Figuring out the difference between an RF lens and an RF-S lens can feel a bit confusing when you’re just starting out with your Canon camera. It’s a common question, and we’re here to make it super easy to grasp. Think of this as your straightforward guide to understanding exactly what each type of lens is for.
We’ll break it down step by step so you know which lens is the right pick for your photos. Get ready to clear up any confusion about the rf vs rf-s lens debate.
Understanding RF and RF-S Lenses
Canon’s mirrorless camera system uses the RF mount, which is a modern and powerful mount designed for excellent image quality and autofocus performance. Within this system, there are two main types of lenses you’ll encounter: RF lenses and RF-S lenses. The distinction between them is primarily related to the sensor size of the camera they are designed to be used with. This is the key factor that influences their size, weight, price, and the resulting image field of view.
What Are RF Lenses
RF lenses are Canon’s full-frame lenses. This means they are designed to cover the entire image sensor of a full-frame camera. Full-frame cameras have a sensor that is roughly the same size as a 35mm film frame (approximately 36mm x 24mm). When you mount an RF lens on a full-frame EOS R series camera, you get the full potential of both the lens and the camera’s sensor.
The advantages of RF lenses include:
- Superior image quality due to covering a larger sensor.
- Often have wider maximum apertures, which are good for low light and creating blurry backgrounds.
- Generally offer higher optical performance and build quality.
- A wider selection of professional-grade lenses available.
Because they are designed for a larger sensor, RF lenses are typically larger, heavier, and more expensive than their RF-S counterparts. They are built to capture the highest possible detail and produce the best possible images, making them a favorite among professional photographers and serious enthusiasts.
What Are RF-S Lenses
RF-S lenses, on the other hand, are designed specifically for Canon’s APS-C sensor mirrorless cameras that also use the RF mount. APS-C sensors are smaller than full-frame sensors. When you mount an RF-S lens on an APS-C EOS R series camera, it covers the entire APS-C sensor.
The key characteristics of RF-S lenses are:
- Designed to match the smaller size of APS-C sensors.
- Generally more compact, lighter, and more affordable.
- Offer excellent image quality for their intended use.
- Often designed with specific focal lengths and features suited for everyday photography and travel.
The “S” in RF-S stands for “Small” or “Standard,” highlighting their more compact design and often more accessible price point. These lenses are a fantastic option for photographers who own or are considering an APS-C EOS R camera.
Compatibility: RF Lenses on APS-C Cameras
This is where things can get a little interesting, and often a source of confusion. When you mount an RF lens (designed for full-frame) onto an APS-C EOS R camera, the camera automatically recognizes that it’s on a smaller sensor.
Here’s what happens:
- Cropping: The camera will engage a crop mode. This means only the central portion of the RF lens’s image circle is used to cover the APS-C sensor. Effectively, the camera uses the equivalent of a smaller sensor area.
- Focal Length Multiplier: Because the APS-C sensor is smaller, it captures a narrower field of view compared to what the same lens would capture on a full-frame camera. This is often referred to as a “crop factor.” For Canon APS-C cameras, this crop factor is typically 1.6x. So, a 50mm RF lens on an APS-C camera will give you a field of view similar to an 80mm lens on a full-frame camera (50mm x 1.6 = 80mm).
- Image Quality: While the image quality is generally still very good, you are not utilizing the full optical capabilities of the RF lens. You’re essentially using only the central, often optically superior, part of the image circle.
- Autofocus and Performance: RF lenses perform excellently on APS-C bodies. They offer the same fast and accurate autofocus and image stabilization as they would on full-frame cameras.
So, can you use RF lenses on APS-C cameras? Yes, absolutely. They work perfectly fine. However, it’s important to be aware of the crop factor and that you’re not using the lens to its maximum potential in terms of image circle coverage.
Compatibility: RF-S Lenses on Full-Frame Cameras
Now, let’s look at the reverse situation. What happens when you mount an RF-S lens (designed for APS-C) onto a full-frame EOS R camera?
The answer is: the camera will not cover the full-frame sensor.
When an RF-S lens is mounted on a full-frame EOS R camera, the camera will detect that the lens’s image circle is too small to cover the entire full-frame sensor. To prevent severe vignetting (dark corners) and image distortion, the camera will automatically activate its APS-C crop mode.
This means:
- Automatic Cropping: The full-frame camera will essentially behave like an APS-C camera, only using the central portion of its sensor.
- Focal Length: The focal length effectively becomes the stated focal length multiplied by the 1.6x crop factor, just as if you were using the lens on a native APS-C body.
- Resolution: The resolution of your images will be limited to that of the cropped APS-C area.
- Usefulness: While technically functional, using an RF-S lens on a full-frame camera is generally not recommended if your goal is to achieve the full benefits of a full-frame sensor. It’s essentially using a smaller lens on a larger sensor and getting the results of the smaller sensor.
So, while you can mount an RF-S lens on a full-frame camera, it’s not an ideal pairing if you want to capture images that utilize the full resolution and wider field of view of your full-frame sensor.
Key Differences Summarized
Let’s put the main distinctions between RF and RF-S lenses side-by-side to make it very clear.
| Feature | RF Lenses | RF-S Lenses |
|---|---|---|
| Sensor Size Designed For | Full-Frame (36x24mm) | APS-C (smaller than full-frame) |
| Image Circle Coverage | Covers entire full-frame sensor | Covers entire APS-C sensor |
| Performance on Full-Frame Body | Native, optimal performance | Auto-crops to APS-C mode, limited coverage |
| Performance on APS-C Body | Auto-crops to APS-C mode (uses central part of image circle) | Native, optimal performance |
| Typical Size and Weight | Larger and heavier | Smaller and lighter |
| Typical Price | More expensive | More affordable |
| Optical Design Philosophy | Maximizing image quality for full-frame | Optimized for APS-C, often prioritizing size/cost |
| Field of View on Native Body | Wider (for a given focal length) | Narrower (for a given focal length, due to crop factor) |
This table should help visualize the core differences. When choosing a lens, always consider the sensor size of the camera you are using or plan to use.
Choosing the Right Lens for You
So, how do you decide which type of lens is best for your needs? It really comes down to the camera you own and the kind of photography you do.
If You Have a Full-Frame EOS R Camera:
- Your Best Bet: RF lenses. These are designed to work with your camera’s sensor to give you the best possible image quality, widest field of view, and optimal performance.
- Can You Use RF-S Lenses? Yes, but it’s like putting a smaller picture frame on a large wall. The camera will crop, and you won’t get the full advantage of your full-frame sensor. It might be okay in a pinch for a specific focal length, but it’s not ideal for everyday shooting if you want to leverage your full-frame capabilities.
If You Have an APS-C EOS R Camera:
- Your Best Bet: RF-S lenses. They are designed to perfectly match your APS-C sensor. They offer great performance, are often more compact and affordable, and give you the true focal length without any cropping surprises.
- Can You Use RF Lenses? Yes, and they will work well, providing excellent image quality. However, remember that the camera will crop the image to match the APS-C sensor. This means a 50mm RF lens will behave like an 80mm lens. You’re essentially using the center part of the RF lens’s image. This can be useful if you need a longer reach, but it’s not utilizing the full lens or camera sensor.
When to Consider RF-S Lenses for Full-Frame
While generally not recommended as the primary choice for full-frame users, there are a few niche situations where an RF-S lens might be considered on a full-frame body:
- Budget Constraints: If you need a specific focal length and an RF-S lens is significantly cheaper than an RF equivalent, and you’re okay with the crop, it might be a temporary solution.
- Portability: If you are prioritizing the absolute smallest and lightest kit possible, and the cropped field of view is acceptable for your subject matter, an RF-S lens could be an option.
- Specific Focal Length Needs: Perhaps you need a super-telephoto reach. Using an RF-S lens on a full-frame body and benefiting from the crop factor can give you effectively longer focal lengths than you might get with some RF lenses.
However, for most full-frame shooters, investing in RF lenses will yield the best results and a more satisfying shooting experience.
When to Consider RF Lenses for APS-C
Using RF lenses on APS-C cameras is very common and often a great choice, especially if you plan to upgrade to a full-frame camera in the future.
- Future-Proofing: If you’re an APS-C shooter with an eye on moving to full-frame later, buying RF lenses now means they will still be perfectly compatible and perform optimally with your future full-frame body.
- Optical Quality: RF lenses are often built with the highest optical standards. Even when cropped, they can deliver superb image sharpness and detail.
- Wider Apertures and Faster Lenses: If you need very wide apertures (like f/1.2 or f/1.4) or specialized lenses (like tilt-shift or super-telephotos) that are not yet available in RF-S, you’ll likely need to look at RF options.
- Focal Length Flexibility: The crop factor of APS-C cameras can turn a standard 50mm RF lens into a great portrait lens (around 80mm equivalent), or a wider 35mm RF lens into a fantastic standard perspective lens (around 56mm equivalent).
The main thing to remember is that the effective focal length will be longer due to the crop factor.
Common Scenarios
Let’s imagine a few everyday photography situations to illustrate.
Scenario 1: Travel Photography
Imagine you’re going on a trip and want a versatile lens.
- With an APS-C camera: An RF-S 18-45mm f/4.5-6.3 IS STM lens would be a great, compact, and affordable choice. It offers a versatile zoom range equivalent to about 29-72mm on full-frame, perfect for landscapes, street shots, and general sightseeing.
- With a full-frame camera: An RF 24-105mm f/4 L IS USM lens would be ideal. This is a more robust, professional-grade lens that covers a wider range of situations without cropping. If you put an RF-S lens on this full-frame camera, it would crop down to a narrower field of view, similar to what the APS-C user is getting with their native lens, but with less resolution from the full-frame sensor.
Scenario 2: Portrait Photography
You want to take portraits with a nicely blurred background.
- With an APS-C camera: An RF 50mm f/1.8 STM lens is a popular choice. On APS-C, this becomes equivalent to an 80mm lens, which is a classic portrait focal length. The f/1.8 aperture helps create that desirable bokeh.
- With a full-frame camera: The same RF 50mm f/1.8 STM lens would provide a true 50mm field of view, great for environmental portraits. If you used an RF-S lens on this camera, it would crop in significantly, giving you an even longer effective focal length, potentially too long for many standard portrait shots.
Scenario 3: Landscape Photography
You want to capture sweeping vistas.
- With an APS-C camera: An RF-S 10-18mm f/4.5-6.3 IS STM lens is designed for this. On APS-C, it provides an equivalent wide-angle range of about 16-29mm, perfect for capturing expansive scenes.
- With a full-frame camera: An RF 15-35mm f/2.8 L IS USM lens is a professional-grade ultra-wide zoom. It offers a significantly wider field of view than the RF-S lens on APS-C. If you put the RF-S 10-18mm on a full-frame camera, it would only capture a small central portion of the image, essentially giving you a much narrower field of view than intended, and likely with heavy vignetting if the camera didn’t crop it.
Frequently Asked Questions
Question: Can I use any RF-S lens on a full-frame Canon EOS R camera
Answer: Yes, you can physically mount RF-S lenses on full-frame EOS R cameras. However, the camera will automatically engage a crop mode because the RF-S lens’s image circle is too small to cover the entire full-frame sensor. This means you will only use the central part of the sensor, and your images will have reduced resolution and a narrower field of view, as if you were using an APS-C camera.
Question: Will my RF-S lenses work on a Canon EOS R7 or R10
Answer: Yes, RF-S lenses are designed specifically for Canon’s APS-C EOS R series cameras like the EOS R7 and EOS R10. They will provide optimal coverage, performance, and image quality for these camera bodies.
Question: If I put an RF lens on an APS-C EOS R camera, is the image quality worse
Answer: The image quality is generally still very good. RF lenses are optically superior, and the APS-C camera uses the central, often the sharpest, part of the RF lens’s image circle. However, you are not utilizing the lens’s ability to cover a full-frame sensor, and the effective focal length will be multiplied by the crop factor.
Question: Are RF-S lenses cheaper than RF lenses
Answer: In general, yes. RF-S lenses are typically more affordable than their RF counterparts. This is because they are designed for smaller sensors, which often allows for simpler optical designs, smaller physical sizes, and less expensive materials and construction.
Question: If I buy RF lenses, can I use them on both full-frame and APS-C EOS R cameras
Answer: Yes, RF lenses are fully compatible with both full-frame and APS-C EOS R cameras. On a full-frame camera, they cover the entire sensor. On an APS-C camera, they will be cropped, and the effective focal length will be multiplied by the camera’s crop factor (usually 1.6x for Canon APS-C).
Final Thoughts
When you’re trying to figure out the rf vs rf-s lens situation, the main thing to remember is the sensor size of your camera. RF lenses are for full-frame cameras, designed to capture the biggest, most detailed images. RF-S lenses are made for APS-C cameras, offering a more compact and often more budget-friendly option that perfectly fits those smaller sensors. You can absolutely use RF lenses on APS-C cameras, but the camera will crop in, effectively making the lens’s focal length longer. On the flip side, using RF-S lenses on a full-frame camera also results in a crop, and you’re not getting the full potential of your camera. Think about your current camera and your future plans. If you have an APS-C and might go full-frame later, investing in RF lenses now is a smart move that pays off. If you’re happy with your APS-C and want something lightweight and affordable, RF-S lenses are fantastic. Either way, Canon’s RF mount offers a great system for capturing your world, and knowing these lens types helps you make the best choice for your photography.
