TOKYO (Reuters) - Japan's Canon Inc (>> Canon Inc) on Tuesday reported a steeper-than-expected fall in first-quarter operating profit on weaker demand for office equipment in emerging markets and slower global sales of compact digital cameras.

The world's biggest maker of printers and cameras also cut its outlook for the full year ending December.

For January-March, operating profit dropped 39 percent to 40.1 billion yen (249 million pounds), the company said. That missed the 67.74 billion yen average of five analyst estimates, according to Thomson Reuters data.

Canon said it now expects full-year operating profit of 300 billion yen, lower than a previous forecast of 360 billion yen.

Quarterly operating profit from office equipment, its biggest segment, fell 38 percent from a year earlier while profit from imaging systems such as cameras fell 33 percent.

To reduce its reliance on cameras, Canon agreed to buy Toshiba Corp's (>> Toshiba Corp) medical equipment unit for 665.5 billion yen last month. The deal followed the purchase last May of 85 percent of Swedish video surveillance firm Axis AB (>> Axis AB).

The company, which earns about 80 percent of revenue overseas, said the yen's appreciation in the first quarter had a negative impact on earnings.

For the rest of the year, it said it expects the U.S. dollar to trade at an average of 110 yen compared with a previous assumption of 120 yen.

(Reporting by Makiko Yamazaki; Editing by Christopher Cushing)

Stocks treated in this article : Axis AB, Canon Inc, Toshiba Corp