Не будь раскадровки, режиссёр бы не выбрал крупный план.

Were it not for the storyboard, the director would not have chosen the close-up.

Breakdown of Не будь раскадровки, режиссёр бы не выбрал крупный план.

• не: not
• выбрать: to choose
• режиссёр: the director
• бы: would

Questions & Answers about Не будь раскадровки, режиссёр бы не выбрал крупный план.

What does не будь mean here? Is it the imperative of быть?

It looks like the imperative of быть, but in this sentence it is part of a fixed conditional expression.

Не будь раскадровки means something like:

• if there were no storyboard
• were it not for the storyboard
• had there been no storyboard

So this is not really telling someone don’t be. It is a set phrase used in hypothetical, often slightly bookish or formal, statements.

A fuller, less compact version would be:

Если бы не было раскадровки, режиссёр бы не выбрал крупный план.

Why is раскадровки in the genitive case?

Because the construction не будь + noun in the genitive requires the genitive.

So:

• не будь раскадровки
• не будь помощи
• не будь дождя

This matches the idea of absence / non-existence, which often triggers the genitive in Russian.

You can think of it as related in meaning to не было раскадровки, where раскадровки is also genitive.

Why is there no explicit verb like было in the first part?