Image sensor types and sizes
Image sensor types and sizes
Usual Digital sensor formats
|Format name||Horizontal dimension||Vertical dimension||Sensor area in mm2||Crop factor||Manufacturers|
|Middle format||40-54mm||30-40mm||1452||0.64-0.8||Mamiya, Phase one, Hasselblad, Pentax, Leica|
|Full frame||36mm||24mm||864||1||Canon, Nikon, Sony, Leica|
|Super 35mm film||24.9 mm||18.7 mm||466||1.39||Canon Cinema EOS|
|Aps-C||22.3-23.6 mm||14.9-15.6mm||332-368||1.5-1.6||Canon, Nikon, Sony, Pentax, Fujifilm, Samsung, Leica|
|Canon Powershot G1 X Mk II||18.7mm||14mm||262||2||Canon|
|Micro 4/3, 4/3||17.3mm||13mm||225||2||Olympus, Panasonic|
|Nikon Cx mount||13.2mm||8.8mm||116||2.7||Nikon 1 cameras has this sensor size|
|1″ Format||13.2mm||8.8mm||116||2.7||Sony RX100, Sony RX10, Samsung NX Mini, same as Nikon 1|
|2/3″ Format||8.8mm||6.6mm||58||3.93||Fujifilm X-S1, Nokia 1020|
|1/1.8″ Format||7.18mm||5.32mm||38||4.74||Panasonic Fz 50, best Point and shoot cameras|
|Compact cameras||5-7mm||3-6mm||15-40||4-6||Canon, Nikon, Panasonic, Sony, Fuji, Pentax, Olympus, Samsung, Kodak and many others|
One important note here is the sensor area which refers to how much light the sensor can capture. For example the linear difference between the Aps-C and Full frame cameras are 1.5-1.6x but the difference in area is more than double, which refers how much light comes in. The difference between Full frame and 4/3 is 864/225=3.84 means the Full frame camera almost captures 4 times quantity of light than the 4/3 system camera. This can explain the difference in low light performance between these cameras. More light less noise as we can see in our images.
Image sensor manufacturers
There are huge number of image sensor manufacturers out there. For digital cameras and smartphones the biggest manufacturers are Sony, Canon, Samsung, Toshiba, Nikon, Panasonic.
Sony makes sensors for Nikon and Pentax cameras as well. Sony has approximately 40% market share (2015), Samsung (15-20%), Canon (under 10%) and others has much less.
Sony supply sensors for Apple Iphones and there are Sony sensors even in some Samsung high-end smartphones as well, although Samsung is a huge sensor supplier as well. Other big suppliers are Omnivision, Aptina, STmicroelectronics and Galaxy core to name a few but there are many others.
The image sensor is the most important part of the digital camera. Basically the image sensor has the biggest influence on final picture quality (we don’t talk about lenses, just cameras see below). The sensors price is the main factor in the camera price. The majority of the cost of the high quality digital camera is the cost of the sensor. There is an incredible competition between manufacturers based on sensor technology. Generally the bigger sensor means or equals better quality images. But this is not so simple, some smaller sensors are very good and can compete with bigger sensors. Today (2014) the small 1/2.3″ or 1/2.5″ sensors of the compact cameras not really compete with bigger sized cameras. The depth of field is also shallower at cameras with bigger sensor size, which is preferred for portraits to beautifully blur the background.
No matter how good your sensor is if there is a middle or low quality lens sitting in front of it. Generally speaking the lens is much more important regarding picture quality than the camera. What can a not appropriate lens can do with the camera’s images ? Lot of bad things actually. First not proper colors, and we already miss lots of information, weak contrast, and lack of sharpness means the details has been lost never come back in any amount of sharpening. I we compare bad lens+good camera or good lens+bad camera in Dslr world usually the second combination win hands down, unless we manage to find a really bad camera.
Crop factor shows the sensor size, compare to the film or Full frame (36*24mm) sensor size. We use diagonal dimensions for calculation. If the sensor is bigger than Full frame than the crop factor is smaller than 1. If the sensor is smaller than Full frame the crop factor is bigger than 1. Aps-C format crop factor is 1.6 or 1.5 depending on the sensor size of usually 22-23.6mm. Canon cameras has a crop factor of 1.6, other suppliers are usually 1.5 (Nikon, Sony, Fuji). The Middle Pentax 645D format crop factor is 0.78 for a sensor size of 44*33mm. Crop factor can be calculated if we divide the actual sensor(diagonal) size by 36mm Full frame camera (diagonal). For example Canon 30d 22.5mm sensor crop factor is 22.5mm/36mm=1.6. This factor also means that the same lens on a smaller sensored cameras has a focal length of the multiplied focal length. Let’s have an example: On Full frame cameras 50mm focal length is a normal focal length(as we see with our portion). On Aps-C sized sensor Canon 30d (crop factor 1.6) it becomes 50*1.6mm which is not normal lens, but a short telephoto. The smaller lens obviously only uses the center part of the lens. What if we put the same lens on the Middle format camera: on theory it will be wider, but usually the Full frame lens doesn’t designed for the middle format cameras this way doesn’t cover with light the bigger sensor. The border parts of the image(regions out of the 36mm sensor size) will be dark or darker.
Sensor format in “
The sensor format in ” can be misleading because it is not shows the real size of the sensor but refers to a lens size. For example 1″ format is not 2.54 cm as expected, but only 13.2 x 8.8 mm.
Medium format is bigger than 36*24mm Full frame format, usually 44mm or bigger
Hasselblad, Mamiya, Phase one, Pentax, Leica makes medium format cameras, seems perhaps Canon also interested to take part in this market segment. Interestingly nowadays almost all sensors are manufactured for this format by Sony.
Full frame or Film format
Canon Nikon and Sony and Leica has full frame cameras in April 2014. Perhaps this format is the most popular among professionals. Canon 1D X, Canon 1D C, Canon 5D S, Canon 5d Mk I, II, and III, Nikon D810, Nikon d800E, Nikon d800, Nikon d610, Nikon d4 s and many other Nikon cameras belongs to this format. Pentax has a middle format camera, but no Full frame yet.
The Full frame format sensor size is usually 36*24mm or a little smaller. For example 35.9 x 24mm.
Former Canon 1 series cameras has a sensor size of 28.7*19mm, with a crop factor of 1.3x. These cameras are discontinued.
Aps-C or Dx format
Perhaps the most used format today. Canon Nikon Sony Pentax Fuji Sigma Leica Samsung has Aps-C sensored cameras. Nikon also calls this Dx format.
The sensor size for Aps-C cameras are usually 22.5*15mm or little smaller, like 22.3*14.9mm. The crop factor is 1.5(Nikon) or 1.6(Canon).
Micro Four thirds format
Panasonic and Olympus makes Micro Four thirds system mirrorless cameras. The sensor size for Micro Four Thirds is 18*13.5mm. The crop factor is 2x compare to Full frame, the difference compare to Aps-C is 25%. The Aps-C camera is wider with 25% or the Micro 4/3 has 25% more reach compare to Aps-C cameras.
The 1″ format is relatively new Canon G1 X II has this format camera, and Samsung also has a camera with this size sensor. The sensor size is 18.7*14mm similar as the Micro 4/3.
Nikon 1 CX format
Nikon 1 cameras has CX format the crop factor is 2.7. The sensor size is 13.2*8.8mm.
Compact camera formats
The usual sensor sizes for compact cameras are: 1/2.3″ or 1/3.5″
Camera phones like Nokia iPhone sensor sizes
Some camera phones has relatively bigger sized sensors. The iPhone 5 has a sensor size of 4.54*3.42mm, the crop factor is 7.61.
Digital Image sensor types
The two sensor types are the CMOS and CCD sensors for digital cameras. Today almost everybody uses CMOS sensors, because of their better low light ability.
How to evaluate image sensors ?
There are 5 important parameters to check out:
1. Low light availability – ISO This shows how clean images the camera can produce in lower light environment without blurring the image. Higher ISO speeds also used to freeze action in sports or in wildlife photography.
2. Dynamic range – Dynamic range shows how the sensor handle bright and dark scenes on the same picture. The Dynamic range is measured in EV. Today best digital sensor has a maximum 14-15 EV dynamic range. New organic sensors (see below) reported to have 19 EV dynamic range.
3. Colour depth – How many colors the image sensor can capture
4. Resolution – How many detail can be captured by the sensor, how sharp images the sensor capable of making
5.Contrast – Contrast makes pictures “punchy”, without contrast the pictures are looks flat.
Most of this qualities are depend on the lenses as well not just on the sensor. Obviously sensor doesn’t catch something what is not there. A poor lens simply ruins the picture.
Low light availability or high ISO performance
Perhaps this is the biggest difference between small sensored compact cameras and interchangeable lenses Dsrl and mirrorless cameras. Most compact cameras makes good quality pictures up to iso200 or 400. After for higher sensitivities the picture gets grainy and all kinds of red dots and other artifacts appear in the image. On the Other hand some Dslr cameras can have usable ISO of 102,400. Most Aps-C sensored cameras has better image quality at ISO 1600, than compact cameras at ISO 400. What is it good for? To makes pictures in lower light situations and freeze action with high shutter speeds.
Cameras not like human vision. Dark parts of the picture gets simply black without details, bright part will be “blown out” whites also with no details. We can choose either we make a lighter image with more detail in the lighter parts of the image, or we darken the picture and has more detail in the shadows but the bright parts will be blown out, but cannot have both. Dynamic range refers to the camera ability how much extent can a camera can retain details both in the dark and light areas. Cameras with high dynamic range is much more usable, because in summer usually dark and very bright is usually presented on the same picture if we make landscapes. But even for wildlife or macro the dynamic range is very important and determine our ability to make nice images.
Colour depth is refer to how many colors the camera can identify. Today most cameras can identify huge number of colours. The difference is not so huge like at low light ability or dynamic range for example.
Resolution is a very interesting one. Resolution shows how many detail the camera can capture. But don’t be fooled by megapixels. I had a 8Mp Canon and 16Mp Nikon dslr camera. The difference in detail is not so much as you would expect, and even the sharpest lenses needed to see at all. If you have a sharpest very expensive telephoto prime lens like the Nikon 300 f/4 af-s, perhaps make sense to have the latest 24Mpix Nikon d7100, but for cheaper kit or consumer grade lenses perhaps won’t see too much difference, if any. Better to buy a better lens instead to pay twice the money for 5% difference. My 1680*1050 pixel monitor is approximately 2 Megapixel. If you want to print A/3 or bigger sizes perhaps makes sense of the bigger megapixel cameras, but other case not so much. Unfortunately today most cameras has this high megapixel rate, which is not the best for several reasons. If you check real pro cameras these cameras has not so many pixels usually.
Image sensor market today (2014)
Seems Sony makes lots of sensors for Pentax, Sony, for Medium format cameras and previously for Nikon as well (Nikon d7000 has Sony sensor for example). Canon makes his own sensors. Toshiba now makes the sensors for Nikon. Olympus, Fuji and Samsung also makes sensors. Today more and more imaging sensors are made without AA (anti-aliasing) filter. Nikon started this with a Nikon d800E and Nikon d7100, and there are other cameras also available without AA filter. The AA filter is used to eliminate patterns used because of the sensor made of pixels. On theory the picture is sharper without this filter. The difference in reality is not huge. Fuji makes an interesting new sensor, they uses different pattern that the commonly used Bayer interpolation in almost all other cameras which also allows to omit the AA filter, and results better quality images.
New organic image sensors
There are lots of information circulating in the internet about the new upcoming organic type image sensors. This sensors unlike the common silicon based sensors using organic membrane film instead of the commonly used photocells. These sensors are in quite an early stage of development as I understand. The informations are talk about extremely wide dynamic range, small size, very low noise, and high resolution in high iso speeds. If this is true can change photographic world in a huge level. Today’s sensors are far from real vision especially in dynamic range.