For my scanner photography work, I use the Canon LIDE 20. The LIDE 20 provides a useful starting point for the hardware development aspects of the scanner camera. Its relative simplicity and durability make it an easy tool to experiment with, and its low cost allows it to be modified without too much fear of expensive repercussions. In this section, I will describe a few of the simple hardware hacks that can make the LIDE 20 a more suitable imaging component for the scanner camera.
Here's a picture of a scanner, mid-modification...
Just a note for anyone who might attempt to make these modifications... BE CAREFUL! A scanner is very easy to break, and I've gone through about 20 of them over the past three years. I take no responsibility for anyone following these guidelines and breaking a scanner. With that disclaimer out of the way...
The first part of the LIDE 20 that can be modified for better photographic results is the lamp. When scanner photographs are taken with the lamp intact, the ambient light that it provides tends to drown out the light being projected through the lens, causing the captured image to become weak and washed out. Getting rid of the lamp, or disabling it, can allow a scanner camera to capture a much higher quality image.
The simplest method of disabling the lamp is destruction. Smashing the LED point source by pinching it with a pair of pliers is simple and safe, and prevents the lamp from ever working again. While this is undoubtedly an effective method of lamp removal, I don't like it for several reasons. For one, it is extremely permanent... the destruction of the LED prevents the scanner from ever working normally again. Also, it feels like an ugly solution to me; the arbitrary crushing of scanner components feels a little bit too crude.
An alternative to the destruction of the LED light source would be to cover it up. This is also an effective method of disabling the lamp, and is a little bit less permanent. The lamp can be covered with a small sticker, preferably foil-backed (in order to remove any chance of light leakage). This method has the bonus of being reversible - in order to revert the lamp back to its previous function, one needs only to remove the cover. Of course, that's assuming that no other modifications have been made...
The array of pinhole lenses that sits over the CIS sensor is an interesting design feature, and one that I think is very clever. However, since a scanner camera already has a lens built into it, these pinhole lenses reduce rather than enhance the quality of a scanner photograph. Because of this, we need to remove the array. This process is extremely easy. In order to remove the pinhole array, simply pull the lens array straight up and out of the CIS housing. Once this has been done, the CIS sensor will be exposed, and will be ready to capture the light projected by the camera lens with a minimum of distortion.
The design of the CIS housing is very simple, but it contains some aspects that become severe flaws when the scanner is used as a camera component. The biggest problem with the CIS housing is the recessed groove in which the pinhole lens array is nested. When the scanner is used in a normal fashion, this groove presents no difficulties. When used as a camera element, however, it can cast a shadow over the CIS sensor. This isn't a problem when the scan head assembly is directly beneath the lens, because the light is traveling straight down onto the sensor. Near the edges of the scan, though, the incidental angle of the light means that most (or all) of it is blocked before it reaches the sensor. This leads to a 'keyhole' format image, where a strip at the center is captured faithfully, but fades to black on either side. In order to get a better scanner camera image, the CIS housing needs to be modified.
The easiest, but least effective, way of solving the CIS housing keyhole effect is to remove the CIS housing altogether, and to attach the CIS sensor directly to the scan head assembly using glue or electrical tape. This is the simplest way to remove the keyhole effect, but has a several flaws. Firstly, it leaves the CIS sensor and some of the other sensitive electronics of the scanner, exposed to the elements. Over time, dust and scratches will render the CIS sensor useless. Also, unless the orientation of the sensor is exactly parallel to the scan head assembly, a pixilated artifact grid will appear over the scanned photograph, greatly reducing the usable resolution of the image.
Modifying the existing CIS housing is a time consuming and delicate method of solving the keyhole effect. In order to modify the CIS housing, first remove the pinhole lens array, CIS sensor, and LED prism from the housing assembly. Do this carefully, and put these components in a safe place for later reassembly. Once the CIS housing is isolated, use a small file to completely remove the edges of the canyon that houses the pinhole lens array. Try to get the edges as close to the slit at the base of the CIS housing as possible. Once this is done, carefully sand the filed areas with a fine grade sandpaper. Seal the filed and sanded areas with a thin layer of epoxy, to ensure that no dust or particles of plastic will come in contact with the CIS sensor. After the epoxy dries, carefully put the CIS sensor back into the housing and reconnect it to the scan head assembly. The keyhole effect should be greatly reduced, and the CIS sensor will be secure and properly aligned.
After performing this modification, it is advisable to attach a wide strip of black fabric to the base of the scan head assembly. This prevents the metal of the scanner from reflecting back onto the CIS sensor and creating wide white streaks across the image.
A scanned image without a reflection shield.
A scanned image with a reflection shield.