Abstract: An accessory cartridge for removable reception in a specialized lighting fixture. A circular cartridge ring is provided with an internal lower flange, for supporting one or more flat, circular, disc-like accessory elements, such as filters. Retainer clips are positioned to engage at least the uppermost one of the disc-like accessory elements, such that one or more of the disc-like accessory elements may be easily installed within the cartridge ring and the entire series thereof automatically retained therein by engagement of at least the uppermost accessory element. The entire cartridge is designed to be bodily installed in or removed from the lighting fixture, to facilitate expeditious changing of accessory elements utilized with the lighting fixture. Preferentially, the lighting fixture is provided with a hingedly connected front barrel portion, which is constructed to receive and support the cartridge.