Thank you Leif. Actually I own a 28mm 2.8 Ais (MF). Can it be reversed? How does it works? What devices/adapters will I need to reverse a lens?
Sorry for the questions but I often read things on lens reversed and have no idea how it works....
There are several approaches.
The simplest is to buy an adaptor - Nikon BR-2A - which allows you to mount the lens in reverse. You will need to focus at full aperture, then manually stop down before taking the picture as the aperture linkage will be lost. To focus you move the camera and lens, as the lens to sensor distance is fixed. If you reverse a wide angle zoom, you will get a range of magnifications.
An alternative is to use a long focal length lens, such as a 100mm or 200mm , and then mount a reversed lens such as a 50mm in front. The advantage is that you can maintain auto metering and aperture function, but you might get vignetting if you do not choose the lens carefully. This is sometimes called stacking lenses. To mount the lens you can glue together some step up/down rings which screw into the filter mounts of the lenses, but make sure the glue is effective as you do not want a lens falling off. The magnification is given by the ratio of the lens focal lengths
Many people such as John Shaw describe these techniques in various books. And a Google will provide some information too.
Note that focusing is very hard at 1:1 and greater, and vibrations are problematic. A focusing stage can solve the first problem.