How to choose a digital camera
How to choose a digital camera, for the maximum yield of our photographic hobby.
Before choosing one of the different types of digital cameras, it must be perfectly clear what are your needs and aspirations: if the camera is used to capture the highlights of a trip or happy evenings with friends, the best choice will be without doubt a Compact or a Bridge, while if you see the camera as a means of artistic expression will be necessary, sooner or later, the purchase of a more challenging tool, such as a Reflex or a Mirrorless. In any case, it will not be enough to buy a more advanced camera to magically improve the quality of your shots: making effective photographs presupposes the study of photographic technique, a certain experience and a good dose of artistic sensitivity.
How to choose a digital camera | The Ultimate Guide
Understanding which type of camera best suits your needs is only the first step; for each of them, there are in fact on the market dozens of different models with different characteristics, and the choice of the most suitable one may not be so immediate; we therefore analyze the main technical features to be considered before buying a digital camera, be it compact, Reflex, Bridge or Mirrorless.
Usually, the resolution of a camera is interpreted as that characteristic that alone can indicate the quality of the product itself: “the more Megapixels the better the camera will be”; nothing more wrong. The Megapixel number, in itself, simply indicates the dimensions of the digital image, but not its quality level, indeed: by shooting with cheap cameras, the bigger the image, the more its defects will be evident. The digital cameras on the market today, especially the compact ones, sometimes boast disproportionate resolution compared to the modest sensor they mount, but normally it is simply useless to shoot at more than 10 – 12 MP with a low-end camera, as there would be no gain in terms of details.
Image quality and sensor dimensions
No data, on the technical sheet of a digital camera, can measure the image quality of his shots, but a fairly precise indication can be deduced from the physical dimensions of his sensor (not to be confused with the resolution).
The sensor of a camera is the equivalent of the ‘old’ film: it is the component that captures the light signals by translating them into digital information, and as a rule, the greater the image quality will be. The cameras currently in production are equipped with sensors of different sizes, but only the professional Reflex (and some Mirrorless) are equipped with a “Full Frame” sensor, the standard measuring 24 x 36 mm (the same dimensions of the most used negatives at the time of photographic film).
In addition to the sensor size of a particular camera in absolute terms, it is interesting to know the relationship between these and the Full Frame standard, a feature that takes the name of “Crop Factor”; to clarify, let’s take a few examples taking into consideration the sensor of some very popular camera models today. Canon DSLRs, like the Canon EOS 700D, have a sensor with a size of 22.2 x 14.8 mm, whose ratio with a Full Frame sensor (Crop Factor) is therefore equal to 1.6 x (this is the APS standard) -C).
An advanced compact, such as the Canon Powershot G9, instead mounts an even smaller sensor, the size of 13.2 x 8.8 mm that determine a 2.7x Crop Factor. The most economical compacts, such as the Nikon Coolpix L31, are equipped with a tiny 6.17 x 4.55 mm sensor that corresponds to a 5.7 x Crop Factor; to a sensor of this size, one can not ask for an excellent image quality.
Key feature of any lens, and therefore of any camera with a fixed lens, is the focal length, expressed in millimeters: it depends on the ability of the camera is to shoot the most distant subjects and to enclose in a shot even the largest scenes . To give an idea, let’s say that the angle of vision of a human being is equivalent, at a focal length of 40 – 45 mm and therefore, by shooting at this focal length, the same portion of the scene that can be perceived with the naked eye , reason why the lenses whose focal length is around these values are called ‘Normal’.
Shorter focal lengths, less than 35 mm, are called wide-angle, and allow to frame a larger portion of the scene than the human eye can perceive; a camera with a very small minimum focal length, such as 22 mm, will come in handy when you find yourself, for example, immortalizing a vast landscape, perhaps including elements in the foreground, or when you want to create a nice group ‘selfie’. On the contrary, focal lengths higher than 70 mm (many models exceed 300 mm in any case) correspond to the telephoto lenses, which limit the angle of view taken up, consequently allowing to capture subjects even at a considerable distance. Among the features of compact cameras and bridges, more than the focal range is often emphasized the power of the zoom, such as 10 x, 20 x or 35 x: this figure simply indicates the ratio between the minimum and maximum focal, but to know these values in absolute terms is certainly just as useful.
Moreover, under the ‘focal’ voice, in the technical sheet of many compact cameras and Bridge, you will often find values much lower than those we have brought as an example; this is due to the fact that the actual focal length (or better, ‘equivalent’) of a lens is closely linked to the size of the sensor to which it will be associated, and to the resulting Crop Factor we have already discussed.
We first mentioned the Nikon Coolpix L31, whose 6.17 x 4.55 mm sensor determines a Crop Factor of 5.7 x; the focal length of this camera, also reported on the body itself (near the lens) is 4.6 – 23.0 mm, but to know the equivalent focal, which is the really important data, we must multiply these values for the Crop Factor, obtaining in this case a focal length of about 26 – 131 mm: the lens of this compact camera goes therefore from a not very wide angle lens (26 mm) to a moderate telephoto lens (131 mm).
In compact cameras, however, the equivalent focal length is usually indicated among the technical features of the camera (though rarely highlighted), and it will therefore not be necessary to perform these calculations; however, the subject changes when it comes to interchangeable lens cameras (Reflex and Mirrorless); in this case, in fact, the same lens will determine a different focal equivalent depending on the camera on which it is mounted: a hypothetical 200 mm telephoto lens, will actually have this focal length only on a Full Frame camera, while mounted for example on a camera with APS-C and Crop Factor sensor equal to 1.6 x (like the amateur Canon SLRs), will behave like a 320 mm, with a much higher capacity.
One of the main technical features of a digital camera is the maximum sensitivity of the film or, more correctly, ‘ISO sensitivity’. Without going into technicalities, let’s say that the higher this value, the shorter the exposure time is necessary to capture an image, and consequently the greater the chances of obtaining sharp shots in low light conditions.
However, as the ISO sensitivity increases, the image quality decreases irremediably, and usually, using the maximum ISO sensitivity offered by the camera, for example 6400 ISO, the image will simply be unusable due to too much digital noise, while it will instead it is possible to obtain satisfactory shots up to a lower sensitivity, such as ISO 1600. This threshold, which the most expert photographers call (with a touch of irony) ‘maximum usable sensitivity’, is obviously subjective, and is not indicated in any technical data sheet; before buying a camera, the advice is to get on the internet the “samples” taken with the same model and to observe them at full resolution; this is valid both for verifying resistance to high ISO and, in general, for evaluating the quality level of images.
Accessories and other features to be considered
Those that we have seen so far are certainly the essential characteristics of any camera, to which are then added a long series of more or less useful options. Any type of camera is now provided with Live View, which allows you to view in real time the scene to be recorded on the LCD; not all models, however, have a swivel screen, a very useful feature when shooting from particularly uncomfortable positions, as typically happens to those who love the macro or the original perspectives.
An option that can really affect the quality of the photos is the optical image stabilizer, which compensates for the small movements of the camera during shooting and thus allows you to have clear photos even using relatively long shutter speeds, typically at dusk or indoors . Many camera models, from the cheapest to the professional, now integrate GPS support, which allows you to memorize the geographical coordinates of the place where each photo was taken; its importance is very subjective, but it can certainly be useful for travel photographers.
Virtually all compact cameras and most of the cameras in production today offer the possibility to record movies in Full HD, and the most advanced models have adopted the 4K standard; also regarding the quality level of the videos, however, it is advisable to evaluate the samples on the Web before the purchase.