How to stop wooden structures changing shape when the weather changes?

[Simon]

Hello -

I've installed a webcam on the side of a wooden barn. The webcam has a long lens (equivalent to a 750mm lens on a 35mm camera), and changes in temperature and humidity seem to cause the barn to flex, and the webcam no longer points in the direction I want it to point. Here's a picture of the camera and the website:

barn walls are made from boards with a cross-section of about 15mm x

150mm, and the camera is bolted to these. I'm looking for a way to reduce the shape changes in the barn when the weather changes. My ideas so far are: 1) Install some 3m x 50mm x 100mm beams inside the barn wall, bolted to the steel frame of the barn, and bolt the enclosure to these. 2) Paint the woodwork with waterproof paint, so that it's moisture content would not vary so much. 3) Install some 3m steel beams inside the barn wall, bolted to the steel frame of the barn, and bolt the enclosure to these.

Presumably wooden beams would still flex, but being thicker and not directly exposed to the elements, the flex would be less. I guess steel would be better still, but more expensive and harder to work with.

Any comments would be appreciated.

Simon

[PC Paul]

Congratulations on an interesting problem!!

If it was me I'd go the extra step and make the camera remote controlled, preferably via the web ;-)

But, practically....

It looks as though the camera is mounted in the middle of a wall, where the flex will be greatest. can you mount it nearer to a corner?

[andrewpreece]

Don't fight nature: wood moves. Fix the webcam on a steel structure, either outside, or emerging from inside the barn. IMO.

Andy

[Ian Stirling]

Simply enclose it in a larger building, and run humidity control. Problem solved.

[Rick]

Steel still moves - expansion and contraction.

With a lens that big, it won't take more than a tiny movement to move the picture, the movement could come from many places. Wind may be a significiant factor.

Rick

[Andy Mckenzie]

How about some form of compensating mechanism that tilts the camera? Some video conferencing cameras will automatically follow a target (might need to be a bit nearer than Lundy), or something purely mechanical, I wondered about a heavily weighted set of gimbals (heavy to avoid being moved in the wind!) perhaps even a wire to a fixed point on the ground that pulls the camera in opposition to any movement of the barn.

Andy

[Simon]

x

It seems that the wind is not a big problem - the camera only moves during strong gusts, and quickly returns to its original position once the gust has passed.

The camera movements that are causing the problem seem to be slow, steady ones that typically take several hours to move the camera through an angle of about about 0.2 degrees.

Simon

[PC Paul]

You need it accurate to 0.2 degrees?

Have to say I'd probably back out the zoom a little to keep the target area in sight over the whole range if it's that fussy. Or even do that but get a higher resolution CCD so you get the same effective resolution.

Or move closer to Lundy lol.

[Rick]

Does the camera move back again ?

For this tiny ammount of movment that has a big effect you could be chasing it for weeks. Id look at moving the box neerer to one of the steel uptights holding the barn up, and bolting onto that.

Rick