The second painting he shows Hemmings more closely resembles a drip painting by the abstract expressionist painter Jackson Pollock, which Bill claims has not yet come together for him and thus remains unfinished. Characteristically, Hemmings spontaneously offers to buy it. Later, after he has purchased a huge, unwieldy airplane propeller in an antique shop, the photographer himself indulges in a bit of aesthetic commentary when he borrows from Kant (without attribution!) to explain that he bought it because it is beautiful and that it is beautiful precisely because it is useless. Later, a direct link is made between Bill's paintings, Hemmings's photographs, and, by implication, the aesthetic project of the film, when the character played by Sarah Miles says pointedly that the photographs that Hemmings is enlarging have begun to resemble Bill's abstract paintings.
Joining the question of the nature of reality with the aesthetic question is the heavily foregrounded relation of the photographs to the "reality" that they have purportedly captured. In an important and often-discussed scene, Hemmings blows up his negatives to a larger and larger scale in order to seek a visual truth, that is, a correspondence between representation and reality. In so doing, he constructs a narrative, just as a director does in a film, by juxtaposing the individual shots and organizing them through the same system of looks that we know, from film theory, is what holds a movie together* In other words, Hemmings the photographer tries to construct a narrative logic through what is essentially a cinematic montage, and again Antonioni's camera (and eye) pans back and forth between the images, linking itself with Hemmings's eye and his camera. In fact, Antonioni keeps following (and underlining) the trajectory of an eyeline match with Hemmings's gaze, a standard visual suturing device in film, the device that makes space psychologically consistent for the viewer. By the time Hemmings's blow-ups reach the third degree, the camera is cutting back and forth between the photographer and the still photos, as though constructing a normal shot/reverse shot - the character looks, then we cut to what is being seen. Here the process is, in semiotic terms, paradigmatic or synchronic, as he goes "deeper" into the image. But it is also syntagmatic and diachronic, that is, through time, as when the montage is constructed by using several different still photos* The effect is to lay bare and thus demystify the filmmaking activity itself, because it is precisely by means of these two axes, the paradigmatic and the syntagmatic, that the cause and effect dynamic of meaning is accomplished in the cinematic editing process.
Most critics (and the director) have agreed that what this process demonstrates, paradoxically, is that the more the picture is blown up, to the point of abstraction, the less that is actually visible. This has never made complete sense to me, however, for Hemmings does in fact discover a gun and a body by means of the enlargements, and, when he goes back to the park, the presence of the body, at least, is verified by Antonioni's camera. It is as though the film were saying that "truth" can be arrived at even, or especially, through abstract representation. But what no critic to my knowledge has ever focused on is the fact that Hemmings takes a new photograph of a blown-up detail in order to blow it up even further. Yet this process cannot produce more bits of visual information that were not already there, and thus enlarging a photograph of an enlargement would be fruitless. This gesture of the photographer, fruitless or not, seems in any case to hearken back to something that Antonioni said years earlier, but that is especially appropriate for a discussion of Blow-up:
We know that under the revealed image there is another one which is more faithful to reality, and under this one there is yet another, and again another under this last one, down to the true image of that