The parameters of the spectrometer were analyzed in order to optimize the performance of spectral-domain optical coherence tomography (SD-OCT). Because probing depth is proportional to spectral resolution, it can be increased with the choice of a higher resolution spectrometer, which implies greater pixel numbers and lower imaging speed, or by sacrificing part of the spectrum, which compromises the axial resolution and side lobes. With a dynamic range of 8 bits or more, the signal-to-noise ratio remains constant for different noise levels. The results were verified experimentally with in vivo retinal SD-OCT imaging.