We demonstrate a temporal imaging system based on parametric mixing that allows simple triggering from an external clock by using a time-lens-based pump laser. We integrate our temporal imaging system into a time-to-frequency measurement scheme and demonstrate the ability to perform characterization of temporal waveforms with 1.4-ps resolution and a 530-ps record length. We also integrate our system into a temporal-magnification scheme and demonstrate single-shot operation with a 113 x magnification factor, 1.5-ps resolution, and 220-ps record length.