Context :

Aims : We have performed a photometric V,R,I CCD time-series analysis with a baseline of \sim 8 years of the outer-halo globular cluster NGC 7492 with the aim of searching for new variables and using these ( and the previously known variables ) to determine the physical parameters of interest for the cluster ( e.g .
metallicity , absolute magnitude of the horizontal branch , distance , etc .
) .

Methods : We use difference image analysis ( DIA ) to extract precise light curves in the relatively crowded star field , especially towards the densely populated central region .
Several approaches are used for variability detection that recover the known variables and lead to new discoveries .
We determine the physical parameters of the only RR0 star using light curve Fourier decomposition analysis .

Results : We find one new long period variable and two SX Phe stars in the blue straggler region .
We also present one candidate SX Phe star which requires follow-up observations .
Assuming that the SX Phe stars are cluster members and using the period-luminosity relation for these stars , we estimate their distances as \sim 25.2 \pm 1.8 and 26.8 \pm 1.8 kpc , and identify their possible modes of oscillation .
We refine the periods of the two RR Lyrae stars in our field of view .
We find that the RR1 star V2 is undergoing a period change and possibly exhibits the Blazhko effect .
Fourier decomposition of the light curve of the RR0 star V1 allows us to estimate the metallicity [ Fe/H ] _ { ZW } \sim -1.68 \pm 0.10 or [ Fe/H ] _ { UVES } \sim -1.64 \pm 0.13 , log-luminosity \log ( L / L _ { \odot } ) \sim 1.76 \pm 0.02 , absolute magnitude M _ { V } \sim 0.38 \pm 0.04 mag , and true distance modulus of \mu _ { 0 } \sim 16.93 \pm 0.04 mag , which is equivalent to a distance of \sim 24.3 \pm 0.5 kpc .
All of these values are consistent with previous estimates in the literature .

Conclusions :