Back in the days of aluminum bodies and optical glass, zoom/telephoto lens bodies incorporated a tripod mount to help balance the heavy lens/camera combination on the tripod. With the advent of "plastic" bodies and "plastic" lenses, albeit of superlative quality, the lens are now so light in comparison that, in many cases, the built-in tripod mount has gone the way of the dodo bird. Even with lighter weight cameras, there is still a problem of unwanted movement when using a long lens on a light duty tripod because the mount on the camera acts as a fulcrum, magnifying any apparent jiggle or motion. (Yes, these newer lenses have vibration reduction, but that eats up f-stop.) In addition, if one desires to shoot a photo in a vertical format, the tripod head must be adjusted. My design, easily changed if one knows Autodesk Inventor, solves both problems by repositioning the tripod mount and allowing for full, 360 degree, rotation of the camera.
Step 1: Canon DX AF-S Nikkor 55-300mm Tripod Mount
1. 1/4-20 x 5/16 T-Nut
2. Epoxy putty or pourable epoxy
3. Gel-type adhesive
4. Four (4), #2 x .75" sheet metal screws
Nice to Have Things:
1. #43 or larger drill (but not too much larger)
Step 2: Lens Mount External Ring
The core of the mount is the external ring which incorporates the T-nut. I designed it to take advantage of the utility of the 3-D printing capability at my local technical college, Athens Tech, Athens, GA, where I am now enrolled as a student. Since the final part is made from extruded ABS plastic, I felt that I would need a more substantial metal component for the threaded mount since an ABS internal thread will strip out over time. I also incorporated a ledge, profiled for the Nikkor lens, which bears the weight of the camera body without torquing the lens ring. For added strength, I extruded an internal cavity, to be filled with epoxy, to support the stress placed on the T-nut.
Mounting the T-Nut is quite simple. Have a pair of pliers handy. Heat the nut on the stove. Give it a couple of minutes to heat up. Remove the nut from the stove with the pliers and place on a surface, preferably the stove top. Press the external ring on top of the nut. Use some pressure! The nut will melt its way flush with bottom of the External Ring Mount.
Back fill with your favorite epoxy putty or liquid epoxy. I prefer the solid putty for this application. It does require stuffing into the cavity, but it's denser and harder than the pourable kind.
Step 3: Internal Ring
The internal ring features a couple of unique design features to increase its functionality. First, the lens has a depression and a raised area around the body where the ring will seat. I designed corresponding features in the ABS ring that are highlighted in red. This means that the ring aligns with the corresponding features on the lens body. Second, the ring is designed to separate into two parts, but only one joint releases easily. The ring expands slightly making positioning on the lens body very easy. Finally, both sides of the ring are keyed to ensure proper alignment.
Open up the top holes with the drill bit to allow the screw to slide through easily. I guess I should have designed that feature into the part!
Apply a small dot of your preferred adhesive to only one spot on the lens body. Move the ring into position, aligning the depression and raised areas of the lens body to the ring. Once you fasten two of your #2 screws, the joints will close securely. The adhesive only serves as a backup to keep the ring in position.
Step 4: That's All Folks!
When you screw the external ring together, be prepared to shim the gap to suit your tastes. Once again, you will need to enlarge the top holes with the drill bit. You can actually screw the upper and lower ring so tight that the camera will not rotate. Experiment to arrive at just the right amount of friction to hold the camera at any angle, yet loose enough to rotate with ease.