Considering its importance as a means of communication, architectural photography is a relatively underdeveloped field in this country. Every week, for example, this page carries images of buildings which, if of a sufficiently high standard, are far more eloquent than the accompanying text. Yet the number of photographers who specialise in architecture remains small and inevitably this has an effect on the quality of work being produced.

At the moment, the RIAI is exhibiting a selection of architectural pictures taken by a master of the form, Norman McGrath, who has been refining his skills for more than four decades. The son of the late Raymond McGrath, principal architect at the Office of Public Works from 1948 to 1968, he originally trained as a structural engineer. However, after moving to the US in 1956, McGrath's photography gradually turned from a private to a professional interest and by the early 1960s it had become his career. Although largely self-taught, he did take some courses with a number of people, such as the influential art director Alexey Brodovitch.

Since then, based in New York, he has worked as a photographer of architecture and interiors. His book Photographing Buildings Inside and Out first appeared in 1988 and was republished in a revised and expanded form five years later; having sold more than 46,000 copies, this manual is surely now due for a new edition.

His other books also include Manhattan Skyscrapers, which appeared two years ago, and next spring, a book on New York's lost and lamented Pennsylvania Station - demolished in 1963-64 - will include some 75 photographs taken by McGrath.

"That was a terrible thing when they tore the old station down. I lived a couple of blocks away and was working in an office directly opposite the building so I had plenty of opportunities to take pictures. I was one of the few people to use both colour and black and white film."

His images of Penn Station in the forthcoming book will be in colour, but he expresses a personal preference for black and white. In part, this is simply due to his age; as McGrath says, "almost all photographers of my generation were brought up on black and white images and that only really changed in the 1970s when it became much more economical to reproduce in colour."

But, just as importantly, "black and white reduces the subject to its most basic elements of form and texture, light and dark. Sometimes colour gets in the way, it becomes another element."

McGrath picked an excellent moment to embark on his chosen profession, because in the early 1960s, there were relatively few photographers specialising in architecture. One of that handful was Julius Shulman whose work has recently undergone a huge revival of popularity, thanks in part to renewed interest in mid-20th century Californian design, which was always his speciality.

"Shulman was on the spot on the west coast at a time when a lot of Bauhaus and early modernists like Richard Neutra had emigrated there," McGrath comments. "He got to know them and was given a lot of encouragement."

But he believes that much of Shulman's work reveals the dangers of including people in architectural photographs because it has the effect of dating the work rapidly. The outcome is that the pictures become more important as historical records than as opportunities to examine the specifics of design.

Asked what qualities are needed by a good architectural photographer, McGrath observes that anyone entering the profession "must have infinite patience and a great awareness - especially in interiors - of what space is all about."

He argues that far greater skill is required when photographing inside a building compared with its exterior, not least because "you have to be a lighting specialist. I've always tried in my pictures to capture what it's like to be in a space but that's difficult. You have to use a wide-angle lens to get the whole thing, but this causes distortion so there must be a compromise; you must give a sense of what's going on without being disturbed by that distortion."

McGrath's training, he believes, was particularly helpful in his photographic work because "my engineering background gave me the ideal start to understanding buildings." Nevertheless, it took time to become established in what was a relatively little-understood field.

As well as getting to know a large number of architects and designers with whom he subsequently worked, "in order to make my name, I decided immediately that I had to have my pictures published, so I made myself known to all the relevant magazines and publications in America. It turned out to be the correct decision and gradually my work became known and was published widely."

In fact, there can scarcely have been an architectural journal since the 1960s which has not used McGrath's work. He comments, for example, on a series of images he took of Charles Moore's Piazza D'Italia in New Orleans.

One of the first instances of post-modern urban design in which an unexpected mΘlange of materials and design elements were mixed together, this structure - and McGrath's images of it - received widespread attention and now that the plaza needs to be refurbished, his pictures are being used by the relevant authorities as a reliable guide to its original appearance.

While still working as an architectural photographer, McGrath now finds a great deal of his time taken up holding workshops around the US for others who wish to enter the same profession. "I enjoy it," he says. "I find that I learn from my students, it keeps me alert and on my toes, and I have access to equipment I mightn't otherwise use." On a visit to Dublin last week, he found time to hold just such a workshop here. Perhaps his inspiration will lead to an increase in the number of photographers offering this service in Ireland.

Now and Then, an exhibition of architectural photographs by Norman McGrath can be seen at the RIAI, 8 Merrion Square, Dublin until Friday, November 16th