ChrisN
Striving
William of Ockham would be laughing!
For the last few weeks I've been doing some shutter testing, so shooting scenes with lots of clear sky, and have become aware that my scanner was introducing some marks on the scans that didn't originate from the negs. The scanner (Nikon Coolscan V) is now six or seven years old, so it seemed reasonable to assume that it might need a spot of maintenance. Google is my friend, and I quickly found a few articles that revealed that there are a couple of mirrors that can collect dust, and some lenses and the CCD itself, and some basic instructions and a few warnings, in particular not to move the lens or touch the CCD.
The scans showed a repeating pattern of light marks that hinted at a web, so I started to think about spider webs or even fungus inside the lens. In my first attempt I pulled the cover off and accessed the mirror below the neg holder, adjacent to the lens, and found it was dusty. This is a first-surface mirror, and delicate, so I very carefully and gently cleaned it before reassembly. No difference in the scans.
In the second attempt I went in deeper. The light source on top of the neg stage has two condenser lenses and a mirror - these appeared clean but I blew out a bit of dust. Getting at the lens and the CCD meant removing the main circuit board with a plethora of wires, connectors and ribbon cables. Numerous other bits were unscrewed and carefully set aside in order, before finally the plastic cover over the lens/CCD assembly could be removed. The position of the short lens barrell was carefully noted before the retaining clip was unscrewed and the lens lifted out. That appeared clean, but I blew off a little dust; also gave the same treatment to the CCD. Nothing startling was found, reassembly went smoothly, and the tests again showed no change.
Had I missed seeing fungus growing inside the lens? Another exploration was called for. Finally, when reviewing the faulty scans, a light came on inside my dim head. If there was something in the optical path that was appearing on the scan, it had to be reasonably close to the focus point - which means close to where the negative sits. The neg holder is a device that plugs into the main body of the scanner and moves a strip of six negs back and forward. The neg holder is the first thing removed and set aside before disassembing the scanner.
I pulled out the neg holder and held it up to the light. Guess what I found - spider web across the gap immediately below the negative!
The moral of the story? Start with the simplest possible assumptions regarding the problem, and move on to more complex only when essential.
Cheers!
For the last few weeks I've been doing some shutter testing, so shooting scenes with lots of clear sky, and have become aware that my scanner was introducing some marks on the scans that didn't originate from the negs. The scanner (Nikon Coolscan V) is now six or seven years old, so it seemed reasonable to assume that it might need a spot of maintenance. Google is my friend, and I quickly found a few articles that revealed that there are a couple of mirrors that can collect dust, and some lenses and the CCD itself, and some basic instructions and a few warnings, in particular not to move the lens or touch the CCD.
The scans showed a repeating pattern of light marks that hinted at a web, so I started to think about spider webs or even fungus inside the lens. In my first attempt I pulled the cover off and accessed the mirror below the neg holder, adjacent to the lens, and found it was dusty. This is a first-surface mirror, and delicate, so I very carefully and gently cleaned it before reassembly. No difference in the scans.
In the second attempt I went in deeper. The light source on top of the neg stage has two condenser lenses and a mirror - these appeared clean but I blew out a bit of dust. Getting at the lens and the CCD meant removing the main circuit board with a plethora of wires, connectors and ribbon cables. Numerous other bits were unscrewed and carefully set aside in order, before finally the plastic cover over the lens/CCD assembly could be removed. The position of the short lens barrell was carefully noted before the retaining clip was unscrewed and the lens lifted out. That appeared clean, but I blew off a little dust; also gave the same treatment to the CCD. Nothing startling was found, reassembly went smoothly, and the tests again showed no change.
Had I missed seeing fungus growing inside the lens? Another exploration was called for. Finally, when reviewing the faulty scans, a light came on inside my dim head. If there was something in the optical path that was appearing on the scan, it had to be reasonably close to the focus point - which means close to where the negative sits. The neg holder is a device that plugs into the main body of the scanner and moves a strip of six negs back and forward. The neg holder is the first thing removed and set aside before disassembing the scanner.
I pulled out the neg holder and held it up to the light. Guess what I found - spider web across the gap immediately below the negative!
The moral of the story? Start with the simplest possible assumptions regarding the problem, and move on to more complex only when essential.
Cheers!
Attachments
MartinP
Veteran
That sort of reminds me of the story of the early astronomer who allegedly reported seeing elephants on the moon. It was later found that there were mice in his (huge and primitive) telescope . . .
The cleaning was a useful thing to do though!