1. Design Testing the theory Advantages Conclusion 2003 The Facts about Colortrac Open Aperture Open Aperture prevents streaks in the scanned image caused by dirt or deposits on the glass! An Open Aperture design cannot scratch the glass because there is no glass! BUT what about the effects of DIRT and DUST finding their way inside the scanner optics? WELL LET’S EXAMINE THE FACTS! The lid containing the pinch rollers and paper hold- down assembly has been removed for clarity

2. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘The Design’ The ‘Aperture’ on a Series 4 scanner is only 6mm wide All illumination and the delivery of the scanned information back to the CCDs is handled in the small area circled The CCD cameras are not positioned in the ‘gravity fall’ path below the aperture The CCDs are focussed on the media! WHAT DOES THIS ALL MEAN FOR THE COLORTAC USER? Scan path from camera(s) Media path through scanner Cross-section of the Series 4 head assembly

3. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘An experiment’ STEP 1. Take a metal wire and allow it to rest across the mirror (the mirrors could be where dust will settle). N.B. A metal wire is much larger than dust particles!

4. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘An experiment’ STEP 2. Run the scanner and look for the effect of the wire in the image Result: The wire has created a shadow or darker area but the scanner is still working! Scan direction

5. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘An experiment’ STEP 3. Now recalibrate the scanner using the white target (2 mins) Result: After calibrating the shadow has gone and the detail is still there in the arrow head! Scan direction

6. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘The Facts about dirt’ Dust/dirt on the mirrors? Any dust is not at the focal point so has negligible effect - and you don’t even need to recalibrate! Large pieces of debris will cause streaks but can be calibrated out.

7. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘The Facts about cleaning’ Ah, but what about cleaning/maintenance? Just be careful not to touch the mirrors Use compressed, dry air A lint free cleaning cloth is OK Avoid chemical cleaners It needs to be done much less frequently than cleaning the glass!

8. Design Testing the theory Advantages Conclusion 2003 Open Aperture - ‘The CCDs?’ It could fall through onto the CCDs! Mirror CCD(s) 1 pixel width The CCDs are not directly below the aperture so they are unlikely to get contaminated The chance of dust falling precisely onto the 1 pixel wide area of the mirror is virtually impossible

9. Design Testing the theory Advantages Conclusion 2003 ‘The Conclusions!’ eliminates the need to replace scratched glass stops image streaking improves the image quality by cutting reflections dirty originals can be scanned and because abrasive particles are not moved across mirrors, CCDs or glass during the scanning process they will not damage the scanner reduces scanner maintenance time Colortrac Aperture...