Sunday, August 10, 2008
Solving a parallax problem
What's wrong with this picture?
It was supposed to be a full frame picture of 4 playful rodents centered in the frame.
Why did I screw up?
The cam was too close, and I misaimed. Taking a little more time might have helped, too.
How can you miss a close-up like this?
The PIR's narrow zone of detection was aimed at the burrow, but the camera was aimed above it. This is one of the problems you encounter when you try to use a camera trap for close-ups. The center of the camera's picture frame and the narrow detection zone of the PIR are not in alignment. It doesn't matter at a greater distance.
Some commercial trail cameras use a built-in laser pointer for aiming the camera; so I just made my own laser pointing device.
This is a snap-on mount made from a hacksaw blade, and a laser pointer with a magnetized base. (They are 'posed' on my table saw). You can adjust the hacksaw blade mount and then move the magnetized laser from the PIR window to the lens window for fine adjustment.