Nikon has just unveiled its first full-format sensor hybrid, it's time for explanation. What is it really and what is the interest of this sensor for the photographer? More details below.
Before the world of photography almost exclusively became digital, the sensors did not exist. The information was collected by film, 135 (full-format, ie 24 × 36) or 220 (medium-format), to name just the two most used ones. The manufacturers have therefore adjusted the devices to the format they wanted. But with the emergence of digital, sensors of different sizes and resolution have appeared in the devices.
What are the different sizes of photosensors?
Depending on the device types and ranges, there are many sensor formats. And even between the different subcategories (CCD, CMOS) there are variations in their actual size. The one who mainly interests us here, and who is for professional boxes, is full-format or full-size, whose dimensions are 24 x 36 mm. This sensor format can be found in products such as the Nikon D850, the Canon EOS 1DX on the SLR, or the Sony Alpha 7 and Alpha 9 hybrid side. Nippon is currently the only one that produces full-frame hybrids for the moment, and its devices allow it to be the first full-format supplier (hybrids and SLRs) combined in the US in 2018.
The APS-C sensor is the sensor that is most often cited when one invokes small differences in size and the famous one harvest factor from Nikon (1.5x) and Canon (1.6x). Nikon's APS-C, for example, is 23.5 x 15.6 mm (D500, D7500 …) while Canon is about 22.5 x 15 mm (6D II, 77D …). To explain, the harvest factor or multiplier is the frame of the image (here APS-C) compared to the reference format, full format. We will come back to this a bit more.
There is also APS-C on Fujifilm, with the recent X-H1. Very popular too, the 4: 3 microformate (17.3 x 13 mm) is mainly used by Panasonic on its G9 or GH5, but also by Olympus with its E-M1, E-M5, E-M10 or some PEN .
Finally, smaller sensors are present on compact devices – and smartphones – where the search for compactness has made their attendance possible. There are different sensor sizes: 1 inch, 1 / 1.7 inch, 1/2 inch, 1 / 2.3 inch or 1 / 2.5 inch.
The advantages of a full-size sensor
Nowadays we find ourselves at an age when manufacturers can integrate a large number of professional components into smaller housings than standard SLRs & # 39; s. Sony full-format hybrids launched the transition in 2013 with the release of the Alpha 7, removing the mirror and choosing a beautiful OLED electronic viewfinder. The mechanical stabilization came with the generations, up to the Alpha 9, which immediately positioned itself as a serious competitor professional SLR cameras from the two giants that Canon and Nikon are.
Immediately taken from film and film format 135 (35 mm), full format has become the norm. It is therefore easier to navigate without going through the conversions imposed by other formats. Let's explain it: with the same focal length, a smaller sensor than ours full-size covers a narrower field and gives the impression of resetting the image, while the full size more or less corresponds to the field of view of the human eye. A 50 mm lens on a full-size sensor is thus a 50 mm, while a 50 mm lens on an APS-C is a 75 mm equivalent 24 × 36. This ratio between focal lengths of 50 mm and 75 mm on APS-C sensor housings corresponds to what is called the multiplication coefficient. For APS-C sensors from, for example, Nikon or Sony, this is 1.5x, as mentioned above. Directly coupled to the previous point, the full format makes it possible to obtain lenses with a wider angle and to avoid the optical defects associated therewith.
But the other advantages that are directly related to the size of this sensor are those that mainly appeal to professionals. Large sensors can capture more light with larger photo sites. Indeed, if we use sensors of different sizes, but identical resolutions, for example 20 megapixels, the photo's of the largest sensor will be larger. This reduces the exposure time for the same amount of light received, which also promotes sharper image and convenience in circumstances where light is scarce. Some manufacturers also take the opportunity to offer high resolutions (for example, 45 megapixels) for an amount of photos that remain essentially the same as a PSA-C.
Full-size also promotes the increase in sensitivity. Indeed, if photo's capture more photons, they can somehow afford to generate more noise before it becomes visible or annoying.
Is full format suitable for all applications?
If wide-format images are preferred, small sensors prefer long focal lengths that may interest wildlife or sports photographers. The multiplier here is in favor of APS-C and other smaller sensors.
Full-format telephoto lenses are therefore more difficult to obtain, and with a focal length and an equivalent aperture a full-screen lens is much more expensive than the other. The systems are also much heavier and more cumbersome. In this, the full-format hybrid is an ideal compromise and it is easy to understand why professionals and brands are interested more and more.
A final disadvantage – or advantage, according to – due to the full size, is that it offers a smaller depth of field than other sensors with a focal length and an equivalent diaphragm. Street photographers may prefer smaller sensors, so that, apart from making the photos more discreet, they can sharpen a larger part of the image.