In photographs, as in art, the scale and size of various elements can serve various purposes. For landscape images, including an element of known size will help viewers make a relation or size reference to the objects in the photo. Also, the relative sizes of objects add depth and perspective to a two-dimensional image. Thirdly, the relative areas occupied by one shape to another can indicate major-minor relationships and show dominance of a subject. 

In the “Frozen Lake of the Rising Sun”, the inclusion of the couple walking their dog gives a scale reference, showing the immense height of the ice mountain built on the lake’s surface. Similarly in “Fantasy Flight”, the difference in size between the large wing tip and the smaller airplane near the bottom of the image depicts the relative distance between the two.

Frozen Lake of the Rising SunEarly morning walk on the frozen lake at Crystal Beach. The transparency of the dog-walkers mimics the translucent ice, as if they're being melted by the rising sun.       Fantasy FlightTwo planes flying by the moon.

For architectural photos, the diminishing sizes of objects provide a sense of depth and perspective. Two examples are seen in “Galleria Wave” and “Rhythm and Blues” with the red balls and blue columns decreasing in size into the distance.

Galleria Wave *Wave sculpture of red balls in Galleria.   Rhythm and BluesThe rhythmic pattern of blue-lit columns leads to the light at the end of the tunnel.

The large size of the statues in “Farewell My Sailor” are of dominance (major elements), while the smaller boats in the background are supporting (minor) elements to the story. On the other hand, in the abstract “Sun and Moon”, both circles are of similar size, both being equally important as the sun and moon in the image.

Farewell My SailorA wife bidding farewell to her husband before he sails off into the sunset.          Sun and MoonLights through a screen forming an abstract sun and moon in the sky.

When composing your photos, including elements of varying sizes can help with the story-telling aspect, either by providing scale references or showing major-minor relationships between subjects/objects, giving your images the desired impact.