Incoherent digital holography (IDH) requires no spatial coherence; however, it requires high temporal coherence for a light source to capture holograms with high spatial resolution. Temporal coherence is often enhanced with a bandpass filter, reducing the light utilization efficiency. Thus, there is a trade-off between spatial resolution and light utilization efficiency. In this paper, we derive a relationship between spatial resolution and temporal coherence by including a conceptual aperture, determined by temporal coherence, in our previous theory of spatial resolution for arbitrary depth planes [Opt. Express27, 33634 (2019)OPEXFF1094-408710.1364/OE.27.033634]. Experimental evaluations verified the effectiveness of our theory, which is useful for the optimization of IDH setups and avoiding the trade-off.