Mounting CC filters

Since CC filters seem to be here to stay, it's time we found a decent way of mounting them. What we want is a mechanism that is simple and cheap and allows the filter to be easily removed and replaced as necessary. Having tape or tac or anything sticky near the lens is not good, especially if you are frequently experimenting or trying to show somebody the before and after comparisons. Trust me, you don't want to touch your lens with the sticky side of electrical tape.

Today there are several very successful methods of mounting CC filters. One difficulty is that the Optiflex 100 filters are square, but they can be cut into a circle and mounted inside a lid (from a container) to make a very attractive piece. Popular sources of lids include, one pint ice cream containers, sour cream containers, and stove top stuffing containers. If you want to try this yourself, check out Dana's web site here for detailed instructions, Otherwise, you can buy a CC filter premounted from the SMART Products Store. The picture above shows how nice these filters, manufactured by Steve Shubick, look when placed on the projector (mine).

If you want to mount the filter uncut, here is something I tried, and it works well, but does not look nearly as nice as the round mounted version.

The idea is to glue several pegs or small posts onto the filter spaced at the outer diameter of the lens. These pegs then provide a slip-on mounting allowing easy removal, etc. The picture below shows a filter with the pegs in place as well as several of the things necessary to build the assembly.

The small plastic pegs were obtained by amputating the end off of a drip watering device - a "dripper", that is readily available in hardware stores (at least in California) at very low cost. You can see one intact "dripper" just to the right of the filter. The diameter of the pegs obtained from the drippers is 3/16 of an inch and any other source of plastic rod or tubing of a very similar diameter should work as well. The process is as follows:
1. Buy a bag of drippers
2. Cut of the black end from one.
3. Find the peg that you cut off on the floor, if possible.
4. Repeat steps 2 and 3 until you have 4 pegs.
5. Place the filter on a clean flat surface.
6. Place the projector's lens cap centered over the filter.
7. Using a fine-tipped felt-tip pen, preferably red, draw small arc in the 4 corners as close to the lens cap as possible.
8. Place a very small drop of Superglue, or other suitable adhesive, in the center of one of the arcs
9. Place one of the pegs on the drop of glue and position it carefully so that the center of the peg is right over the arc or line that you drew in step 7. Make sure you place the uncut end down so that the peg will sit perpendicular to the filter surface. Repeat for the other corners.
10. Let dry thoroughly. 10 minutes should do it, but check it because you really don’t want to permanently glue this assembly onto the projector.
11. Carefully place filter assembly on lens, obviously making sure that all four pegs go on the outside of the lens.

The slip fit will be a bit loose, but that is fine, as the filter will lay flat and centered on the lens as shown above. Unless you projector is pointing downwards the filter will stay in place. If you try and decrease the spacing to get some tension on the pegs, it will slightly distort the filter. Pegs of this diameter with their centers mounted at the OD of the lens cap seem to be just about perfect in their spacing. No doubt though, the mounted round filter sold on the SMART Products Store looks much nicer.