors the high-end models would have. Some recent digital SLR cameras have sensors with resolutions as high as 30 megapixels.

The Alpha 100 has a 10 megapixel sensor, and the newer models will surely have more megapixels, be larger in size and heavier in weight, Nagai said. They are also showing eight new lenses for the Alpha series at the show.

"One of the two cameras will be released within the year, but we're not saying which," Nagai said. "We will be releasing five new lenses for the Alpha 100 within the year as well."

Meanwhile, Pentax is displaying a digital SLR prototype, provisionally known as the 645 Digital. It plans to use a CCD (charge-coupled device) sensor with a resolution of more than 30 megapixels.

"This is the third mock-up we have shown since the Fall of 2005. We've been changing our specs – we were originally going to offer 18 megapixels for this model – based on user feedback," said Pentax spokesperson Hiraku Kawauchi. He had no information about pricing or release date for the camera.

The lenses for the Pentax 645 will be compatible with the 645 Digital, he said. It will have two memory slots, one for Secure Digital (SD) memory cards and the other for CompactFlash.

Olympus had a mock-up digital camera called the "successor to the E-1" on display. "We are planning on unveiling and releasing this model by the end of the year," Olympus spokesman Atsushi Hatakeyama said. The company would give no further details other than that the new camera will have a dust reduction system. That was also a feature of the original E-1, which came out in late 2003 with a resolution of 5 megapixels.

A huge crowd gathered around the Canon Inc. booth, where visitors were able to actually hold the EOS-1D Mark III, which will go on sale by the end of May in Japan. The Mark III has a resolution of 10 megapixels, shoots at 10 frames per second, and will be priced at around ¥500,000 yen.

"People coming up to our booth are being blown away with the camera's live view mode," said Kiyokazu Danura, a Canon salesperson.

The Photo Imaging Expo 2007 runs through Sunday, 25 March at the Tokyo Big Sight exhibition centre.