Filter/Imaging Chip Assembly
Resting above the CMOS imaging sensor are two filters. The frontmost filter is Low-pass Filter #1 (LPF#1). The filter below it is Low-pass Filter #2 (LPF#2). LPF#2 is the "IR Cut filter" that needs to be removed. Canon made a change from previous models in that both of these filters are glued into the plastic filter frame, instead of only one being glued and the other held in place with a metal clip.
We are going to remove and replace the "IR Cut Filter" only. The "Low-pass 1" filter will be left in the camera so handle it carefully.
22. Remove two screws at the locations shown below. Lift one corner of the metal frame up with a small jewelers driver and pop the metal frame off. Be careful not to scratch the filter.
23. Now we will separate the filter assembly from the CMOS imaging chip. The black filter assembly is held on to the surface of the imaging chip by a thin strip of double-sided tape. This adhesion can be weakened by using an exacto razor knife. I used a flat "Chissel" type razor and patiently pried between the black plastic frame and the metal base, all around the unit as shown. There are two pins that position the frame correctly. Once loosened, lift the filter assembly to remove it. Place the CMOS imaging chip into a sealed container to keep it dust-free as you continue to work on the filter assembly. During these steps, make sure all optical surfaces are kept free of dust and clean with a blower's bulb if needed.
24. Low-pass filter #1 is glued inside the plastic frame at four locations shown by the yellow arrows in the photo below. Use a razor knife to cut the adhesive along the side edge of the filter glass at these four locations. Use a small flat head driver to pry the filter up as shown in the photo. Work your way around the entire filter, applying only a little pressure to work the filter free. Do not apply too much pressure in order to avoid stressing or breaking the filter. Some adhesive is under the filter's edge so the filter needs to be worked loose by prying it up. When the filter is loose, remove it, wrap it in lens paper and place in a container for protection.
25. Remove the original IR Cut Filter (blue glass) from its frame. It is glued in the plastic holder at the four corners. Use a razor knife to loosen the glue in each corner. Pry the glass up at each corner. If the filter breaks, no problem since the filter will be discarded.
26. You can use nitrile gloves to apply pressure on the filter to help remove it from its frame to avoid breaking it:
27. Glue the replacement Baader filter into the plastic frame by using very small drops of silicone glue in each corner. Be sure to use a glue that doesn't outgas as it may affect the optics. Do not use much glue here so that it doesn't run into the field of view. I left the glue dry overnight to be sure it was well cured. Below is the plastic frame with the new Baader filter glued into place.
28. Glue the original LPF#1 filter into the plastic frame by applying silicone glue at the four locations marked by yellow arrows in the photo below. There are small wells there that will hold the glue. As was done for gluing the LPF#2 filter, be sure to allow the glue to dry overnight to be sure it is well cured. Below is the plastic frame with both filters glued into place.
The disassembly and filter replacement are now completed. If there is any dust on the filter you can remove it with a blowers bulb or flick it away with a camel hair brush or the end of a microfiber lens cleaning cloth. On the next page, you can continue to follow re-assembly directions that should be easy since you'll be going through the above process in reverse.
CONTINUED Next Page - Imaging Chip Re-Assembly
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