Sunburn is a phenomenon which occurs when pixels are damaged, either temporarily or permanently, as a result of direct exposure to sun radiation. Consequently the image exhibits artifacts seen as white or black spots. In this study we investigate the effect of the F/# on sunburn in VOx bolometer. The experimental setup was designed to simulate sun radiation at flight conditions. We study the sunburn intensity, its recovery time and its dependence on F/#. As part of the data analysis, we used a SNR model to characterize the sunburn intensities. A good correlation was found between the SNR model and the naked eye observation of the sunburn spots.