Promising, net-zero fuels such as ammonia and hydrogen present slow burning and associated challenges when employed in established spark-ignition engines. This article describes visualization of spark-ignited, premixed, turbulent flames accelerating in a constant-volume chamber. Pressure-based measurements of combustion emphasize the later stages of the combustion process and provide a poor measure of the early flame development. Direct photographic studies are limited by the low light emission from the flames, giving poorly defined flame images. In contrast, basic schlieren photography produces a clear, sharp-edged flame contour, enabling accurate estimation of the flame growth rate. Moreover, the schlieren image exposes the progressive effects of turbulence in wrinkling and distorting the flame. This furnishes additional information for a better understanding of nature and degree of flame surface enhancement by continuous turbulent wrinkling and distortion. A high-speed video system using the schlieren technique was used to record flame growth at 2000 frames per second following spark ignition of propane-air and methane-air mixtures in a transparent combustion cell. The results are compared with a high-speed direct video and high-speed direct film cinematography under the same conditions. Schlieren photography can enhance and complement pressure-based analysis, to further development of clean, slow-burning fuels such as ammonia. It can provide important details on early flame development and the efficacy of ignition strategies, mixture stratifications, and cycle-to-cycle variations.