What is an RF Lens?

What is an RF Lens featured photo

If you are shopping for a new Canon lens, you probably come across different letters, such as RF and EF. These refer to the lens mount, which is an important buying consideration. Below, we will focus on the new technology of RF lenses.

An RF lens has an RF mount, which connects to the EOS R system. RF stands for Re-imagined Focus. It has a short flange focal distance and a wide diameter. These features enable RF lenses to deliver stunning optical performance.

A Canon RF lens offers several benefits, which we will cover in more detail below. This article will also answer your questions about this type of Canon lens.

What Is An RF Lens?

An RF Lens

An RF lens is a type of lens compatible with Canon’s mirrorless interchangeable cameras. Canon unveiled the RF mount lenses together with the EOS R cameras in 2018. 

The RF lens earned its name from Canon’s project R, which aimed to “Reimagine optical excellence.” Eventually, Canon used that letter for EOS R system cameras. The manufacturer also combined R with the existing EF or Electro-Focus lens. The result is the RF lens, which stands for “Re-imagined Focus.”

The Canon RF lens is characterized by a red line near the lens mount. It also features a short flange focal distance of 20mm. The flange back distance is the space between the lens mount (on the camera side) and the image sensor. A shorter back focus distance means improved optical performance and a more compact lens design.

Moreover, the RF lens system has a wide lens mount diameter of 54mm. It allows manufacturers to use larger glass elements on the rear end of the lens. These enable the light passing through the lens to bend less before hitting the sensor. Hence, it can minimize optical aberrations and produce better image quality.

How Does An RF Lens Differ From EF Lens? 

Below are the primary differences between an RF lens and an EF lens.

12-pin Connection

Differences Between an RF lens and an EF lens

First, the RF lens mount boasts a 12-pin connection between the camera and the lens. It has four more pins than the 8-pin configuration in the EF mount. 

The additional pins allow faster communication between the lens and camera body compared to Canon EF lenses. The RF lens can quickly control various settings, such as focus, aperture, zoom, shutter speed, and image stabilization.

More pins also mean larger bandwidth for data transfer. RF-mount lenses have built-in camera correction of optical aberrations. They even boast a real-time Digital Lens Optimizer (DLO) during continuous shooting. 

Finally, the 12-pin connection gives camera manufacturers the ability to add extra features later on. It is a way of future-proofing your lens system.

Focusing System

Thanks to its RF mount, a Canon RF lens offers a faster and more responsive autofocus system than EF lenses. It is compatible with new focusing technologies, such as the Dual Nano USM. As its name suggests, this technology uses two Nano USM motors to deliver faster, more efficient autofocusing performance.

Additionally, the RF camera lens minimizes the effects of focus breathing. It describes the slight movement in the focusing distance when you change the focal length. The lens takes advantage of floating focus groups and the latest technologies to prevent a change in the angle of view.

Plus, RF lenses have an electronic control ring and focus ring. Some models even offer both features. The former allows you to change the rotation direction and focus ring sensitivity. Meanwhile, the latter lets you use the focus ring to control the aperture, shutter speed, ISO, and other settings. 

Flange Distance

As previously mentioned, the RF lens has a shorter flange distance than Canon EF-mount lenses. The flange is the distance between the lens mount and the camera sensor. The shorter the distance, the closer the glass elements are to the image sensor. 

Canon RF lenses offer a 20mm flange back distance. A short gap is possible because RF lenses are designed for mirrorless cameras like the EOS R system. In contrast, EF lenses (used in DSLRs with a mirror) have a back focus distance of at least 44mm. Manufacturers must consider the design of the mirror in front of the image sensor, so they cannot make the flange shorter.

The shorter flange distance of the new RF-mount lenses allows for more lens design flexibility. Hence, manufacturers can design an RF lens with advanced optical elements for better image quality.

Size and Weight

Canon RF-mount camera lenses tend to be smaller and lighter than EF lenses. This is due to the shorter flange distance and optimized glass design. 

To put it into perspective, let us compare two popular zoom lenses: the Canon RF 70-200mm f/2.8L and the EF 70-200mm f/2.8L. The former is considerably lighter at 1070 grams compared to the latter, which weighs 1480 grams. The RF is also shorter in length (146mm) than the EF lens (199mm).

What Are The Advantages of Using a Canon RF Lens?

The newer Canon RF lens offers several benefits over the EF lens. Below are some key advantages of using Re-imagined Focus lenses.

Better Optical Quality

Canon RF lenses have advanced optical design and high image quality, thanks to their shorter flange distance. That means the internal glass elements are closer to the camera sensor. Hence, manufacturers can use a lens configuration with optimized image quality.

The RF lenses also have a wide mount diameter. They can fit larger lens elements near the sensor. Hence, they prevent light from bouncing too much and reduce chromatic aberrations, ultimately improving image quality.

Faster Autofocus Speed

Since RF lenses have a 12-pin connection, they deliver rapid communication between the lens and camera body. These lenses offer faster and more accurate autofocus. They can help you track a moving subject across the frame, which is ideal for action, sports, and event photography and videography. 

Enhanced Image Stabilization

Canon RF lenses also offer superior image stabilization (IS) technology. This feature can detect the slightest camera movement caused by your heartbeat or breathing. Then, it reduces that camera shake to help you capture sharper images. It is ideal when shooting at slower shutter speeds, in low-light environments, or in other challenging situations.

Compact and Lightweight Build

Another advantage of an RF camera lens is its small and lightweight build. The short flange back focus enables manufacturers to create a compact design without negatively affecting image quality.

The compactness of the RF lens is suitable for those who often travel. It is easy to carry and pack inside a bag when not in use.

Compatibility with Extenders and Future Technologies

A Canon RF lens has better compatibility with extenders. These camera accessories increase the effective focal length of a lens. They attach between the camera body and the lens. Extenders are ideal if you want to magnify the image. 

Despite their benefits, lens extenders are infamous for making image quality poor, especially when connected to EF lenses. Fortunately, RF-mount cameras and lenses offer better support for these accessories. That is because they have high-refraction, low-dispersion glass that reduces chromatic aberration.

The RF lens also uses the RF mount, which Canon recently developed. The manufacturing giant will release more cameras that use this particular mount. Hence, investing in Canon RF lenses opens up possibilities for future advancements in the industry.

Do Canon RF Lenses Fit Into An EF Mount?

While Canon RF lenses offer several benefits, they are incompatible with cameras that have an EF mount. These lenses are primarily designed for RF mounts found in Canon mirrorless systems. So even if they have the same diameter as EF lenses, RF lenses cannot fit into an EF mount.

However, if you have existing EF and EF-S lenses, you can attach them to Canon EOS R systems with an RF mount. Simply use EF-EOS R mount adapters.

Are RF Lenses More Expensive Than Other Types Of Lenses?

In general, Canon RF lenses tend to be more expensive than EF lenses due to several factors. First, RF lenses have a newer technology than EF ones. That means they use advanced optical elements and features, which contribute to high manufacturing prices. Another reason why they might be expensive is the high-quality materials they use. Moreover, RF lenses are still limited compared to the extensive lineup of EF lenses. Limited supply and higher demand for these lenses can increase their prices.

That said, the price of Canon RF lenses varies depending on focal length, aperture, and other qualities. They might also be worth considering for their advanced optical performance, solid build quality, and modern technology.


An RF lens is a type of lens designed for Canon EOS R system cameras. It has a wide diameter and short flange focal distance. It offers several benefits, like a fast 12-pin connection and better image quality. 

Do you have other questions about RF lenses? Drop by our contact page to send your queries!