At this stage of digital cameras, I realise that many manufacturers, if not the majority, bet more on the quantity of pixels rather than the quality of the pixels. Even at most of the photographic agencies with which I work, which are not few, they prefer large images in JPG format, worked and retouched beyond acceptable limits; even washing all kinds of grain, showing a soft, unreal, image without detail. From my extensive experience in the digital world, and especially in the photography one, I always have bet more on the quality than on the quantity.

At present, manufacturers sell us more pixels inside their cameras, alleging that that gives us greater quality; but if the sensors of the digital cameras all have the same size, this means that the photoreceptors have to, obligatorily, be smaller when offering us more resolution. This decrease conditions that all the photoreceptors are filled more quickly with light, and therefore, the dynamic range of our photos becomes smaller.

In photography, the dynamic range is one of the most important characteristics when we speak of quality. Some manufacturers bet on building sensors of the complete still size, for which their receivers have a greater depth and they are filled more slowly, promoting the dynamic range.

The ideal thing would be that digital sensors would reach a high dynamic range, equivalent to the tonality of the film. But it is complicated to preserve the details of the lights in scenes with a contrast between normal and high, when we are offered sensors of the same size but with greater resolution. If the manufacturers enlarge only the resolution without enlarging the size of the sensor, we end up with a greater number of photoreceptors of smaller sizes, for which each one of them will be filled with light more quickly, creating a photography with greater size but with less dynamic rank; that is, with less quality.

If we desire to discover the dynamic range of the sensor of our camera, and we do not have a professional material to do it, I advise you to photograph a gray card or another surface of neutral colour with different expositions, but always with the same light. The starting point is a photography of standard adjustment in manual or automatic way, which will establish the medium point for us. Next, photographs will be taken at regular intervals, lighter and darker, at least 6 takes in each direction, underexposing and overexposing. Ideally, they should be taken at intervals of 1/3 or half a number f. Subsequently, we will unite all the images in Photoshop or another program of similar characteristics. Now, we will measure the values with the cursor and the information screen. To not get muddled up with RGB and CMYK values, we can put the Information palette in measurement of a single tone, for which it will only give us a single value of ink. We will measure the step of the left and we will seek the one that has value 5 (a smaller value would give us black), and we will measure the steps of the right until finding one with value 250 (an upper value would give us white). Those are the two extremes of the dynamic range. We will count the steps that there are between one extreme and the other, and supposing that we have counted 9 steps we will have a rank of 8 numbers f for our digital camera. Following this, one must verify if the medium point of these 9 steps coincides with the average exposition of the camera. If it does not coincide, we will discover if the average exposition of our camera overexposes or underexposes. Knowing this, we will be able to correct the average measurement of our camera applying the exact value.

If we desire to take the greatest dynamic rank in our photographies we should always work in Raw and to try to trust the hystogram of the camera. If the histogram is very dominated by the shadows, it is preferable to try to manage to displace it as much as possible to the lights without coming to burn the three RGB channels. In Camera Raw it is easy to recover detail of the lights, as long as it is not burnt. There are others who advise to work in the shadows and media tones, but if we do not have digital cameras of large sensors, this is an error, since the noise increases in cameras of small sensors of duplicator factor 1,6. Provided that we remove noise in Photoshop or another software, we will lose vital information and detail.

Summarising. The sensors that increase in resolution but do not increase in size, have a worse quality of image.

Nando Rivero
Photographer and Technician in Digital Laboratory of the Agency Cover
Bachelor in Fine Arts, modality Digital Image and Photography.
Master in Digital Image