Commonalities and differences
It belongs to the old dreams of humankind to see away things close (telescope) and small things large (microscope) also it was a desire to look into the human body through natural cavities without harm. (endoscopy)
All three products have a similar structure made of a metal cladding tube and an optical system consisting of eypiece lens and lens array.
The microscope was the first invention of this three different products, invented about 1590. The Inventor cannot be determined, it was probably built by the Dutchman Hans Jannsen 1595. Antoni van Leeuwenhoek (1632 - 1732) also a Dutchman built about 500 microscopes. The lenses had 1.2 mm Diameter and a radius of 0.7 mm, the cut was carried out in excellent quality.It was possible to achieve with this microscopes a magnification up to 270 times. A significant improvement was reached in 1816 by the German Josef von Fraunhofer. He developed a much more improved type of glass and designed achromatic lenses. He included them in his microscope, which remained unrivaled in quality for long times. 1823 improved the the Paris physicist Sellique the microscope objective by merging up to four achromatic cemented components (plan-concave and bi-convex). Beside the advancement of optical components also the mechanical parts were new designed, completed and became better and better.
The telescope followed the microscope as invention a few years later. It was invented in 1608 by the Dutchman Hans Lippershey. As a result, the properties of telescope and microscope have been continously improved by extending the knowledge of light and optics and improvment of lens grinding and mechanical parts. After Lippershey particularly Galileo Galilei and Johannes Keppler are to mention as significant contributors to development and dissemination of the telescope. Big influence also had the scientists Isaac Newton (1643 - 1723) and Christian Huygens (1629 - 1695) by defining the properties of light.
All These inventions represented not only progress for the development of the telescope and microscope but also formed the basis for the development of endoscopy, initiated by Philipp Bozzini 100 years later.
The endoscope followed the two inventions about 100 years later. The problem was probably due to the lighting. The only possible remedy was lighting by a candle at this time. In 1800 the candle was industrially-manufactured and was affordable, before that it was a luxury good.
Lighting - the big Problem of endoscopy. The candle was the first artificial light source to illuninate body cavities. While the illumination of objects in microscopy and telescopy carried by natural light from outside, the illumination of body cavities was much more complicated because it was carried out indirectly via mirrors and lens systems. The candle as a light source was not suitable because of poor light intensity. Therefore only lenses could be used with a small opening angle, so both framing and resolution was inferior.