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Photometric Accuracy of Flatbed Scanners Compared to PDS Microdensitometers. Dr. Renate Budell. Institut of Astronomy, Bulgarian Academie of Sciences. Physikalisches Institut, Westfälische Wilhelms-Universität Münster. e-mail: budell@wwu.de. Scanners. Epson V700. PDS 2020 GM.
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Photometric Accuracy of Flatbed Scanners Compared to PDS Microdensitometers Dr. Renate Budell Institut of Astronomy, Bulgarian Academie of Sciences Physikalisches Institut, Westfälische Wilhelms-Universität Münster e-mail: budell@wwu.de
Scanners Epson V700 PDS 2020 GM
Parameters of the scanners tested Epson V700 PDS Maximum Density D=5.2 D~3 Resolution > 12 μm >= 5 μm Depth of Focus ~ 1 mm some μm Scanning Speed fast slow
Transmission and Density I T= I0 1 D=lg T
VueScan • VueScan is an alternative to the usual scan programmes delivered with the scanners. • With VueScan one can get unprocessed data (raw mode) • VueScan is a program, not a driver. It is not possible to use it together with FitsScan. • Output in raw mode is possible in Tiff format only.
Conclusions • Photometrie with Flatbedscanners goes wrong while scanning photo plates with silver grains. If density is higher, the error of photometrie is bigger. • PDS Microdensitometers should be kept working when scanning in high presition.
Recommendations • Investigations in astrometric accuracy using scans of flatbed scanners should continue. • Investigations how to use flatbed scanners on spectral plates must be done.