John Benjamin Dancer was born in London in 1812. In 1835, John took over his father, Josiah’s, instrument-making business. He continued in business in Liverpool until 1841, when he entered into partnership with A. Abraham, a scientific instrument maker of Lord Street, Liverpool. He moved to Manchester to establish a branch of the business as Abraham & Dancer at 13 Cross Street. The partnership ceased in 1845. Dancer continued in business under his own name until 1878 when part of the business was transferred to his daughters Elizabeth Eleanor and Anna Maria.

Dancer became well known for the quality of his microscopes and particularly for selling good-quality instruments at a relatively low price. He received several honours which reflected the high quality of his microscopes, including a prize medal at the International Exhibition in London. He was appointed Optician in Manchester to the Prince of Wales. Dancer also supplied apparatus, including a travelling microscope and thermometers, to James Prescott Joule in about 1844 for his work on the mechanical equivalent of heat. Joule described Dancer's thermometers as "the first which were made in England with any pretensions to accuracy". Dancer is perhaps best known for his photographic work, in particular on microphotography and the stereoscopic camera. He took the earliest known photograph of Manchester - showing the cutler's shop at 1 Market Street - in 1842.

In February 1852, Dancer produced his first microphotographs. These were tiny photographs on microscope slides, which were viewed through a microscope or viewer. They soon became very popular. Dancer produced photographs of many subjects including eminent scientists, religious texts and sights such as Niagara Falls. Dancer's friend, Sir David Brewster, exhibited some of the microphotographs in Florence and Rome and showed them to the Pope. At the London Exhibition of 1862, Dancer received an honourable mention for his invention. In Dancer's lifetime, this technology only had a novelty value, but microfilming, as it is now known, became commercially important in the twentieth century as a means of copying documents.

Dancer died in November 1887, while living with relatives in Birmingham. He was buried in Brooklands Cemetery in Sale, near Manchester. In 1960, the National Microfilm Association of the USA awarded the Dancer Pioneer Medal with the citation: "To John Benjamin Dancer, a man of strong character and immense energy; alert and practical, a skilled craftsman and manipulator; sympathetic, ever ready to help the youthful searcher, inventor of microphotography, the National Microfilm Association is proud to present this posthumous Medal of Meritorious Service to the microfilm industry."