Notes										
										
Mount										
	Lens Mount	Description	Fits							
	EF	Standard EOS mount	All EOS cameras including those with EF-S mounts							
	EF-S	Short back-focus EOS mount	Digital EOS SLR's with 1.6 crop factor & EF-S Mount - currently 300D/D-Rebel & 20D only							
										
L / DO										
	Designation	Description	Notes							
	L	"""L"" Class lens"	"""Luxury"" or Professional Lens. Contain Flourite &/or Ultra-Low Dispersion Glass Lenses"							
	DO	Diffractive Optics	New optical technology that allows shorter and lighter telephoto lenses							
										
Autofocus Motor										
	Designation	Description	Notes							
	AFD	Arc Form Drive	Original EF Lens motor - compact but slower and noisier than USM lenses							
	MM	Micro-Motor	"Compact cheap motor typically fitted to ""consumer"" lenses"							
	USM	UltraSonic Motor 	Ring-type USM lens - the fastest quietest AF motor with benefit of Full-Time Manual focus (see below)							
	Micro-USM	Micro-USM Motor	Cheaper form of USM (using micro-motor rather than USM Ring)							
			Still quiet but not as fast and does not generally provide FTM.							
			Mark II version of Micro-USM introduced in 2003							
Manual Focus										
	Designation	Description	Notes							
	AF	Auto Focus only	A small number of early EF lenses do not have any manual focus capability							
	DIS	Manual Focus is disengaged in AF-mode	When AF is selected on the lens switch then the manual focusing ring spins freely without effect.							
			"To use Manual Focus must move switch to ""MF"" or ""M"" position"							
	EM	Electronic Manual Focus	The manual focus ring is active at all times - even during Autofocus; allows manual fine tuning of focus							
			without switching to MF mode. Works very well for users who use CF-4 to transfer AF to the *-button.							
			When the focus ring is turned this is sensed and transferred electronically to the focus motors in the lens.							
	FTM	Full-Time Manual	The manual focus ring is active at all times - even during Autofocus; allows manual fine tuning of focus							
			without switching to MF mode. Works very well for users who use CF-4 to transfer AF to the *-button.							
	LOCK	Manual focus locked in AF-mode	In AF-mode the manual focus ring cannot be turned (and damage may result if attempted).							
			"To use Manual Focus must move switch to ""MF"" or ""M"" position"							
	MF	Manual Focus only	No AF capability. Manual Focus always available.							
										
Lens Hoods										
	Lens hoods have designation in form such as EW-83B/2 or ET-60 II where:									
	EW =	EF Wideangle lens								
	ES =	EF Standard lens								
	ET =	EF Telephoto lens								
	Number (e.g. 83 or 60) is lens hood mount diameter									
	Variant (e.g. B) is the variety (not always present) - this is important an 83E Hood will either not fit or not workcorrectly with a lens designated 83F 									
	Mark (e.g. /2 or II) is the release version (not always present) - differences are minor (e.g. improved flocking) and do not affect which hood works with which lens									
	"(note: in this table I have omitted ""/2"" or ""II"" type suffixes)"									
										
	Occasionally a different hood will fit and is more appropriate when using a lens on a 1.6 crop DSLR - e.g the EW-83D is more effective and more									
	convenient than the EW-83E Hood provided with the 17-40f4 L lens when using that lens on a D30 / D60 / 10D / 20D or 300D/D-Rebel									
	Note: just because hood has the same diameter mount as a lens's standard hood does not necessarily mean it will physically fit!									
										
Filter										
	nn	Screw in front mounted filter of nn mm diameter								
	(di)	Drop-in filter. Used in fast telephoto lenses that have very large front elements that make front mounted filters impracticable								
										
Filter Rotation										
	NR	Filter does not rotate during focussing								
	Rot	Filter rotates during focussing								
										
Image Stabilisation										
	Designation	Hand-Held Stops Gain								
	2-	2-stops benefit								
	3-	3 stops benefit								
	4-	4 stops benefit								
	M1	Mode 1: Normal use								
	M2	Mode 2: Use when panning								
	MAP	Automatically detects and adjusts for panning 								
	TD	Detects use of tripod and auto adjusts IS operation								
										
Focus Type										
	I/R	Internal or rear lens group moves	Lens does not extend during focusing							
	Linear Ext	Linear Extension	Lens extends during focusing							
										
Tripod Mount										
	TMR-A	Tripod Mount Ring A	Comes in black and white versions							
	TMR-B	Tripod Mount Ring B	Black version only							
	TMR-B + Ad	Tripod Mount Ring B + Adapter	Adapter enables use on 100mm f2.8 Macro lens							
										
Distance Scale										
	Y	Distance Scale provided								
	MS	Magnification Scale	Provided on macro lenses to show image magnification factor							
	TS	Tilt / Shift	Tilt / Shift markings							
										
E-TTL II Distance										
	Y	Distance Information is provided	The E-TTL II system uses the subject distance (if available from the lens) to improve flash exposure							
	Note: This data is provisional as it is unclear for some lenses as to whether they support this or not									
										
Macro										
	"""Macro"" here means true macro not simply a lens that will close focus."									
	"Purists might say it has to go to life-size (i.e. 1:1) to be a ""macro"" lens but we accept the 50mm f2.5 Compact Macro as a "									
	true macro lens even though it only goes to 1:2 (unless you use the life-size convertor) because it is optimised for close									
	working / macro use.