Choose a film scanner: useful information

To transfer negatives or slides to digital format, use a special device - a scanner for the film. It differs from the conventional scanner in that it is designed to process small transparent images that have a high resolution. Although many flatbed scanners are equipped with special modules that allow you to scan slides, but the product obtained as a result is not of high quality.

Only CCD (CCD) scan elements can provide the required depth of field for high-resolution images. Therefore, all film scanners are built with their use. Some models have one CCD line. In this case, a triple pass of the negative is required for digitization. This prolongs the scan, but does not affect its result. In general, the film scanner has a CCD matrix, and the image is digitized in one pass. Some models use a reusable pass to reduce errors in the resulting image.

An important parameter, which is worth paying attention to when choosing a scanner, is the optical resolution. The width of the most common film is 35 mm, and the image itself is even smaller. Therefore, the optical resolution should be at least 2400 dpi (dots per inch). There are scanners that provide 4800 and 5400 dots per inch. And although today's level of technology allows to achieve even greater values, it is inappropriate - the grain sizes of even a fine-grained film will be much larger than a pixel.

Particular attention should be paid to the dynamic range or optical density. The higher the value of this parameter, the better the scanner for negatives can transmit halftones and smooth color transitions. For high-quality processing of the film, the optical density should be in the range from 3.2 D to 3.6 D. There is no point in acquiring models with more optical density, since the overwhelming majority of films have precisely such values.

The quality of digitization is influenced also by the bit depth of the representation of light, which characterizes the color rendition. A modern film scanner can have 42 or 48 bit color representation, but processing in this format is used only inside the scanner and serves to reduce the "noise" of the conversion. The resulting image has a 24-bit color encoding standard for computer hardware.

The slides scanner is in most cases connected to the computer via a USB interface. More expensive models can be connected via SCSI-2 and IEEE 1394 (FireWire). In this case, often enough in the package there is a board with this controller.

A film scanner almost always has hardware for image enhancement. This is Digital ICE, which allows you to remove dust and scratches from the image without affecting the main image, and Digital GEM, which eliminates the graininess, and Digital ROC, which allows you to restore colors in faded photos, etc. Quite often, all these tools are combined in one package Digital ICE4 Advanced. Using these technologies significantly prolongs the scan, but the result is excellent. For similar transformations in Photoshop will take much more time, and the result is by no means guaranteed.