Name Manufacturer / Model	Mount Bayonet	Type Category	Year Released	Focal mm	Aperture f/	Weight g
Helios-81N 50mm F/2 MC	NIKON F	Portrait	1978	50mm	f/2	215g
HugoMeyer Gorlitz Makro-PLASMAT 50mm F/2.7 For Kine-Exakta	EXAKTA	Prime	—	50mm	f/2.7	—
IhageeAnastigmat Exaktar 54mm F/3.5	EXAKTA	Prime	—	54mm	f/3.5	—
Industar-50-2 50mm F/3.5	M42	Prime	—	50mm	f/3.5	75g
Industar-61 L/Z 50mm F/2.8	M42	Prime	—	50mm	f/2.8	225g
Industar-61 L/Z 50mm F/2.8 [MC]	M42	Prime	—	50mm	f/2.8	225g
Industar-61M 50mm F/2.8	M42	Prime	1971	50mm	f/2.8	250g
Irix11mm F/4	CANON EF+ CANON EF-S, NIKON F, NIKON F DX, PENTAX K	Wide	2017	11mm	f/4	847g
Irix150mm F/2.8 Macro SLR	CANON EF	Macro	2018	150mm	f/2.8	848g
Irix15mm F/2.4	CANON EF+ CANON EF-S, NIKON F, NIKON F DX, PENTAX K, SONY E	Wide	2016	15mm	f/2.4	568g
Irix15mm F/2.4 Dragonfly	SONY E+ SONY FE	Wide	—	15mm	f/2.4	662g
Irix21mm F/1.4	CANON EF	Wide	2022	21mm	f/1.4	830g
Irix30mm F/1.4	CANON EF	Wide	2021	30mm	f/1.4	863g
Irix45mm F/1.4	CANON EF+ CANON EF-S, NIKON F, NIKON F DX, PENTAX K	Prime	2020	45mm	f/1.4	925g
Irix45mm F/1.4 GFX	FUJIFILM G	Prime	2021	45mm	f/1.4	1120g
Irix45mm F/1.4 SLR	CANON EF	Prime	2020	45mm	f/1.4	925g
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	—
Isco-GottingenISCONAR 100mm F/4 Type 1	EXAKTA	Telephoto	—	100mm	f/4	—
Isco-GottingenISCONAR 100mm F/4 Type 2	EXAKTA	Telephoto	1964	100mm	f/4	—
Isco-GottingenISCONAR 100mm F/4.5	EXAKTA	Telephoto	1956	100mm	f/4.5	—
Isco-GottingenISCONAR 135mm F/4 Type 1	EXAKTA	Telephoto	—	135mm	f/4	—
Isco-GottingenISCONAR 135mm F/4 Type 2	EXAKTA	Telephoto	1959	135mm	f/4	—
Isco-GottingenISCONAR 135mm F/4 Type 3	EXAKTA	Telephoto	1964	135mm	f/4	—
Isco-GottingenISCONAR 50mm F/2.8	EXAKTA	Prime	1955	50mm	f/2.8	—
Isco-GottingenISCOTAR 50mm F/2.8 Type 2	EXAKTA	Prime	1963	50mm	f/2.8	—