Enlarger perspective control 

By tilting the easel slightly and projecting down on to the base board a limited amount of perspective control can be obtained. The perspective of an object can be distorted or corrected, but because the easel plane is not parallel to the lens and negative it can be impossible to have the whole image in focus. Focusing at the mid point on the paper and stopping the lens down will give enough sharpness to create an image that is convincing.

However, some enlargers also permit the neg carrier and lamp housing to be tilted independently of the lens which allows perspective control without the loss of sharpness. This is much the same as the movements on the 4x5 camera.