Key Camera Specifications Explained
There are many physical characteristics that are essential to the way in which a camera operates but most can be set aside except for a couple of them that have direct impact on image quality and usability. It is important to note that explanations are aimed at a beginner to intermediate level of knowledge pertaining to photography.
Image Sensors are the single most important component in the entire camera, no matter the type of equipment that incorporates them. These components evolve slowly over decades as various approaches improve the initial performance of a particular design. Changes over a decade are slower than release cycles of products that incorporate them. In order for manufacturers to promote their products as improved designs, they must rely on other aspects to achieve differentiation.
Cameras that incorporate sensors have their own requirements in terms of size, cost and power usage. This means that a design that works well in a large camera is ill suited for a small one. Phones in particular require the most compact image sensors that have low power requirements and are also affordable enough for a manufacturer. The size requirement is the most important reason for the compromises that that a phone has in terms of image quality. It is very hard to reach a good enough result.
Some configuration details may not be disclosed about product manufacturers since they consider them to be a commercial secret.
We may consider that a simple central focus in a scene you want to capture may be enough to reach a good quality output, but this is very far from the truth. A good camera has to determine the best focus by analyzing multiple areas in the same image for -over and -under exposure. Advanced image sensors may also be able to slightly bias the initial shot to create a more even image. While the discussion seems technical and sophistic, the above presentation is due to manufacturer secrecy and best-guesses about implementations.
Having on-demand focusing abilities works perfect with touchscreens for smartphones and newer generation professional cameras. Older professional and semiprofessional cameras only had a cumbersome way of focusing that failed if the subject was not placed precisely in the center of the frame or at a point where the camera could easily detect. Angled shots were particularly troublesome. More modern designs fare better in this respect.
Affordable professional cameras have a 9 point focusing ability while newer ones up to around 500 points focusing ability. Although numbers over 100 may seem excessive, the issue is that you may rarely have 100 of them used to determine where the focus may lay optimally. Having less than 10 points at a time is possible with complex scenes with a lot of transitions elsewhere than on relatively straightforward areas, as can be the case with rounded objects. You may never have too many potential focusing points and only a couple of them that may be readily used for focusing adjustments. Keep in mind that with professional cameras you may not have easy ways of setting where the focus may be, as in smartphones.
It is advisable to spot the most advanced focusing system and image processor in cameras. Even if you may not have a top-of-the-line model, you may still reach, on average, more consistent results.
A colour image sensor, as almost all cameras have and advertise, is a compromise in itself. Any filter through which light passes, and particularly small ones, are more prone to consistency issues and poorer image quality. As the image is split into the R(ed), G(reen) and B(lue) primaries, the image has less brightness and contrast. Most cameras actually have a pattern of light sensitive cells that may mean that more detectors are devised for luminance than colour information
Larger, professional cameras may have 3 separate sensors, each being used only to capture a particular color, such as red, green and blue. These products have the advantage of being marketed to a public that is willing to pay more for specific features. Such an ability actually offers at least three times the accuracy of images being captured, making sure that colors never bleed on adjacent areas and contrast is not compromised.
Professional cameras also offer more accurate HDR or high dynamic range capabilities, being clearly designed for 10-bit per colour output. Regardless of your immediate requirements, as these may still imply a standard 8-bit per colour, it is good to be able to use the camera for different tasks in the future or for experimentation. A clearly specified HDR accuracy may also imply better overall capturing capabilities and a better image processor.
Rarely more than a passing mention about the sensor features is present. Unless otherwise specified, almost all cameras have a single colour image sensor and the layout of light detectors is unknown.
Sensor Image Size Rating
The sensor image size in MP or mega pixels, million pixels in total, is a metric used to indicate the potential actual resolution of a generated image. A greater resolution usually translates into more detail that can be captured. Unfortunately, a greater resolution reduces the amount of useful light that falls on each cell that is part of the sensor, leading to a poorer end image. This is the reason why sensors have a set resolution and, on a specific decade, the performance is relatively limited, as developing a sensor with better sensitivity and greater resolution is no easy task.
It is essential to note that professional equipment specifications is accurate while consumer devices, such as smartphones, can have unrealistic claims of such performance fueled by marketing goals. However, even in this case, it is important to know that the sensor image size is less important than sensor's physical size, as the surface are exposed to light is the single most important factor in determining the potential capability of a camera. This surface needs to be as large as possible to capture light in a split second and there is no reliable way to compensate for a small sensor.
The advertised value of a phone camera's image sensor has steadily evolved into a marketing information that has, unfortunately, much less relevance than it had in the past. Before the advent of advanced image processing, this value was almost always the native capability of the image sensor inside a camera. As development of new sensors with higher density, able to capture higher resolution areas at the same size hit a technology limit around 10 years ago, manufacturers turned to image processing and algorithms to boost the perceived resolution, which has nothing to do with the actual capability of a sensor.
In actual terms, a phone sensor could present a 10-25MP value, while the advertised value can reach 100 or 200MP. Semi-professional and professional cameras have reliable sensor MP ratings and are more capable due to the image processors incorporated inside.
All cameras no matter their type, have a lens system that allows them to capture images. Smartphone cameras have mostly fixed lenses, while professional cameras have removable lenses, giving them the best flexibility but also making them highly expensive. Lenses can be characterized by focal length, aperture, distortion, astigmatism and many other physical properties. For most users, however, the focal length is the single most important factor. Note that the focal length is a way to measure the distance at which a lens focuses light towards an imaginary 35mm film or sensor.
While professional photographers discuss about their optics as commonly having 18mm to 55mm focal lengths, hobby photographers use 1x, 4x, 8x, or zoom factor properties. A lower focal length is required for closeup or portrait photos while a larger one is adequate for large, landscape scenes.
There is absolutely no substitute for having a large number of fixed lenses or a variable one that can cover most requirements. Even complex post-processing does not create the best results. You need to understand what focal length you need for any task, through experience. Lower values are for close-ups, larger one for long distance shots
Lenses, Focal Length, Magnification, Aperture
Introduction to the magnification factor
In general, it is better to avoid completely the zoom factor consideration and focus only the lens focal length being used for each camera's optical system or, in professional cameras, to compare between different optical systems. This is due to to the fact that the zoom factor only relates to the ratio between the initial focal length of a variable system and the maximum focal length it may reach. In general, it may be flexible to have a large magnification factor although higher ranges come with issues in focusing and comfortable, precise user setting.
For instance, a magnification or zoom factor of 5 can be for a lens set that goes between 10mm to 50mm, as well as the one between 50 and 250mm. However, the 10mm focal length has a totally different impact on the maximum adequate focusing distance than a 50mm one. The higher the lens focal length, the closer an object may look and the better your chances of focusing on it properly. However, large focal length come with the issue of less light that may enter the optical system and higher influence of even sight movement on the stability of the camera shooting.
Try to avoid the temptation of using the magnification or zoom factor for anything more than reference between similar optical systems in a product class, as between smartphones or cameras. You cannot compare the lens system capabilities of one with the other because the sensor and lenses used are different
The magnification or zoom factor
When operating in the default mode, all cameras have a 1X or no magnification factor. This allows a camera to take a picture that is close to what our eyes perceive. Our eyes also have a lens, although our lens is extremely flexible compared to our cameras. In order to take a wider picture than our eyes see, such as for a panorama, you need less than 1x zoom factor, while for closeup pictures, such as on subjects at events, pictured from a distance higher than 50 meters, you need at least 8x to 16x zoom factors to end up with usable pictures. This is why you need at least 4x zoom factor for decent amateur or hobby results, even on smartphone cameras.
Most consumer and semi-professional cameras will advertise the zoom factor in two ways: an optical one and a digital one. The optical zoom factor is the most important and the single definite argument to make a device more flexible. A good camera should be able to accommodate high zoom factors although this will also make it more expensive, as lens systems that are able to achieve such results are more complex to manufacture and configure. Digital zoom factor is created by applying various post-processing techniques, leading to slightly more blurred images, as you would create if your image would be stretched or zoomed in your image editor. There are various ways in which a camera signals transitioning from an optical to a digital zoom, and you need to avoid going over the known zooom factor limitations of your current lens.
It is advisable to observe that the higher your optical zoom factor or lens focal length is, the more your camera will be prone to suffer from the slightest movement or instability. When creating closeup pictures, it is good to have an extremely steady hand but it is much better to capture images using tripods and stands. Professional cameras have the advantage of high variety of lens systems that are tailored to any photo, from closeups to long distance or telephoto lenses. They can also be used on different cameras, which means if the camera has the same mounting system it can be easily used on your new one. For instance, these optical systems can have polarizers and lens hoods which improve capturing abilities in intense sunlight.
Get used to different lenses and zoom factors, but avoid ever using digital zoom or higher than optical zoom magnifications while taking pictures, to avoid reducing image clarity. Use tripods and stands to have steady shots at closeup captures.
Determining the zoom factor from focal length (professional cameras)
Having a good understanding of a professional camera is essential and covers the optical system. A professional camera may be sold as a base, without any optical lens system, with one optical kit or with two, depending on product and manufacturer's preference. Optical systems can also be purchased separately and replaced as needed, if they fit the same mounting systems. If they do not fit the same mounting systems, special adapters are required.
To calculate an equivalent zoom factor for an optical lens system when given the focal length, you take into account the minimal and maximal focal distance measured in mm. For instance, one lens system may go from 55mm to 210mm while another may go from 18mm to 45mm. The first one will have an optical zoom factor of 3.8X or 4, for most practical purposes, while the second one has only a 2.5X optical zoom factor.
Keep in mind that even if you determine the magnification factor it matters much more what focal length your camera has, as this will determine how well it can focus at a specific distance from your subject.
Knowing how much of your lens surface can be used to let the light pass towards your image sensor is known as the lense's aperture. It is usually indicated through a ratio, usually presented as F/(fractional value) or F(fractional value), where F is the focal length of the lens. The value is either fixed, as is on fixed lens systems that most smartphone cameras have, or variable, as in most lens systems for professional and semi-professional cameras. If two values are present, they are the minimum and maximum values that are available at each ends of the focal length domain. As expected, only cameras that have removable optical systems may have different focal lengths and different apertures, depending on what the manufacturer offers.
Typical apertures are F/2 to F/2.5 for smartphone cameras and F/4 to F/6 for professional cameras. However, as smartphone cameras have focal lengths around 20mm, while professional cameras have 15 to 55mm, it means that a professional camera can typically work much more reliably in different light conditions, as they can adjust to overly bright or dark scenes more easily.
A lense aperture also influences the way in which a subject is focused, as smaller apertures translate in better closeup focusing while larger ones are used to show specific details on a larger subject or for distant shootings. In this context, large apertures are low ratios such as F/2 while small ones are F/16. The small or large designation pertains to how wide the opening for the light is, with F/16 being a very narrow opening and F/2 signalling the widest opening.
In general you note what specific apertures translate to in your pictures, and note where the best focusing occurs, at a given similar distance. On professional cameras, you evaluate results results similarly, taking into account what influence changing the lens system or focal length has on your subject.
Effective Sensor Surface Area
All sensors operate by capturing photons on a small surface area which is usually expressed in micrometers. The larger the surface, the larger the amount of light that can be quickly captured but also the more space is required and the sensor itself is more costly to manufacture. This is main reason smartphones have very small sensors with surfaces around 1/1.3 0.6 square inches or around half a square inch, while a full frame sensor for a professional camera is almost two times as large, 1.34 square inches or 864 square mm.
Sensor size can never be compensated through image processing but results are acceptable even with smaller ones. The most obvious limitations are in the context of low light or massive variations in brightness around the scene. Over-exposure and under exposure may be the most obvious manifestation of this limitation.
A good smartphone image sensor mush have at least a 1/1.3 square inches or 0.76 square inches surface area. Sometimes the value is expressed as F divided by another value, where F is the full frame sensor surface area. A good professional camera must have a full frame sensor surface area of around 1.34 square inches.
Integrated display size and type
The most common display type is an LCD and most professional and semi-professional cameras have such displays. In many ways, and LCD offers the poorest image quality display technology. A chassis display or an internal one is used only as reference and not to determine the picture quality which explains the discrepancy in terms of camera abilities and details provided by the LCD screen. Most displays are of low resolution and do not have touch abilities, particularly on professional models.
A viewfinder is better than a typical display as it can ensure perfect subject focusing and framing abilities. Without a viewfinder, as in the case of smartphones, a large, high quality display is mandatory. OLED and MicroLED screens have the best contrast, colour and thus image reproduction capabilities. Keep in mind that, however, the saturation profile used out of the box is wrongly set on "vivid", to entice costumers. A good and large screen helps to quickly determine if the capture was good or not, without resorting to very large displays. Such displays also helps to better get accustomed to camera limitations and use it to the best extent.
Larger displays are highly recommended. A viewfinder is highly important in professional and semi-professional cameras. A good smartphone used for photos should never have an LCD screen but an OLED type for best image reproduction!. Camera viewfinders are best when freely-orient-able, to account for various scenes.
Image output formats and video recording abilities
All cameras save images in JPEG or JPG format for portability reasons, as it can be processed and displayed properly in any device, whether we consider mobile phones, tablets, television sets, and in any software application. This versatility is highly important even if the image quality available from the camera may be better than what the JPEG format offers.
More advanced cameras and devices catering to professionals may list RAW formats as well, since it is a less processed image format that can extract more quality out of the initial shots. For most intents and purposes, RAW image editing and processing is much more difficult and the RAW format is specific to each camera, requiring dedicated support in image editing applications as other abilities to display such images is not available. Note that any processed RAW image will probably end in JPEG format anyway, as it is used on the internet or in other situations. However, having a good initial format or using it in subsequent edits makes PNGs and other loss-less formats the preferred choice that also offers versatility. Few cameras support PNG format savings, although some smartphone apps can be able to save in the PNG format.
Video recording capabilities expose other important details about the camera sensor. Processing video on the fly is very difficult so the camera sensor image capabilities are much more readily exposed here. A camera that advertises a very high picture resolution in MP or megapixels, but a very poor ability to record video than another similar one, hints at unrealistic still image capturing claims. A good camera should be able to record also videos at a 4k resolution with at least a 60Hz or FPS (frames per second) ability. Higher resolutions and frame-rates are an indication of good sensors and logic but resolutions as high as 8k are somewhat impractical for video footage production and editing at the moment due to massive processing and storage requirements.
Any mention about RAW format output signals products catering to professional users. High video resolution at high frame-rate video capturing abilities, such as 8k at 60fps, is an indication of a very good sensor capability. In most circumstances, a 4k filming at 60Hz or FPS should be available to the camera, at the minimum.
Battery capacity rating in mAh
The initial battery capacity of a mobile device is essential for portability. The value reflects the maximum current than can be delivered by the battery for an hour, before it is depleted. Note that the current requirements of the device itself that uses the battery is not presented so battery capacity evaluation is essentially empiric. A battery has the best performance when new but slowly degrades in hidden ways as it ages. After a couple of years of intensive use, a rechargeable battery becomes non-functional and has to be replaced.
The amount of energy required by the camera in different operating modes and on different products from the same manufacturer or others can be used as reference and nothing else. A larger battery capacity rating on a product class generally suggests a better performance as high power rating batteries are more expensive to manufacture. In general, a device is designed around a specific battery capacity so most products behave relatively similar in a product range from different manufacturers. Having a very large capacity battery or a high energy efficient device is costly to design and manufacture.
Using the camera on video recording mode or frequent image captures with the screen set to high brightness can quickly drain a battery. This is even more important for devices that can be used in multiple ways, as in the case of a smartphone. Unless the smartphone is permanently powered when in video recording mode, the brightness should be reduced. Most applications cannot record with a closed screen which means that a long video recording will deplete the battery much faster.
Larger batteries help autonomy on products in the same range. Capacity alone cannot be a criteria to select or avoid a product but the battery technology being used and the available autonomy expressed in hours can hint at good designs, particularly for smartphones.
Networking and Data Storage Ability
Using memory cards for transferring images and videos is the most readily path towards editing and content creation. Most semi-professional and professional cameras can be connected to a computer to transfer data or do so by taking out the internal memory card and placing it in a card reader. Physical memory card access is the fastest way of transferring, particularly in the case of videos. Wireless transfer may be available in certain camera models but it is not a feature likely to operate as seamless as direct memory card file transfer. Wireless networking capabilities depend on more circumstances and cameras may not be particularly designed with this feature in mind. Transfer speed and performance may not be similar to wired connections although it may be sufficient for occasional use.
Some of the newest smartphones do not have memory or SD card storage connection or slot capabilities. In these circumstances it is essential to consider the performance of wireless transfer abilities and the need to set up a system centered around access to shared folders and installation of an application that is suitable for wireless transfers to a computer. Many applications can be installed free of charge on an Android or iPhone product which means that such tasks can be reliably and quickly solved. Major requirements for smartphones come down to having at least 256GB of storage space and Wifi 6 networking capabilities.
Professional cameras have different storage requirements. Photos are the least demanding, size and speed-wise, a 128 or 256GB should be plenty even for intense photo-shoot sessions of around a week, while not enough for extensive video shooting in Full HD or 4k at 60fps for even a single day. For these circumstances, it is best to have at least a 512GB to 1TB memory card and 512GB cards are particularly affordable nowadays. Speed ratings matter less when recording except when below class U2, although they do matter when transferring multiple files, as is the case for photos. You can reliably use MicrosSD instead of SD cards, with adapters, to transfer data faster between devices with card readers. Capacities of 2TB are the maximum for the current SDXC card standard and higher ones will use a different standard. Keep such information in mind 5 years down the line, for reference.
When wireless data transfer is required, particularly for smartphones without microSD card slots, at least 256GB storage and Wifi 6 abilities are required. Professional cameras require 512GB SD card sizes for optimum storage when capturing film, for 30000 photos, you can get away with less than a quarter of this size.