The human eye can perceive approximately 24 f-stops when considering the pupil opening and closing in relationship to the light coming in. In contrast, the highest dynamic range a digital camera has achieved so far, is 14 f-stops. To span large ranges of greyscale values, you will either need to create a HDR image or use a scanner with a Multi-Exposure algorithm that does the same for film.
The other day, when I was scanning old negatives with a new Canoscan 9000F MK II and SilverFast 8 for my piece on SilverFast’s Multi-Exposure, I kept thinking about the reasons any photographer should want to keep using film and a scanner to digitise his or her images instead of using a digital camera. That made me contemplate some of the disadvantages and benefits of scanning film and those of image sensors…
During the years I had my dark room (the real thing), I remember I had to burn areas to get a better exposure across the photo. It was the analogue version of trying to achieve a high dynamic range — high enough at least to represent most brightness values across a photo based on what the film emulsion was capable of. Today, with a scanner, the dynamic range of any scanned photo is not just limited to capabilities of the film emulsion but also by the dynamic range of the scanner itself. It’s as with digital cameras: there are only as many f-stops available as the sensor will “see”. Just as with digital cameras, you can achieve a higher dynamic range by combining an exposure for highlights and one for shadowy areas. This method works only with scanners that allow this “manipulation” and the right software to work it. SilverFast is by far the best application with which you can apply this technique, having been awarded the European Digital Press Association’s “Best Colour Management software of the Year” prize in 2008 for it.
DxO Labs has once again upgraded its flagship image editor, DxO Optics Pro. Version 9 has a re-designed interface, a unique noise reduction feature, better DxO Smart Lighting capabilities, new visual presets and new and improved export tools. From my own testing, this version could well be the one that makes all others bite the dust.