。
She tried to focus on the flower.
Literal
She [topic-は] flower [on-に] focus match try-to did.
ピントを合わせる is the standard collocation for 'focus a lens, get something into focus.' ピント itself is one of Japanese's older loanwords, borrowed from Dutch 'brandpunt' (focal point) — a relic of the Dejima era when Dutch traders were Japan's primary link to the West. It's also used figuratively in expressions like 話のピントが合わない ('the discussion isn't focused'). Pairing the volitional 合わせよう with とする gives 'try to focus.' One small oddity: the natural particle for ピント here would be を (花にピントを合わせる) rather than と — likely a typo in the original.