Howto: Camera Tripod PVC Extension Pole for Eye One Pro Front Projection Calibration

Sunday night, I stayed up late calibrating my Sanyo PLV-Z3 LCD projector. I attempted a full gamma and grayscale reading from 0–100% using GetGray‘s 10% increment gray window test patterns. The Eye One Pro can only get reliable sub-30% grayscale readings when you point it directly at the projector with the ambient light head attached (as opposed to the usual emissive readings from the light reflected off the projection screen).

Now I have a problem. My projector is mounted on the ceiling, a little under seven feet off the ground. My camera tripod—that would normally hold the Spyder2 Pro or Eye One Pro—only extends to about five feet high. I had to find a solution to getting the Eye One two feet in front of the projector and fully bathed in the light path so I could sit at my Powerbook and take readings in Babelcolor. I needed to mod my tripod.

After dismissing ideas to screw a hook in my ceiling (that would leave an ugly hole when I was done, and my wife is already fed up with the projector, mount and flush speakers decorating our basement ceiling), I figured I could replace the short tripod extension pole with a longer one to achieve the required height. I imagined PVC plumbing pipe would be cheap enough to try.

Once I had the tripod extended with its new neck I could simply attach the Eye One Pro, uh, somehow.

Supplies:

  • Cheap camera tripod with removable center head extension pole: You don’t need the latest carbon-fiber-gyroscoping-stable-job here, just whatever is cheapest at your local super department store. Make sure it has an adjustable and removable cylindrical head extension.
  • ~5 ft. 1/2 in. PVC plumbing pipe: Unless you deal with PVC pipe for a living or a hobby, you probably don’t have the special tube cutter the Home Depot guy used on my 10 foot long tube. He cut the tube in half both so I didn’t have to cut myself and so I could fit it in my car (alongside a rake and 12 bags of mulch—the real reason for the Home Depot errand). Five feet worked for my tripod, you may need more or less depending on the projector’s placement in your room.
  • PVC 4 way intersection connector: I initially thought I could use Velcro straps to secure the Eye One to the pole (see armature wire below), so I need some type of head on the pole to wrap the straps around and cradle the Eye One Pro’s odd, bulbous and phone receiver-like shape. After looking through the dozens of PVC tube connector boxes I settled on the four way cross connector. I would have rather used a right angle Y connector as it would stop the Eye One from rocking side to side whenever I had to replace the ambient calibration cap. Maybe a plumbing supply store would have that connector (plumbing supply store are dangerous, giving my wife way too many remodeling ideas).
  • Heavy Guage Aluminum Armature Wire: Your local arts and craft store should carry spools of this wire meant for the skeleton of Sculpey Unicorn sculptures (I cannot think of any other possible use). The wire will secure the Eye One Pro to the head piece of the pole.
  • Plastic hook with sticky backing: When I wired up the Eye One to the head of the extension pole it had bad posture, pointing toward the floor instead of straight at the projector. The plastic coat hook stuck to the PVC pipe and held the bottom of the Eye One out from the pole angling its head toward the projector.

Construction:

  1. Remove the camera tripod’s normal center extension pole by unscrewing or releasing it set screw or pin.
  2. Attach the PVC cross connector to the pipe until it is tight. You shouldn’t have to glue the two pieces together.
  3. Insert the PVC pipe into the top center hole in the tripod. Tighten the set screw until the pipe cannot move up or down. If the set screw cannot hold the pipe in place you must have bought the wrong size pipe.
  4. Cut and 24" length of armature wire and match up each end evenly in a U shape like you would do with shoe laces. Wrap the wire once around the center of the Eye One and then under its bottom two feet, then around the center again. You should end up with 4-6 inches of wire left on each side pointing toward the back of device. You want to make a cradle for the Eye One, kind of like a plate holder.
  5. Lower the pipe head to eye level to attach the armature wire protruding ends into the left and right sides of the cross connector head. Squeeze each side of the wire until it forms around the sides of the Eye One and makes a slight pinch in the space between the Eye One and PVC head.
  6. Dry fit the wall hook to find where the Eye One sits vertically (head pointing toward your projector lens). Stick the wall hook to the pipe in the place you eyeballed.
  7. Attach the Eye One’s USB cable first to the device and then to your computer.
  8. Turn on your projector. Place the tripod with the Eye One two feet in front of the lens. Adjust the height of the extension pole until the top of the Eye One’s shadow is in the center of your projection screen. The head should be completely bathed in light from the projector.
  9. Calibrate the Eye One with the ambient cover. Carefully remove the cover. This may shift the whole contraption a bit depending on how tight you could get the armature wire. With a light touch adjust the Eye One until it is again pointing toward the lens.
  10. Fire up your calibration data collector software (Babelcolor or Accucal) and start taking measurements.

The whole tripod is cheap and wobbly but in normal operation this shouldn’t affect the quality of your measurements. The PVC pipe and connector only cost a few dollars and I had everything else in my junk drawer. Plus you’re not permanently changing or damaging the tripod or Eye One, so you can take the contraption apart and let the components serve their usual purposes. So this was a quick and cheap way to get my Eye One high enough to take measurements in front of the ceiling mounted projector.

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