Rare prints made by the American photographer Paul Strand from his photographic essay in the Hebrides in the 1950s have been acquired by the Scottish National Portrait Gallery, each ‘a triumph of modest composition’.

One photograph is not the same as another. That’s the primary revelation from news that the Scottish National Portrait Gallery has bought nine images from the Hebridean work of renowned American photographer Paul Strand.

Strand’s classic book Tir a’Mhurain (Land of Bent Grass), written with essayist Basil Davidson, is the most acclaimed photographic book of twentieth century Scotland. Taken in 1954, the images of Benbecula, South Uist and Eriskay, are internationally known but have been exhibited only once north of the border.

The purchase marks the first time that this work has been represented in a permanent public collection in Scotland, but the real significance is less obvious.

Many of the images are familiar. The paradox of high art photography, however, is that mechanical reproduction does not make two photographs the same. For a technology designed to make copies, the photographs purchased by the Scottish National Portrait Gallery are as original as they come.

Most Strands on the open market are limited-edition authorized prints, posthumously made by a master printer from the original negative. Even then, you’ll need deep pockets. And the gradations in exposure, texture and tone that can be obtained from one negative are practically infinite.

The gelatin silver prints now on show in Edinburgh are, unusually, made by Strand himself – so they tell us a lot about how he wanted each image to look. Dark, yet richly textured.

The quality of the portraits, landscapes and close-ups is exquisite. Each subject is a triumph of modest composition; such detail and intimacy.

Behold the storyteller and singer Kate MacDonald, Bean Eairdsidh Raghnaill (or “Mrs Archie MacDonald” as she is captioned here); she’s in her Sunday best, her hairnet like a neat halo.

Facebook Twitter Pinterest Paul Strand (1890-1976) Mrs. Archie MacDonald, South Uist, Hebrides, 1954 Photograph (gelatine silver print): 11.4 x 14.6 cm Scottish National Portrait Gallery © Aperture Foundation Inc., Paul Strand Archive. Photograph: Scottish National Portrait Gallery

There are no epic landscapes like those of Strand’s friend Ansel Adams. This isn’t about grandeur – which is why they are surprisingly small: they are ‘contact prints’, each photograph exactly the size as the negative from which a tiny number were made.

Facebook Twitter Pinterest Paul Strand (1890-1976) Croft, Loch Carnan, South Uist, Hebrides, 1954. Photograph (gelatine silver print): 11.4 x 14.6 cm Scottish National Portrait Gallery © Aperture Foundation Inc., Paul Strand Archive. Photograph: Scottish National Portrait Gallery

These Hebridean images may not be so abstract as Strand’s earliest work, but they share the same modernist fixation. ‘Not just true to life’ as one critic noted, ‘but truer than life’.

But how to achieve this? It was all about the dark. Unlike many of his peers, Strand hated gloss paper. But nor could a fully matte paper quite convey the inky depth he needed. So he settled for a semi-matte and carefully layered varnishes or waxes until it conveyed the vocabulary of blackness. Not a quick process.

That level of fussiness never quite works in the mass production of books. Yet he obsessed so much about the reproductions in Tir a’Mhurain that it was sent behind the Iron Curtain to be printed (he was as doctrinaire about Marxism as about photography).

If you can ever find a copy of the original Tir a’Mhurain, it presents a more rounded project. The book form also allowed Strand to draw correspondences between images – like Peggy MacDonald, South Uist and Croft, Loch Carnan – a correlation that Anne Lydon, the International Photography Curator, has carefully preserved in the exhibition.

But these photographs are simply not like anything else. Just don’t think that by seeing them online you have truly apprehended the Hebridean darkness.