Images displayed on this site were created by Steven Gough
and Susan Pettigrew of the Digital Imaging Unit of Edinburgh University Library, 2001-2004.
Digital camera back: Phase One PowerPhase™
Resolution: 7072 x 7072 pixels
Uninterpolated files (max 143.3 Mb; min 300ppi)
56mm x 56mm frame capture area
42bit internal colour depth, 14 bit per colour precision
Native File format: Uncompressed TIFF
files with Motorola (Mac) or Intel (PC) byte order and header version 6
Capture software: Phase One version
3.1.1 for Power Macintosh
Camera body: Hasselblad 501CM
Lens: Zeiss 80mm (plus 8mm and 16mm
extension tubes for close-up work)
Capture: Power Mac G4 400Mhz/Apple 21
inch Studio Monitor with ColorSync
Post-capture edits: Adobe Photoshop
5.0 - CS
Test charts: Standard Kodak
Q13 colour separation guide (with metric and imperial scales) and grey
scale for reflected work
Lighting: 2 Photon Beard 'Highlight'
studio lights: these are cool running, flicker free, 5,400k balanced fluorescent
lamps, with a variable output of 2 tubes (110W), 4 tubes (220W), or 6
tubes (330W). This high colour rendering index (Ra 98) (2)
light source is designed for digital imaging. The lights
are fitted with Perspex safety screens.
Light levels: Using just 4 tubes per light, the measure
of Lux @ 1m = 10,666 and at 2m = 3,332. Thus at 1m for 15 minutes the
item being imaged would be subject to 2,666 lux-hrs. (By comparison, the
standard museum light level for sensitive works on paper is 50 lux. For
6 weeks display at this level (6-day week, 12-hour day) the object would
be subject to 26,500 lux-hrs per exhibition). Also, the lights are equipped
with reflective barn door units. These are employed to screen the object
from light outside the actual scanning periods, thus reducing light exposure
to an estimated 2,000 lux-hrs.
Heat rise: A preview scan is obtained in circa 15 seconds.
The scan time for a full high resolution (143Mb) image file is typically
5-6 minutes using 4 tubes per light. The rise in temperature at the surface
of the copy table during a typical 15 minute total scanning period using
4 tubes per light at 1m (i.e. 10,666 Lux) at no time exceeds 1.25 degrees
C. Tests on-site show that the temperature at the object point on the
copy table is not more than 1.5 degrees C above the ambient temperature
of the room at any time.
Archival equipment: Studio copy table with
matt black, soft velvet top surface; Clarkson book supports for bound
items (large and medium sets), plus snakes; unbleached pure cotton gloves.
____________________________
(1) These specifications conform to the Code of Practice
for the Submission of Digital Imagery as defined by the Digital Imaging
Group of the Association of Photographers (November 1999). [Back]
(2) A measure of the colour shift objects undergo when
illuminated by a light source as compared with the colour of those same
objects when illuminated by a reference source (daylight) at the same colour
temperature. The index range is from 0 (max shift) to 100 (no shift). [Back]
