As we await the arrival of our custom built light table, the digitisation of the 10x12 inch [254x305mm] Holtermann glass plate negatives is continuing on our prototype light table.
The prototype table (see left) consists of upward facing, folded fluorescent tubes inside an enclosed white area with a single diffusing layer about 950mm above. The brightness and uniformity of light delivered is near perfect, with any small shifts eliminated using a scene calibration.
The negatives are being photographed, emulsion side up, in two halves to obtain the desired resolution (at the moment approximately 12,000 pixels long). The capture device is a 50 megapixel, large format digital camera using a 120mm lens.
The two halves are then stitched together in PhotoShop to obtain a single high resolution digital master file.
The custom light table in construction will use the same fluorescent tubes for lighting, but it will be big enough to accommodate the larger glass plates and have a dedicated ventilation system to prevent heat build-up. We have also ordered a new motorised copy column that will be wall mounted and used with the light table.