The Canon EF System: A Brief Overview

The Canon EF System: A Brief Overview

The Canon EF lens mount revolutionized the SLR world when it was released in 1987. The mount eschewed traditional mechanical control in favor of fully electronic and signaled a drastic shift in camera design. Metal, mechanical cameras were replaced with lighter, plastic models packed with electronics.

The mount was known for its wide opening (54mm, the largest at the time) and its short flange distance (44mm). The EF stands for Electro Focusing.

The EF system is one of the most popular and widespread systems worldwide for digital, but there are also plenty of options for film users as well as cinematographers and other use cases. That’s why we’re here to give you a brief overview of Canon EF. Here’s the video, scroll down further for the text version.

History & Overview

Canon introduced the EF system in 1987 with the EOS 650. From there, they quickly expanded their lineup with the EOS 1 professional body, showing their dedication to the direction the new mount would take them. And it truly was a new direction.

The EF mount would replace the long-running FD system, and would take things further than Canon was able to with that mechanical mount. By taking away all mechanical connection, Canon was able to put autofocus motors inside of each lens, making focus faster, quieter, and easier to implement on a lens-specific basis.

Where the FD mount was largely manual focus (with a few notable exceptions regarding the Canon T80) the Canon EF system is almost entirely autofocus. The exceptions include tilt & shift lenses and some third party manufacturers, like Cosina-built Carl Zeiss lenses.

Canon made a bold decision to completely abandon their old mount instead of modifying an old one for autofocus, like what Nikon or Pentax did. Fortunately, they recognized the potential weak points of that thought process, and the EF system outperformed most other autofocus systems for quite a while after release. 

This led to Canon SLRs becoming the industry standard for everyone from beginners to professionals, something that lasts to this day.

The EF system can be found everywhere from entry-level, crop-sensor cameras to professional sports SLRs and even high-grade, 4K movie cameras. This versatility is a big advantage of the system, as collecting lenses is especially worthwhile. Buying one Canon EF lens allows you to shoot stills on film and digital as well as film professional-grade movies. 

There is no other lens mount with this much flexibility and established user base. Canon even claims to have sold 100 million EF cameras by 2019.


Film Bodies

If you’re a Canon digital shooter, for photo or video, getting into film couldn’t be easier. There are quite a few popular Canon models that will handle very similarly to your current DSLR, just with film inside instead of a memory card. 

Canon EF bodies and lenses run the gamut from cheap to expensive, but have been mostly immune to the rising prices of film cameras in general. This leads to some cameras with impressive features being sold for far less than what they originally sold for. It also leads to them selling for far less than similar cameras from other manufacturers. 

For lower costs, something like the EOS 300 (also known as the EOS Kiss or the EOS Rebel 2000) would be a great choice, as many were made and prices are extraordinarily low considering the feature-set. The camera is also very small and lightweight due to its plastic construction.

If you want to move a bit up the ranks, the Canon EOS 30 (or EOS ELAN 7, EOS 7, etc.) is a great choice. The EOS 30 feels like a more professional camera with more substance behind it, and has access to multiple autofocus points. Some models have Canon’s eye-tracking focus, where the camera reads the photographer’s eye to decide which focusing point to use.

Even further up would be the Canon EOS 1 series. This flagship film camera was produced in some form from 1989 until 2018, and can be had for a fraction of what it sold for new. This is also, arguably, a fraction of what it deserves. 

Getting 3000€ of features for 500€ is a steal, and a great way for people with EF lenses to easily switch into film. 

It’s also great for people who might not feel as confident in their ability to manually expose. Whereas with a Pentax K1000 or similar mechanical SLR, the photographer is required to understand and know the rules right away, with a Canon EF SLR you can grow into photography. 

The plethora of automatic and semi-automatic modes makes it easy to learn what aperture, shutter speed, and ISO are and how they affect photos. Canon’s autofocus is also generally faster and more accurate than other manufacturers at the time.

Digital Bodies

Canon's digital bodies can be broken down into EF and EF-s models. We'll go into more detail on EF-s bodies in a later article, but all EF lenses will fit and work properly on the crop-sensor EF-s bodies.

The EF-s bodies generally represent the consumer grade, whereas the full EF bodies are more professional, featuring full-frame sensors, tougher bodies, and other high-end specifications.

The EOS D30 was the company's first DSLR, releasing in 2000 as a mid-range complement to the upcoming EOS 1-D. These early DSLRs will be the only models to feature crop sensors without using EF-s lenses.

Canon's DSLR bodies can be had cheaply by going a generation or two back. You may lose cutting-edge features, but you can save a bit of money and get an extremely capable camera.

One in particular that stands out is the original EOS 5D. This camera is more than enough for most applications, due to its full-frame sensor and excellent color rendition. Even with its age, it may be a better performer than a new entry-level camera at the same price.


Lens Types

In terms of lenses, Canon has produced so many lenses that prices of them remain low for the most part. A basic kit lens, around 28-80mm, will often be included with a camera body. A cheap 50mm lens can be purchased for under 100€, either from Canon or from another manufacturer like Yongnuo. Other primes are available cheaply as well, such as the 40mm f2.8 STM pancake lens.

Lenses can get more and more expensive, generally as they get newer, until you’re considering L lenses. These lenses represent the top of Canon’s offerings, and can be thousands of Euro. The photos, however, speak for themselves, and L lenses frequently show up on the secondhand market for fair prices. A lot of these lenses cover popular focal lengths, like 24-70mm, 100-300mm, etc. and feature advanced coatings and image stabilisation.

Lens stabilisation is a big benefit of using Canon’s EF system, especially on film. Finding true stabilisation on film is difficult, if not impossible, and is instantly noticeable when using a Canon lens. Especially for long telephoto lenses, like the 70-200mm f2.8 or f4, the difference is notable.

Notes on Lenses

Lens accessibility is second to only Nikon F, and Canon EF lenses can be found cheaply, even in good condition. Canon and other third party manufacturers continues to support EF despite the introduction of the RF mount. Companies like Tamron, Sigma, Carl Zeiss, and others make a wide variety of lenses for Canon EF.

Another advantage that might not be as obvious is the ability to adapt other lenses. With minimal effort, especially compared to Nikon, lenses from other manufacturers can be used on Canon EF bodies. Lens mounts like M42 and Nikon F will fit onto EF bodies as long as the proper adapter is used. This is possible due to wide diaphragm and short flange distance of the EF mount.

Be careful when picking a Canon EF digital body, however, because the EF-s mount slightly complicated things. EF-s lenses, introduced in 2002, are designed for APS-C sensors and thus won't cover 35mm film or a full-frame sensor. This gives them intense vignetting under all circumstances.

Note on Video

The popularity of the Canon EF system can also be credited with the widespread adoption of DSLRs for video production. The Canon 5D Mk ii in particular is an example of early high quality DSLR video. It had a full-frame sensor capable of recording video in full HD, in 2008, for 2300€.

By introducing video capabilities to their high-end, and eventually all of their DSLRs, Canon brought high-quality video to the masses. What once would cost 35,000€ could now be achieved with a tenth of that price.


Canon’s EF mount is one of the most popular and accessible lens mounts of all time. This keeps prices down and gives photographers a wide variety of options considering price and features. It’s comparably easy to gather a large collection of EF lenses. It's even easier to use them for multiple purposes, from shooting film to documentary filmmaking.

Aside from its versatility, Canon’s Electro-Focusing mount changed the world by showing the potential of an all-electronic lens mount. Others may have had electronics or autofocus first, but Canon was the first to fully commit to the digital future.

This article was originally published on 19.10.2020.

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