Whereas pictorial space plays an important role in art historic discussions, there is little research on the quantitative structure of pictorial spaces. Recently, a number of methods have been developed, one of which relies on size constancy: two spheres are rendered in the image while the observers adjusts the relative sizes such that they appear to have similar sizes in pictorial space. This method is based on pair-wise comparisons, resulting in n(n-1)/2 trials for n samples. Furthermore, it renders a probe in the image that does not conform to the style of the painting: it mixes computer graphics with a painting. The method proposed here uses probes that are already in the scene, not violating the paintings' style. An object is copied from the original painting and shown in a different location. The observer can adjust the scaling such that the two objects (one originally in the painting, and the other copy-pasted) appear to have equal sizes in pictorial space. Since the original object serves as a reference, the number of trials increases with n instead of n2 which is the case of the original method. We measured the pictorial spaces of two paintings using our method, one Canaletto and one Breughel. We found that observers typically agreed well with respect to each other, coefficients of determination as high as 0.9 were found when the probe was a human, while other probes scored somewhat (but significantly) lower. These initial findings appear very promising for the study of pictorial space.