Through targeted fine-tuning of the lens construction, this lens has been designed to create a unique visual effect known as "Rainbow Flare" when shooting with a wide aperture (up to F4) and strong backlighting. By changing the composition or the position relative to the light source, the photographer can influence the position and size of the effect. When mounted on an APS-C format digital SLR camera, it can be challenging to produce rainbow flares, as the camera's image sensor is designed to utilize only the central area of the lens's image circle. By stopping down to F4 or lower, the photographer can capture sharp, clear, and brilliant images—free from the "Rainbow Flare" effect—that are not only devoid of rainbow flare but also free from ordinary flare and ghosting. To utilize the "Rainbow Flare" effect even in bright lighting conditions at wide apertures, it is recommended to use a commercially available ND (Neutral Density) filter that reduces light transmission. An ND16 filter, which reduces light transmission to less than 1/16, is included with this lens.