The economic waters may be rough right now, but the managers of an Atlanta private equity fund say it's time to dive in. Buckhead Investment Partners recently completed a $30 million capital raise, which it plans to invest over the next few years in private companies in the early stages of growth. The deep recession has made investing in any business more risky, experts say.It's also thinned the ranks of private equity firms willing and able to invest and driven down the valuation of companies, said Mark Buffington, a managing partner at Buckhead Investment Partners.