Understanding Canon Lens abbreviations

You are almost there, just a click away from adding your Canon lens to the cart but WAIT! 
What happened? 
Why are you stepping back? 
Did you see those abbreviations (STM, USM, EF, L, zoom, etc) and got afraid as you're unaware?

Many of us have these questions,

"What do they mean?", 

"What exactly are they for?", 

"Are they really important?" 

Well today I am going to break it down for you and make you understand each and every abbreviation related to your Canon lenses so that at the end of the day you make a better and a smarter purchase.

Fig 1: The types of abbreviations 

Mount Type

The mount type decides the compatibility of the lens with the DSLR. The DSLRs have their own mount types which should match the one on the lenses, this assures secured and accurate means of connecting the lens to the camera body. Moreover, it enables an electronic communication between the lens and the DSLR to achieve precise focus and exposure.

• EF is fully electronic and covers a wide range of DSLR mounts. Originally launched in 1987, this still holds majority of the market and is compatible with all Canon EOS camera bodies.
• EF-S is a tad-bit advanced and covers the EOS models with a APS-C sensor. They shouldn't be connected to full frame bodies as that might damage the sensor of the DSLR body, which you should not want.
• EF-M is compatible with the mirrorless range as Canon has launched this specifically to support the EOS M camera bodies. Same as the EF and EF-S but they cannot be mounted with the DSLRs having the former mount types. Whereas the former mount types can be made compatible to work with EOS M mirrorless cameras if an apt lens adapter is used. 
• FD, FDn are other lens mount which are not in use these days as it was discontinued by Canon for lacking the auto-focus feature.

Focal Length

The focal length helps to decide how narrow or wide your frame will be by letting you zoom in/out. It can vary from 8mm to 600mm where 8mm is really wide rather fish eye and 600mm is too narrow rather a zoom lens. Based on it you can decide the genre of photography, whether its landscape, portrait, wildlife, event or macro. If you need to know more how focal length affects your photography then have a run through What lens you need.

E.g., 18-55mm, 24-105mm, 55-250mm, etc

Exposure

Exposure also known as the f-stop number or the aperture helps to decide the amount of light that's going to reach the sensor and the depth of field its going to produce while focusing an object in the frame. The lesser the number the more exposed will be the frame and the shallow will be the depth of field( I mean more blur to the background). Thus it lets you control the highlight-shadow ratio in the frame. To know more check What lens you need.

E.g., f/1.4, f/1.8, f/4, etc

L for Luxury

This tells you that the lens belongs to the Luxury range of Canon lenses which I would say are tailored made with more precise finishing. They are the top-end professional camera lenses that are equipped with better optical imaging and improved glass quality They are expensive and if you are a budget friendly person then they can cost you a lot and by a lot I mean starting from 50,000 give or take 5 grands and all the way to 2,00,000 give or take 10 grands.. They are easily identified by a red ring around the top which makes them different from other entry or mid-level lenses. 

Image Stabilization

IS or image stabilization is a new feature being introduced to the Canon lenses which enables you to take smooth and steady shot without shaky and blurred edges when shooting at low shutter speeds in low light conditions.

I, II, III

These Roman numbers are versions of the Canon lenses. II is the upgraded version of the lens with better image stabilization and optics and hence continues to III. Its newer, its better, its optimized and its been considered that whenever a lens gets an IS its upgraded from its predecessor.

Fig 2. I, II, III explained

Auto-focus motor (STM/USM)

The Canon lenses come with an auto focus motor that smooths up the entire paradigm of focusing, There is a confusion on which one is better, USM or STM? 

USM or ultra-sonic motor is a fast and receptive auto-focusing motor with less noise(sound) during operation. They mainly comprise the top end or the L series lenses as they are primarily used for photography. Because of which they need to be quick and spontaneous for changing subjects. So, that's professional all they way!

They do have a little squeaking sound which is noticeable in the videos. So, technically its not preferred for videos.

STM or stepper motor on the other hand is smooth and silent but a bit slow in focusing unlike the USM. They are preferred for shooting videos and are mainly found in the entry level and mid level Canon lenses. They use the fly by wire system where even if you manual focus by turning the ring the action will still be completed by the motor. 

Lens type

Based on the focal length the lenses are divided into 3 main types, namely wide angle, telephoto/zoom and prime. In Fig.1 its a zoom lens as the focal length can go all the way upto 105mm. Had there been no changing focal length then it would have wind up being a prime.

Plus if the focal length goes below 10mm then they are called fish eye lenses. If you need to know more on the classification of the lenses follow The Lens You Need.

So, on a conclusion a lens with IS and STM will give you smooth and less nosiy operation with sharp and stabilized images while a lens with L and USM initially will empty your pockets but later will give you a fast and responsive focusing with TASTY images. Thus, choose as per your need and budget.  

Cheers for now!