View > Camera Tools > Dolly Tool

Tracks the camera forward and backward. You can also press

(or

). Use

to drag a marquee around the area you want to dolly in on.

View > Camera Tools > Dolly Tool >

Scale: Scales the speed of the camera movement. The slider range is 0.01 to 10. The default value is 1.
Local: If on, drag in the camera’s view to move the camera toward or away from its center of interest. If off, drag in the camera’s view to move both the camera and its center of interest along the camera’s sight line. Local is on by default.
Center of Interest: If Center of Interest is on, -drag in the camera’s view to move the camera’s center of interest toward or away from the camera. If off, drag in the camera’s view to move the camera toward or away from its center of interest. -marquee a region and snap the center of interest to the center of those objects.Center of Interest is off by default.

If Center of Interest (and/or Local) and Bounding box are on, when you drag in the views, a red line with a small x at the end points to indicate the Center of Interest.
Towards center: Turning off this option dollies towards the current location of the Dolly Tool icon when you start dollying.

Snap box dolly to

A box dolly moves the center of interest to the marquee region when you use the ++drag (Windows and Linux) or ++drag (Mac OS X) method to dolly the camera.

Surface: If on, when you perform a box dolly (+drag) on an object, the center of interest moves onto the surface of the object. Calculating the surface point is slower if Smooth Shade mode is off (and especially if there are many visible objects in the scene).
Bounding box: If on, when you perform a box dolly (+drag) on an object, the center of interest moves to the center of the object’s bounding box. Bounding Box is on by default.