Complex sentence: The firm became very successful, providing both a studio portraiture service for the settlers and images of New Zealand landscapes and scenes of ethnogragraphic interest including Maori portraiture, which were in high demand by tourists and travellers to New Zealand and by other collectors around the world.
Split into simpler sentences: The firm became very successful providing not only a studio portraiture service for the settlers of the area but also providing images of New Zealand landscapes and scenes of ethnogragraphic interest including Maori portraiture. These images were in high demand by tourists and travellers to New Zealand and by other collectors around the world.