We report the results of CCD V , r and I time-series photometry of the globular cluster NGC 5053 .
New times of maximum light are given for the eight known RR Lyrae stars in the field of our images and their periods are revised .
Their V light curves were Fourier decomposed to estimate their physical parameters .
A discussion on the accuracy of the Fourier-based iron abundances , temperatures , masses and radii is given .
New periods are found for the 5 known SX Phe stars and a critical discussion of their secular period changes is offered .
The mean iron abundance for the RR Lyrae stars is found to be [ Fe/H ] \sim - 1.97 \pm 0.16 and lower values are not supported by the present analysis .
The absolute magnitude calibrations of the RR Lyrae stars yield an average true distance modulus of 16.12 \pm 0.04 or a distance of 16.7 \pm 0.3 kpc .
Comparison of the observational CMD with theoretical isochrones indicates an age of 12.5 \pm 2.0 Gyrs for the cluster .
A careful identification of all reported Blue Stragglers ( BS ) and their V,I magnitudes leads to the conclusion that BS12 , BS22 , BS23 and BS24 are not BS .
On the other hand , three new BS are reported .
Variability was found in seven BS , very likely of the SX Phe type in five of them , and in one red giant star .
The new SX Phe stars follow established PL relationships and indicate a distance in agreement with the distance from the RR Lyrae stars .