Expert view: when is a bigger sensor better? Full-frame cameras explained

In the first in a series of technical explainers by Canon specialists, Canon Europe Product Marketing Manager John Maurice explores some of the issues to consider when deciding whether to make the move to a full-frame camera system.
The interior of a flooded cave with thousands of stalactites illuminated by blue lights.

It's one of the most common questions photographers ask: should I make the move to full-frame and, if I do, which camera should I go for? Like many people, I started with an APS-C DSLR camera and progressed through to full-frame. Because I like to thoroughly research any piece of equipment I'm considering, each camera purchase required some pause for thought, digging into the technical elements and whether it would benefit my photography.

With the benefit of hindsight, and many years spent working on Canon's camera range, I've broken that down into a simple guide, so you can decide for yourself whether the move to full-frame is right for you.

John Maurice is Product Marketing Manager at Canon Europe. He started his career with Canon in 2008 as a camera specialist and now leads the product technical team. He's also an active photographer, with a particular interest in photographing nature and the outdoors. John's first film camera was the Canon T70 and his first digital SLR was the Canon EOS 300D.
A woman in a leather jacket sits in a darkened room, her face partially lit by natural light from the window behind her.

The full-frame format will give you more options when light levels prove challenging. Taken on a Canon EOS RP with a Canon RF 24-105mm F4L IS USM lens at 27mm, 1/500 sec, f/4 and ISO1600.

Are full-frame cameras better?

Moving to a full-frame camera has many well-documented benefits. The larger image sensor generally allows for better performance in low-light conditions, which will be an advantage if you shoot interiors, weddings, indoor portraits or events, for example.

Below is an illustrative example of a night-time city scene, the left-hand image taken with the APS-C based Canon EOS 80D (now succeeded by the EOS 90D) and the right-hand image with the full-frame Canon EOS RP. As you can see, the appearance of image noise is lower and the detail higher in the EOS RP image. This is the kind of result you would see if you step up from an older APS-C camera.

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Two office buildings at night, with lights on in the windows.

A crop of a night scene shot on a Canon EOS 80D. The EOS 80D's APS-C sensor is smaller than a full-frame sensor, which means it captures less image detail in low light conditions. Taken on a Canon EOS 80D with a Canon EF 70-200mm f/4L IS II USM lens at 70mm, 1/8 sec, f/5.6 and ISO6400.

Two office buildings at night, with lights on in the windows.

A crop from an almost identical image taken on a full-frame mirrorless EOS RP. Viewing the images side by side illustrates the differing levels of image noise. Taken on a Canon EOS RP with a Canon EF 70-200mm f/4L IS II USM lens at 113mm, 1/8 sec, f/5.6 and ISO6400.

Another aspect to consider is the shallower depth of field that is possible with a full-frame camera when the framing is the same. This will be of benefit if you want a more artistic look, or greater subject isolation as a result of the more extreme background blur.

Branches of a dead tree with snow-capped mountains in the background.

This image and the one next to it are both framed in the same way, but the APS-C sensor in the EOS 80D does not produce the same fall-off in focus as the full-frame EOS RP. Taken on a Canon EOS 80D with a Canon EF 70-200mm f/4L IS II USM lens at 70mm, 1/1250 sec, f/4 and ISO100.

An almost identical image of the same branches, with the mountains in the background slightly more blurred.

Cameras with full-frame sensors are generally capable of shallower depth of field, so that foreground objects stand out more against the blurred background. Taken on a Canon EOS RP with a Canon EF 70-200mm f/4L IS II USM lens at 110mm, 1/1250 sec, f/4 and ISO100.

Often a full-frame camera will give you greater flexibility when it comes to shadow or highlight recovery compared to older APS-C models – a benefit for scenes that include a wide tonal range, such as landscapes, portraits, fashion and interiors.

A woman seated at a table on a padded, rainbow-striped bench, with the shadow of the window frame filling the wall behind her.

I've found that having a small full-frame camera and a compact lens is a benefit when taking snapshots of everyday life. Taken on a Canon EOS RP with a Canon RF 35mm F1.8 Macro IS STM lens at 35mm, 1/4000 sec, f/1.8 and ISO400.

The evening sky is reflected in a series of glass-panelled buildings.

It is often possible to recover more detail in shadows and highlights in images from a full-frame camera. For this reason, full-frame is often considered to be the best choice for landscape and cityscape photography. Taken on a Canon EOS RP with a Canon RF 24-105mm F4L IS USM lens at 85mm, 1/40 sec, f/5.6 and ISO1600.

Which full-frame camera should you choose?

The answer depends on what you need from your camera. Entry-level full-frame models – whether they're DSLRs such as the Canon EOS 6D Mark II or full-frame mirrorless cameras such as the Canon EOS RP – focus on portability and, thanks to their easy interface and touchscreen controls, remain as simple to use as an APS-C camera.

You might think the move to full-frame has some serious weight implications, but while that may have been true in the past, it's no longer the case. In fact, the absence of a mirror and optical viewfinder assembly means that full-frame mirrorless cameras can be made smaller than APS-C DSLRs. Take the example of a move from an older APS-C DSLR to a full-frame mirrorless EOS RP:

Canon EOS 700D Canon EOS RP
Body weight (including battery and card): 580g Body weight (including battery and card): 485g
Paired with its standard lens, Canon EF-S 18-55mm f/3.5-5.6 IS STM (200g) Paired with its standard lens, Canon RF 24-105mm F4-7.1 IS STM (375g)
Total weight: 780g Total weight: 880g

The full-frame kit is just 100g heavier than the APS-C DSLR, and the RF 24-105mm F4-7.1 IS STM lens will provide greater range, alongside the full-frame camera benefits already mentioned.

If you are used to the speed of an advanced APS-C camera, then models higher up the range, such as the Canon EOS R6 (which offers up to 20fps), will be a step up in quality and speed. However, you have to bear in mind that your lenses will not provide the same reach as they do on an APS-C body, because the crop factor of an APS-C sensor makes the subject larger in the frame – see the section on lenses below for more about this.

A Canon EF-S 18-55mm f/3.5-5.6 IS STM lens.

Many photographers start their journey with a lens such as the Canon EF-S 18-55mm f/3.5-5.6 IS STM.

A Canon RF 24-105mm F4-7.1 IS STM lens

When making the move to full-frame, having a versatile lens such as the Canon RF 24-105mm F4-7.1 IS STM in your kitbag will enable you to cover most scenarios.

What about lenses?

First consider which types of lenses you most enjoy using on your current camera, and check whether they will be compatible with a full-frame camera. Will they work in the same way? Lenses can change their character as you move across formats.

If you have a Canon EF-S 18-55mm f/3.5-5.6 IS STM or EF-S 18-135mm f/3.5-5.6 IS STM lens (considered "general-purpose" APS-C lenses) then the equivalent lens for a full-frame mirrorless camera would be a zoom such as the Canon RF 24-105mm F4-7.1 IS STM, which is also a general-purpose lens providing wide-angle and telephoto all in one.

If you have a two-lens combination, such as a general EF-S 18-55mm lens plus a telephoto EF-S 55-250mm f/4-5.6 IS STM lens, then you might wish to replace this with the Canon RF 24-240mm F4-6.3 IS USM, which combines wide and telephoto into a single versatile lens, allowing you to simplify the kit you carry around with you, which is great if you're into travelling.

A man in a yellow waterproof coat taking a photo with a Canon EOS RP and Canon RF 24-240mm F4-6.3 IS USM lens.

Canon Ambassador Richard Walch exploring Norway with a Canon EOS RP and Canon RF 24-240mm F4-6.3 IS USM lens, which he found to be the ideal travel lens.

Which of my Canon lenses can I use on my full-frame camera?

The first letters of the lens name will tell you the type of lens it is. You will probably be able to keep and use many of your existing lenses when switching to a full-frame camera, but there are a few things to bear in mind.

EF-S lenses can be used with full-frame mirrorless EOS R System cameras with an EF-EOS R adapter. However, the resolution you get from your camera will be reduced, as the lens won't cover the full-frame sensor. I would therefore look to replace EF-S lenses with their RF equivalents if moving to the full-frame EOS R System. EF-S lenses will not work with Canon full-frame DSLRs, so if you prefer the feel of a DSLR camera and choose that path then you will have to replace them with EF lenses.

EF-M lenses are designed to be used with EOS M series cameras only, so if you change to full-frame you will need to buy EF or RF lenses to go with your new camera body.

EF lenses are compatible with all Canon full-frame cameras – with an EOS R System camera, you will need an EF-EOS R adapter, but there will be no loss of quality or functionality. EF lenses will also work almost exactly as they do on your current camera, the only difference being that your EF lenses will appear wider than on an APS-C camera, as the APS-C format introduces a 1.6x crop to the image. If you like to use a 50mm lens on an APS-C camera for portraits, then you might want to consider using an 85mm lens on a new full-frame camera in order to achieve the same framing.

A fairly small bird sitting on a branch with a fish in its beak.

Two images taken from the same position, using the same lens. This one, taken with the full-frame EOS-1D X (now succeeded by the Canon EOS-1D X Mark III), appears further away. Taken with a Canon EF 800mm f/5.6L IS USM lens at 800mm, 1/500 sec, f/5.6 and ISO800.

An image of a bird on a branch taken from the same position, seemingly slightly zoomed in.

This image appears closer because of the crop factor of the APS-C sensor in the camera used, the EOS 7D Mark II. Taken on a Canon EOS 7D Mark II with a Canon EF 800mm f/5.6L IS USM lens at 800mm, 1/500 sec, f/5.6 and ISO800.

Should I consider replacing my EF lenses?

EF lenses will work on all full-frame cameras, but moving to an EOS R System camera could be an opportunity to take a look at the range of new-generation RF lenses available. Taking just one example, there are clear benefits in switching from the Canon EF 85mm f/1.8 USM to its RF counterpart, the Canon RF 85mm F2 Macro IS STM.

First, the design of the RF mount means that optical elements can be positioned closer to the image sensor, producing higher quality images, particularly in the corners and when the lens is used at its widest apertures. Second, the RF lens allows closer focusing, which is especially useful when shooting portraiture and detail. Third, the RF lens features an Image Stabilizer, which will keep your shots steadier and, if you're shooting video, make your footage that much more watchable.

A black and white shot of a boxer throwing a punch.

Full-frame mirrorless vs. full-frame DSLR

One of the world's most experienced action photographers, Richard Walch, compares the features of the flagship EOS R5 and EOS-1D X Mark III cameras.

Are there any disadvantages with full-frame?

For sports and fast-moving action photography, the crop factor and shooting speeds offered by some APS-C cameras can be matched only by top-performing full-frame mirrorless cameras such as the Canon EOS R5 and EOS R6, paired with some of the recently introduced RF lenses, such as the Canon RF 600mm F11 IS STM or RF 100-500mm F4.5-7.1L IS USM.

A common question when considering full-frame is whether it's more expensive. Full-frame cameras and lenses used to be out of reach for many people, but models such as the EOS RP have made full-frame more affordable than ever before. If you have sports or action as one of your main interests, though, I would recommend one of the more advanced full-frame cameras in Canon's EOS R System range with higher speed and performance.

The final word

Moving to full-frame requires some reflection about the photography you're doing, your future aspirations and the camera and lenses that will best support you. The reason most people make the switch is to experience the benefits I've mentioned, and to expand what is possible thanks to the cameras and lenses available in the full-frame range. It could also provide you with an opportunity to have two cameras for different purposes, making use of the strengths of each at different times.

John Maurice

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