Full frame or APS-C? What to choose?

Faced with the inexorable tide of smartphones which gradually tend to replace cameras, manufacturers react by focusing on models with larger sensors, which yield more and whose image quality seems beyond what can be produced. a smartphone. They repatriate their activity to a fortress, sheltered from these competitors. Even Panasonic, used to Micro 4/3 sensors, launched full frame models recently.
And they are also abandoning DSLRs whose sales have fallen by 10% each year since 2012 (and even 30% in 2019) in favor of mirrorless cameras.
But will this be enough? Samsung announced in May 2019 a 64 megapixels sensor with dynamic interval and ISO higher than those of an FF (Full Frame)!

While offering better margins to manufacturers, full frame or 24x36mm cameras are nowhere near as common as 15x24mm APS-C sensor cameras. (See table in the appendix). Are they really better?
Should we follow the trend towards what manufacturers want to take us, whose goal is above all to maximize their profits, or can we instead turn to an APS-C and obtain images of enough good quality?

Bigger sensor gets more light

Because of its larger surface, and at equal resolution, the photocytes are larger on an FF. This allows for sharper images in low light with less noise.
But the larger format reduces the depth of field and to keep the subject fully in focus, you have to reduce the aperture, which reduces the light as much!

The amount of light also depends as much on the lens and its maximum aperture as on the sensor. A 1.7 aperture lens on an APS-C captures more light than a 3.5 aperture lens on a full frame. These large apertures are obtained especially on fixed focal length lenses.
Obviously you can also have a larger aperture lens on the FF, but other drawbacks appear, such as size, weight and a big cost.

A smaller sensor allows better stabilization in the body

It is a fact that Micro 4/3 cameras are the best stabilized cameras and that the APS-C also have better stabilization in the body. Moving the sensor to compensate for camera shake is easier when it is smaller.

IBIS (In Body Image Stabilization) is very useful in video, and with unstabilized lenses. It also makes it possible to increase the exposure time and therefore to obtain more light with a smaller sensor, at same aperture.

Canon 55-250 (80-400 with crop factor) vs Tokina 80-400

The size (and price) of the lenses are in proportion to that of the sensor

The laws of physics mean that the larger the sensor, the larger the lens must also be, for the same focal length. And the laws of economics make it that much more expensive.
This is why the Nikon P1000 with its 1 / 2.3 "sensor can reach a focal length of 3000mm and costs less than 900 €, while Canon's lenses for full frame of 600mm may exceed 10,000 €. The Nikon 800mm f / 5.6 costs 16,000 €.
Note that the APS-C crop factor offers you the equivalent of 50% or 60% more focal length for free, with no loss in image quality.

A lens that has a larger aperture is usually also larger. So we see the advantage of a smaller sensor: obtaining a larger zoom and a larger aperture at the same size and price.

Reducing the depth of field makes it harder to focus

All other parameters being equal, the larger a sensor, the more the depth of field is reduced, in other words the background is more blurry when focusing on a subject. This is either an advantage when you prefer to highlight the subject, and have a blurry background, or a disadvantage for overall shots (and travel).
You must know that:

The smaller the depth of field, the harder it is to get focus. So with settings on the aperture and focal length, we can improve the focus, but the APS-C sensor will always have an advantage.

The resolution is not often better

In theory, a larger sensor allows for greater resolution. In practice we see that this is not the case, perhaps because managing a higher resolution would require a more powerful processor, while manufacturers use the same model of processor, the latest, on all new cameras, including bridges and compacts. Another reason is the battery life which decreases as the images to be processed and displayed are larger.
This is why the Sony A7 IV, the best-selling full frame at the moment, has the same 24 MP resolution than the APS-C A6400.
The Canon M6 II has a resolution of 32 MP with an APS-C sensor and the Fujifilm X-T5 40 MP. While the recent Canon R6 II and R8 with full-frame sensor have a resolution of only 24 MP like most FF cameras. Only high-end FF cameras have a higher resolution.

Image quality

It largely depends on that of the lenses, but a larger sensor allows for better resolution, so more detail is reproduced. For the same generation of sensors. Manufacturers sometimes recycle old sensors into new devices. This is the case of the Canon RP, the Nikon Z5. These devices perform better than modern APS-Cs in low light but don't reproduce more detail otherwise.

Opinion of a photographer

“If I needed to buy a camera tomorrow, I would buy an APS-C model. Full frame can do more (reduced depth of field, better tonal quality, better low light performance), but these improvements come at the expense of size, and, uh, cost. That's more than you need. I also claim that there are a few APS-C models that offer a better balance between taking pictures and videos."

Source: Richard Butler.

Recap: The benefits of APS-C

  1. Lenses size: they are reduced in proportion to that of the sensor.
  2. If you intend to use telephotos, APS-C is always preferable. Full-frame is better for wide angles.
  3. Video: It is easier to improve the picture quality without overheating the device.
  4. Price: APS-C is always less expensive for equal performance.
  5. Stabilization in the body easier with a smaller sensor. Mais that is not the case with the most recent cameras.
  6. The depth of field is greater all other factors being equal, so the images are sharper, especially the background.

The full frame format have an advantage for motion in low light, and often a larger dynamic range and more details.


Full frame allows for better images, especially in low light, but at a cost. You also need a good lens and the whole thing will always be heavier and more imposing. To the point of encouraging you to leave the camera at home and take your photos with your smartphone. Which makes the comparison useless.

Examples of costs

Comparison between APS-C and full-frame cameras:

  • Sony A6400 + Sony 18-135mm (equivalent champ de vision plein-format 28-200mm): 1300€.
  • Sony A6400 + Tamron 17-70mm F2.8 (equivalent 25.5-105mm): 1500 €.
  • Fujifilm X-S20 + 18-55mm: 1800€.
  • Canon M50 II + EF-M 15-45mm + EF-M 11-22mm f/4-5.6 IS STM (400€) + Adapter + Canon EF-S 55-250mm IS STM (150€) : 1300€.
  • Canon EOS R8 + RF 24-105mm F4-7.1 IS STM: 2200€.
  • Nikon Z5 + 24-200mm: 2000€.
  • Panasonic S5 II + 20-60mm: 2500€.

See also ...

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