Use Your Camera To Capture "3D" Anaglyphs

Step 3 Determine The Mount Diameter For The Stop

You are going to make an aperture stop that will be placed in front of your lens, not unlike the stops other instructables have suggested for bokeh shaping. However, precision matters more here, so we're going to go through the technical steps to maximize the probability that it works for you.

Fisheye and other ultra-wide-angle lenses often have bulbous front elements that don't provide a simple front-mounting option for a new stop. You can't use one of them unless you put the stop elsewhere, and that's beyond the scope of this instructable. Sorry.

For many lenses, there is a thread for screw-in filters. If your lens has that, note the filter thread diameter marked. Relax; mounting will be neat and easy.

If your lens doesn't have a thread (most compact camera lenses don't), use a ruler to measure the diameter of the rim around the lens. Be careful to measure only the portion that moves with the front glass element for an extending lens, not the diameter of the whole assembly. We will treat this number as your filter thread diameter, although mounting will be less elegant, perhaps using a little sticky tape.