We observed the field of GRB 100728B (Morris et al., GCN 11009) with the NOT equipped with StanCam, under poor seeing conditions. Observations were carried out in the R filter for 40 minutes, with mean time 18.36 hours after the GRB trigger. The seeing was 1.3". At the position of the optical afterglow (Perley et al., GCN 11007; Morris et al., GCN 11009) we do not detect any clear source, down to a limiting mag R > 22.2. By smoothing the image, a weak source can be marginally detected with magnitude R = 22.5 +/- 0.5 mag, calibrated against SDSS stars converted to Vega. We acknowledge the careful assistence of the NOT staff, in particular Anders Thygesen.