By using the relevant equipment, our ghost's attain that “authentic” look because we use a Fantascope to create a ghost in the way that we expect to see it: “imperfect, flawed and blurred.” For the same trustworthy reason that we expect Martians to be green! In other words:
conventional knowledge, creditworthy or not, plays an important role in the perception of an effect / illusion.

Throughout the history of audio-visual media - from shadow projection to the Nipkow disc and finally virtual reality of today - many people have been easily mislead by clever “charlatans” using various techniques. Schröpfer, Philidor, Robertson, Philipsthal, Ollivier, etc. are only some of those clever showmen who took advantage of the tumultuous times caused by the French Revolution, they saw and used this excellent breeding-ground to their benefit!

It's important to emphasis again that this and the following techniques where originally performed by back-projection through a translucent screen. In this way the origin of the projected ghost's remained hidden from the spectators. Unfortunately, because of a practical difficulties, such as lack of space, I was unable to experiment in this way. However, this has in no way hindered the results in the reconstruction of spectacular 18^th. & 19^th. Century Virtual reality projection techniques. Click image to see more fantascope prints

The different parts of the mechanical autofocus system and how it is synchronized with the front optical element of the Phantasmagoria lens, eventually leading to the wheels.

Because the system regulate the focus, the result in total darkness is a projected zoom-effect.

To improve the impact of the autofocus effect the phantasmagoria lens is equipped with a simple diaphragm, known as the Cat-Eye, mounted in front of the phantasmagoria lens. This simple changeable aperture, with only two blades, regulates the brightness of the projected image depending on the projection-distance.

Only during the effect of a “virtual screen” featuring a close-up of a subject (with the greatest distance between the screen and fantascope and the largest image), the cat’s-eye at its maximum opening. It needs to be closed gradually while the projection distance is shortened, to avoid an over-exposure of the virtual image as the projected image size is reduced.

If this procedure is not respected, the projected image would illuminate the darkened room and destroy the “approaching” effect, which is of the "utmost" importance! To make the ghost vanish, the cat’s-eye, which is string-operated, is simply closed by hand. As a result, the members of the audience are disorientated and on their guard. The cat eye is one of the most essential phantasmagoria accessories!

This is a primitive diaphragma, using only two blades to regulate the intensity of light when projecting distances are changing. this operation is done by hand, because it's not connected with the auto-focus system.
The manipulation is done by a string. A good synchronisation with the projection, open & close distance needs a lot of practice and expierience.