Name Manufacturer / Model	Mount Bayonet	Type Category	Year Released	Focal mm	Aperture f/	Weight g
IrixBlackstone / Firefly 11mm F/4	CANON EF	Wide	2016	11mm	f/4	—
IrixBlackstone / Firefly 15mm F/2.4	CANON EF	Wide	2016	15mm	f/2.4	568g
IrixBlackstone 11mm F/4	CANON EF+ NIKON F, PENTAX K	Wide	—	11mm	f/4	—
IrixBlackstone 15mm F/2.4	CANON EF+ NIKON F, PENTAX K	Wide	—	15mm	f/2.4	—
Itorex50mm F/40 Pan Focus	T MOUNT	Prime	—	50mm	f/40	60g
Jupiter-21A 200mm F/4	T MOUNT	Telephoto	1968	200mm	f/4	740g
Jupiter-21M 200mm F/4	M42	Telephoto	1971	200mm	f/4	980g
Jupiter-37A 135mm F/3.5	T MOUNT	Telephoto	—	135mm	f/3.5	410g
Jupiter-37A 135mm F/3.5 [MC]	T MOUNT	Telephoto	—	135mm	f/3.5	410g
Jupiter-6-2 180mm F/2.8	M42	Telephoto	—	180mm	f/2.8	1470g
Jupiter-9 85mm F/2	M42+ CONTAX	Portrait	1951	85mm	f/2	360g
Jupiter-9 85mm F/2 [MC]	M42	Portrait	—	85mm	f/2	360g
Kaleinar-5N 100mm F/2.8 MC	NIKON F	Telephoto	1983	100mm	f/2.8	380g
Kalimar300mm F/5.6 Mirror	T MOUNT	Mirror	—	300mm	f/5.6	207g
Kamerabau-Anstalt-VaduzKilfitt-Makro-Kilar D 40mm F/3.5 C	M42	Macro	1955	40mm	f/3.5	145g
Kamerabau-Anstalt-VaduzKilfitt-Makro-Kilar E 40mm F/3.5 C	M42	Macro	1955	40mm	f/3.5	145g
Kase200mm F/5.6 Reflex SLR	CANON EF	Mirror	2024	200mm	f/5.6	384g
Kelda500mm F/6.3 Mirror DX	T MOUNT	Mirror	—	500mm	f/6.3	597g
Kelda6.5mm F/3.5 ASPH Fisheye CS	CANON EF	Fisheye	—	6mm	f/3.5	516g
Kelda8mm F/3.5 Fisheye CS	CANON EF	Fisheye	—	8mm	f/3.5	516g
Kenko35mm F/4 Soft MC	T MOUNT	Wide	1996	35mm	f/4	—
Kenko400mm F/8 Mirror MC	T MOUNT	Mirror	2012	400mm	f/8	340g
Kenko400mm F/8 Mirror MC N II	T MOUNT	Mirror	2017	400mm	f/8	500g
Kenko400mm F/8 Mirror MC N II S	T MOUNT	Mirror	2021	400mm	f/8	500g
Kenko45mm F/4.5 Soft MC	T MOUNT	Prime	1995	45mm	f/4.5	210g
Kenko85mm F/2.5 Soft MC	T MOUNT	Telephoto	1987	85mm	f/2.5	340g
KenkoMIL TOL 200mm F/4	T MOUNT	Telephoto	2015	200mm	f/4	670g
KenkoMIL TOL 400mm F/6.7 ED	T MOUNT	Telephoto	2015	400mm	f/6.7	1560g