1. 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

2. Scanners
Epson V700
PDS 2020 GM

3. Parameters of the scanners tested
Epson V700
PDS
Maximum Density
D~3
D=5.2
Resolution
> 12 μm
>= 5 μm
Depth of Focus
~ 1 mm
some μm
Scanning Speed
fast
slow

4. Transmission and Density1
D=lg T

5. Scanning of the negative

6. 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.

7. Interobservatory Calibration Wedge Set 38, No. 3, IIIaJ

8. Inter Observatory Calibration Wedge Set 38, No.3, IIIaJ

9. Stray Light at Flatbed Scanners

10. Gray-wedge without Silver-grain

11. MTO Gray-wedge (grainless)

12. Characteristic Curves of Kodak IIIaJ

13. Characteristic Curves of Kodak IIaO

14. CCD-Line

15. Color to Gray

16. Infrared - Blue

17. 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.

18. Recommendations
Investigations in astrometric accuracy using scans of flatbed scanners should continue.
Investigations how to use flatbed scanners on spectral plates must be done.