  Aims: We aim at investigating the time-behaviour of a sample of gamma-ray
blazars. We present the results from a 13 month-long optical photometry
monitoring campaign of the blazars PKS 0048-097, PKS 0754+100, HB89 0827+243,
PKS 0851+202, PKS 1253-055, PKS1510-089, PKS 1749+096, PKS 2230+114 and PKS
2251+158. Methods: We analyse the variability of each object, focusing on
different time-scales (long term, short term, and microvariability), in an
attempt to achieve a statistical comparison of the results. Results: After
applying a geometric model to explain the variability results, we found that it
is possible that a slight change in the direction of the jet generates the
variations detected in some objects during this campaign.
