This chapter outlines the theory which assumes the subject matter of buildings standing in their own grounds on a sunny day, with their main elevations varying in orientation within a southerly aspect. Such an assumption is necessary for outlining the underlying principles as a basis for this type of work. However, while many buildings do fall into this category, others inevitably do not in the day-to-day reality of practical assignments. When speed of results is the client's only priority the photographer is sometimes left with no choice but to try to achieve satisfactory results in less than ideal weather conditions. A relatively strong graduated filter is recommended when used in conjunction with an 81-series filter not just for contrast reduction but also to retain some of the blueness from graduated filter on film. Because the colours amber and blue neutralize each other in effect, a stronger blue is necessary to prevent the graduation effect.