The resolution of the camera sensor is one of its most important parameters. To a large extent, it determines how much detail your photo will have in the end and how much you can enlarge it for printing later. Every sensor contains a certain number of photo detectors which determines image resolution. For example, a 24 mp sensor used in many ILC brands and models has a ratio between the sides of 3:2 and physical dimensions of 36x24mm. It contains 6000 active photo detectors along its length and 4000 along its width or a total of 24 million photo detectors. Following this logic, with this camera model we can shoot a picture which will consist of 24 000 000 different picture elements or as we are more used to calling them – pixels.
The logical question to follow is – how many megapixels do I need to have a sharp and detailed photo? There is not one definite answer to this question because it all depends on the size we have chosen for our print and the viewing distance. If we have decided to shoot only for the family album and we print sizes not bigger than 10×15 cm, then even a 2 mp camera will completely meet our needs. If we want to print copies in A4 (20x30cm), then we will need a camera with at least 3 or 4 mp. While a picture in size A4 is viewed from a distance of less than 1 metre, a large billboard is viewed from a distance of 20-30 metres or more. Often a 4 mp resolution is sufficient to print a billboard. Of course, and I can never say this too often, in order for you to have good quality photos, your camera must be equipped with a good lens. The combination of lens and sensor is more important than the number of pixels itself. A 12mp camera with a large 24x36mm sensor and a good lens will produce an image with much higher quality than a 24mp telephone with a 4×6 mm sensor and a small inbuilt lens. One of the things you should look out for when buying a digital camera is the so-called interpolated resolution. This resolution, which some less responsible brands advertise as the main resolution, is derived by means of software intervention and is nothing more than an image, which has been artificially expanded by the programme – something you can later do on your computer.
Regardless of how many megapixels your camera has, it must offer the possibility to shoot at lower than maximum resolution. Using this option, when you only take photos of documentary value not meant for printing, you can use the lowest camera resolution. When you shoot for the family album, 6 mp will be more than enough, but when you take more artistic images and you want to print them in larger size formats, you can use the maximum resolution. It is easy to calculate what resolution you need based on the specific size of the intended paper copy. All you need to know is that to have a good paper print for amateur purposes, you will need an image with at least 200 pixels per inch (2.54 cm) of the paper copy. This means that if you want to print photos on 10x15cm paper (4×6 inches) with good quality, you should provide a file with resolution 800×1200 pixels. In order to have perfect quality, you will need 300 pixels per inch (300 ppi) or a file with resolution 1200×1800 pixels (2mp).
Over the last year memory card prices have dropped significantly. Having sufficient storage memory at hand is no longer an issue. In this context, the best solution is to use full resolution and lowest compression or the highest quality which the camera can offer. It is easy to delete an unsuccessful photo right from the camera, to reduce its resolution or even cut only the part we need in order to free up more space on the memory card. However, it is impossible to increase the quality of a photo taken at low resolution settings. There is another serious argument in support of the premise that you need to shoot at the highest possible camera resolution. Often in a hurry we do not manage to compose the picture properly and if the image is large enough, we can cut out any extra parts and still be left with a file which has enough resolution for a good quality print. It is even possible to split a photo in two and have two new completely different images. In practice, if we are aiming for a 20×30 print, it makes little difference whether you shoot with a 12, 16 or 24mp camera. The differences will be invisible for the naked eye. Having a high resolution, however, will give you the opportunity to magnify and crop your images. If you use a 24mp camera (6000×4000 pixels) and a lens with focal length of 85mm, you could use cropping and twofold magnification to have the same image you would get with a 170mm lens and resolution of 3000×2000 pixels or 6mp, which will be enough for an A4 print. And if we have a camera featuring the new 60mp sensors, then the twofold magnification will leave sufficient resolution reserves for further editing – 15mp. In this way high resolution cameras could spare you the need to change lenses if you want to zoom in on a far-away object.
The following two photos were taken with a macro lens and a high-resolution camera. With such a combination you can achieve magnification with quality equivalent to that of a microscopic image. In the first photo you can see a detail from the small seconds dial of the watch and in the second one you can see the cutting edge of a knife.
The photographer is not simply the person who records the past, but the one who invents it.