I usually use a tilt-shift lens for both interior and exterior architectural photography.This lens gives the same effects that used to be obtained by swing and tilt photography using a large format camera with bellows.

In the film photography era such lenses were readily available from many suppliers including Mamiya and Olympus, but nowadays the only suppliers are Canon, Nikon, Schneider in Germany and Samyang in Korea.

Talking about lenses angle of view, in the 35mm film era a 28mm focal length lens was a common wide angle lens, but now 24mm lenses are widely used. The smaller the focal length the wider the field of view.

There also exist extreme wide angle lenses with 12mm focal length now available: their field of view is so large that when used with a tripod care must be taken not to include the tripod’s legs in the picture.

I personally prefer a 28mm lens, because wider angle lenses cause perspective distortion effects. Photographing a rectangular object close up and from an angle causes unnatural looking distortion of the corners. I have 17mm ultra wide angle and 24mm tilt-shift lenses which I use when appropriate.

One more point: it is now easy to digitally process photographs so that they appear to have been taken using swing and tilt photography. I think many photographers feel that it is no longer necessary to own a tilt-shift lens and that a normal ultra wide angle lens will suffice. This is a mistake.

In architectural photography it is normal to align the camera with the horizontal and vertical axes of the building. However particularly when photographing exteriors using such alignment it may be impossible to include the entire subject in the picture.

Using a tilt-shift lens with the lens shifted upward it is possible to include the top of the building in the picture. With a normal ultra wide angle lens the camera must be tilted upwards, and this alters the perspective of the picture with the result that the top of the building appears too narrow.

This may be digitally corrected, but this correction changes the composition of the picture, which can be extremely undesirable. If digital perspective correction is to be used it can be very difficult when shooting to accurately judge the final composition of the end result.

Because of this many architectural photographers still use tilt shift lenses.

In addition to the shift function, tilt shift lenses allow tilting which enables accurate control of depth of field without changing focus. Because of this, tilt shift lenses with longer focal lengths, such as 90mm, are often used to good effect for product photography.

To summarize, tilt-shift lenses allow a photographer to easily envisage the final result when a photograph is being taken and thus ensure optimal composition for a perfect result.