Leica makes cameras that cost more than most people’s cars and are bought, in large part, for the red dot on the front. So there is a certain logic to a brand built on scarcity and prestige now being courted by a buyer with a taste for both. HSG, the Asian investment firm formerly known as Sequoia Capital China, has emerged as the front-runner to buy Blackstone’s stake in the company, according to Bloomberg.Blackstone holds 45% of Leica Camera AG, the holding it took as a strategic investor several years ago. The remaining 55% sits with ACM, the Austrian investment vehicle of the billionaire Andreas Kaufmann, who has been the brand’s steward through its modern revival. Both shareholders have been speaking to advisers about a sale that could value the Wetzlar-based maker at around €1 billion. HSG is said to be ahead of a small field that has included the buyout firm Altor Equity Partners.…