Benjamin Martin was a travelling lecturer who settled in Fleet Street in London in 1755 where he set up a shop for publications, instruments and demonstrations. Although popular, he fell bankrupt towards the end of his life. In his lectures on optics Martin would demonstrate the properties of lenses.
Benjamin Martin (1704?-1782): Philosophia Britannica: or A New and comprehensive System of the Newtonian Philosophy, Astronomy and Geography in a course of twelve lectures, 1759, vol. 3
This illustration shows how in a camera obscura (a dark room) a single lens is used to project an inverted image of a house and trees.
The lower image shows a solar telescope being used to observe the Sun in a darkened room, and a solar microscope used for magnifying very small and transparent objects, such as insects.