When it comes to photographic styles for wedding photography, there is a common practice which many professionals employ that can prove problematic from a technical standpoint. While low aperture photography can certainly produce interestingly blurred backgrounds in portraiture, it is not something you want to use for an entire event, as moving subjects become difficult to capture and details end up becoming obscured. Furthermore, a low aperture should not be the go-to solution in low-light situations, since high ISO grain is easier to correct for than a blurry focal point. With a raw file, one is able to increase the luminosity of an image and thus blur together densely concentrated areas of grain. However, if an area is out-of-focus, there is no simple way to completely restore its detail. This is not to say that grain reduction is perfect, as it can result in overly smooth surfaces, but rather that it is more time efficient.
Perhaps unnoticeable when viewed at the small resolution above, the zoomed in versions below reveal first hand the effects of a high ISO or a low aperture. The first set offers a before and after glimpse of grain reduction, while the second set attempts to restore sharpness as best as possible. If nothing else, these images should at least make a case for avoiding low aperture settings for grouped subjects.