Extend The Limits Of Film Scanning; LaserSoft’s SilverFast Multi-Exposure Increases Effective Dynamic Range Page 2

I made the series of scans after color correction and adjustment first without Multi-Exposure and then with Multi-Exposure turned on. I began opening both scans, with and without Multi-Exposure, side by side in Photoshop. The non-Multi-Exposure scans limited my ability to lighten the shadow density without flattening the contrast and saturation. However, I found I could go further with the Multi-Exposure scans. Shadow detail came up brighter and more saturated, plus I could maintain a dense black at maximum density. Of course, information potential has to be in the image to begin with, and no amount of manipulation will reveal detail in a shadow that is below the film's D-max. I must also admit that recovering shadow detail to a printable level that matches the character of the middle values in a Kodachrome scan using Mutli-Exposure requires quite a bit more exact tweaking than with E-6 films. But Multi-Exposure provides the depth of information to achieve a more favorable overall result. And anything that makes Kodachrome scanning less difficult and frustrating is appreciated.

This scene in northern New Mexico was made on a preproduction version of Kodachrome K-14 process film. The film image is very contrasty, the result of a clear sunlit day at high altitude, but also contains a strong cyan processing color shift. It has been a valuable test image for scanning to evaluate the corrective capabilities of scan software. Using the new SilverFast Ai 6.5.1 with Multi-Exposure I was able to obtain the most neutral color correction yet. With adjustments I could remove the cyan color cast as well as obtain exceptionally fine quality shadow detail under the eaves of the storefront.

Fluid Mounting 35mm Slide Film For Scanning
The reason for fluid mounting is that fluid causes the film and interior glass surfaces to effectively disappear, to become transparent to light passing through; thus, the sandwich of film between two pieces of glass behaves as if it is a solid with only two exterior surfaces exposed to air instead of a total of six surfaces exposed to air. Surfaces exposed to air reflect light and, if not perfectly smooth and free of irregularities, can diffuse and misdirect the light passing through the surface. Film and emulsion surfaces are also somewhat porous, furthering the amount of light diffraction and diffusion. So film in fluid between glass sheets can actually provide superior light transmission accuracy compared to film surfaces alone exposed to air.

The physical/optical advantages of fluid mounting are well established by drum scanning; only the physical aspect of creating an effective mounting of 35mm film in fluid without any air bubbles remained a practical, technical challenge. Professional drum scanning requires fluid mounting of film on the drum cylinder with a sheet of optical plastic creating the outer surface of the sandwich. This well established procedure has provided us with scientifically-formulated mounting fluid that makes mounting easy and effective. The fluid recommended is KAMI Mounting Fluid, sold and distributed by Aztek. A full description of the Mounting Fluid as well as useful film and drum cleaning solutions is available at: www.aztek.com/consumables.html.

This site also includes an online store for direct purchase of the needed supplies. I would also recommend the KAMI Film Cleaner fluid. Lintless wipes that will not scratch film are available from Aztek.com and most pro photo suppliers.

One necessary item that may prove elusive and difficult to find is 2x2" slide cover glass. It was made by both Leitz (U.S.A.) and Kodak, but apparently has not been manufactured for some years. However, some supplies do exist in some corners of the photo world, as I found a box of new Leitz cover glass on eBay offered by Zeff Photo Supply of Belmont, Massachusetts. You will also need some film that is the thickness of 35mm slide film, but at least 2x2" in area. Some European and Japanese 120 films were coated on a thicker stock that I found close enough. And finally, you need tape to hold the glass/film sandwich together; I found that plastic electrical tape, because it is rather elastic, holds the glass tightly.

This view of mountain aspens high in the Colorado Rockies with a mining millpond in the foreground has been one of the more difficult Kodachromes I have attempted to scan. The challenge is to obtain a natural reproduction of the color, both in the copper-colored pond and in the sky, while obtaining the detail and neutral values of the aspen trees on the side of the mountain. The new SilverFast Multi-Exposure extended the range of values scanned and yielded accurate fidelity to the original, something that had eluded me for sometime.

The mounting technique involves first cleaning the cover glass and the film carefully and thoroughly. Then, out of the larger (120 size) film cut a square 2x2" with a window for the 35mm film frame, but with the sprocket holes on the sides trimmed off. Yes, trimming the 35mm slide film image to remove the sprocket holes is a necessity as the sprocket holes tend to trap air bubbles in the mounting fluid. Once you have all the components ready, use an eyedropper to put some KAMI Mounting Fluid on the bottom cover glass, put the film mask in place, and then, inside its frame, the trimmed slide film frame. Add more drops of KAMI Mounting Fluid on top and then put the second cover glass sheet in place. Apply gentle pressure to squeeze the glass plates together and then seal the edges with electrical tape. Finally, place the 2x2" fluid-mounted sandwich in your scanner and scan immediately (KAMI Mounting Fluid is very volatile and will evaporate rapidly).

Conclusion And Recommendation
The latest version of SilverFast (www.silverfast.com) contains many new features that aid users in getting better image quality from their scans. While one interesting feature of this upgrade, Multi-Exposure, works fine with the Nikon CoolScan, you will have to use the workaround described to avoid ghosting with some other scanners. The fluid mounting method I described probably can be refined further, and be made advantageous for those who want to push for the ultimate ideal in scan quality.

Fortunately, the Version 6.5 upgrade that includes Multi-Exposure can be acquired in the SilverFast SE Plus version for as little as $35 for anyone with a licensed copy of SilverFast SE, and somewhat more for users of SilverFast Ai. Pricing does vary relative to the brand and model scanner so visit the SilverFast website for the specifics. If you are just curious if what I have described will work for you, and to check on results with your scanner, a demo version of SilverFast for most scanners can be downloaded from their site at no charge. (You can get an instant link to the download page at the Shutterbug Co-Op at www.shutterbug.com.)

For more information, contact LaserSoft Imaging, Inc., 3212 Gulf Gate Dr., Unit B, Sarasota, FL 34231; (941) 921-4815; www.silverfast.com.

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