The Imaging mode of NIRISS makes use of flight spare filters from NIRCam and is an integral part of observing in the WFSS mode. In general, NIRCam is the camera of choice for near-infrared imaging with JWST, since it has twice the field of view of NIRISS and obtains "blue" and "red" images simultaneously. Nevertheless, if used in parallel with NIRCam during programs involving deep imaging, NIRISS would provide a third near-infrared imaging channel with matched filters. The resultant gain in sky coverage would be realized if, at some point in the future, it is decided that JWST should support parallel science observations.
The-wide band filters in the Pupil Wheel (highlighted in green) may be used only with the Filter Wheel in the CLEAR position (highlighted in green), as shown in Figure 1. The wide-band filters in the Filter Wheel (highlighted in green) may be used only with the Pupil Wheel in the CLEARP position (highlighted in green), as shown in Figure 2.