Railfan Technology > BW Scanning: get the most out of a scanner

While processing my BW negatives I noticed that my scanner (Nikon Super coolscan 4000)  was not able to always cover the entire black and white dynamic range in a single scan. That is, there is more dynamic(light-dark) information in a negative than the scanner can recover). This was especially obvious for negatives with great contrast. While processing software helped to recover some of the loss, the results were not always satisfying, often resulting in a grainy recovery.

The obvious solution is to do multiple scans, each covering a a portion of the dynamic range, and blend the different scans using available software (like HDR, or the poor mans version, extended dynamic range, ER) .  Unfortunately there does not seem an easy way to over ride the auto exposure and adjust the exposure manually (if you know a way, please let me know, software to adjust does that after the scan and that would defeat the purpose here). However, BW films are scanned in a holder so that up to three negatives can be scanned, and only the exposure of the first negative is measured. By substituting either a dark (to over expose) or a light (to underexpose)  single negative (I use some scrap negatives with different density) it is possible to obtain different exposure of the next two negative pictures in the film holder.

I process the different exposures (usually two, sometimes three) by loading them into layers in PS, and use the ER procedure to erase the area that needs replacement in one layer so that the darker (or lighter) second layer shows through.

Picture 1: auto exposure
Picture 2: darker exposure obtain by having the auto exposure done on a darker negative
Picture 3: Extended dynamic range by combining picture 1 and 2, note how the clouds in the sky show up, the mountain is darker, while the train actually is lighter. In this case I also used an overexposed negative to highlight the Westinghouse drive of the engine.

Thomas Eckhardt


 

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Nikon Scan is horrible for B&W with a Nikon 4000 scanner. VueScan does a better job witrh the same scanner.
Rich