He was a Glasgow piano salesman, musician and businessman who in his spare time was the first man to document Scotland's beautiful landscapes in photographic form.

The pioneering work of John Muir Wood, who from the mid 1840s used the then-new technology of photography to document the Firth of Clyde and the North Ayrshire coast, is to be celebrated in a new exhibition at the Scottish National Portrait Gallery in Edinburgh.

His collection of more than 900 images, believed by experts to be the first serious series of landscape pictures of Scotland - and perhaps in the world - were kept in his family until 1987, when they were donated to the National Galleries of Scotland, Edinburgh.

Now, 20 years later, they are going to be displayed in an exhibition which will run from August 2 until October 26.

John Muir Wood was born in Edinburgh in 1805, and trained as a musician, but sometime after 1844 he took up the art for his own enjoyment, just five years after the early processes of photography had been first introduced to the world by the Frenchman Louis Daguerre and Englishman William Fox Talbot.

Muir Wood used the process pioneered by the Scottish fathers of photography, David Octavius Hill and Robert Adamson, a lengthy, delicate, and complicated process which produced images known as "calotypes".

Adamson began his photographic experiments in the late 1830s in St Andrews using the calotype process developed by Fox Talbot: the process produced a positive and a negative image for the first time.

Muir Wood took up Adamson's process, but instead of using it for portrait or documentary images, as Hill and Adamson had done, Muir Wood began to capture the landscapes of the West of Scotland providing modern viewers with haunting images of the rural world of more than 150 years ago. The calotype process was a lengthy one, with exposure times running from 10 seconds to 2 minutes, and movement was not easily depicted - people had to stand still or pose, and running water or quickly moving clouds appear as blurs.

However, the beauty of the images made by the process, which projected images on to high-quality watercolour paper, has led to experts comparing the work of calotype pioneers such as Hill and Adamson to the paintings of Rembrandt. Muir Wood's work largely came in a 10-year period after he moved to Glasgow and began to explore the West coast, after years he spent on the continent studying music in Paris and Vienna.

After settling in Glasgow, he used the new "excursion culture" of paddle steamers, as well as more traditional boats, to explore the Clyde and its surrounds. He photographed Largs, Arran, and the Isle of Bute as well as numerous other locations. Muir Wood, whose music business was successful and led him to promoting many classical concerts in Glasgow, died in 1892 but the exhibition will aim to bring the results of his pastime - he did not take his calotypes for profit, not intending to sell them - back into the public eye.

The selections of his work features images of towns and cities, including those captured on a continental tour in 1847; photographs of public monuments and private villas; and a dramatic series of Melrose Abbey taken probably in the early 1850s.

It will also show his images of North Ayrshire, the Kyles of Bute, and the mountains of Arran.

Duncan Forbes, the senior curator of photography at the National Portrait Gallery, said: "These are remarkable and pretty beautiful images.

"Hill and Adamson did not go in for a lot of landscape photography, perhaps because of the difficulties of the process itself and Muir Wood did something different. With calotypes it is difficult to get a sense of distance and atmosphere, and the equipment needed for it meant that Muir Wood involved a lot of heavy lugging of equipment up rivers and streams, followed by finding the right place and light and some complex chemical processes: so his images are a real feat.

"The images are a form of nature worship.

"He was a Christian and involved in the Church of Scotland and he would have seen nature as evidence of the divine.

"Muir Wood was the first systematic landscape photographer in this pioneering period and maybe even on a world level."

The exhibition will also provide some background to the importance of Muir Wood's imagery by displaying examples of the landscape practice of other early photographers, including Hill and Adamson, Horatio Ross, Dtk Drummond, John Forbes White, Roger Fenton and Fox Talbot.