We have carried out photometric monitoring of the bright flat spectrum radio quasar 3C 454.3, which has exhibited remarkably high activity and pronounced variability at all wavelengths since 2001, to search for optical variability on a wide range of timescales. CCD magnitudes in B, V, R and I pass-bands were determined from 63 optical observations made during 2011 – 2014, with an average length of ∼ 4 h each, at seven optical telescopes: four in Bulgaria, one in Greece, and two in India. We measured multiband optical flux and color variations on diverse timescales. Discrete correlation functions were computed among B, V, R, and I observations, to search for any time delays. We found weak correlations in some cases with no significant time lags. The structure function method
was used to estimate any characteristic time-scales of variability. We also investigated the spectral energy distribution of 3C 454.3 using B, V, R, I, J and K pass-band data. We found that the source almost always follows a bluer-when-brighter trend. We discuss possible physical causes of the observed spectral variability.