The PB-4 was the first and only Bellows Unit from Nikon which offered “movements” - a sliding and tilting lens plane. (The contemporary PB-5 and later PB-6 were a similar units but without the lens plane movements). In fact the PB-4 had limited applications with most Nikkor lenses because they didn’t have the circle of coverage large enough for movements... but the Bellows-Nikkor 105 mm lens head did, albeit only a little. In the above illustration of the Bellows Unit the lens panel is tilted for maximum “visual impression” but is too much for acceptable results - there would still image coverage to the full extent of the 35 mm film frame, but in such a configuration the sharpness and resolution levels plunge to those produced intentionally by the new Lensbabies which are attracting a devoted following similar to that created by the Holga camera.

For serious photographic applications the PB-4 bellows and 105 mm lens are an excellent combo... but in this context “serious” covers usage limited to close-up photography with some movement to increase depth-of-field which is physically very limited at close-up working distances. The “tilting” feature increases depth-of-field whilst the “shift” feature enables parts of the subject to be included in the view without having to tilt the camera and thus cause distortion. However, the main use for the shift was to crop to a smaller part of a film transparency / negative original when using the matching PS-4 Slide Copier.