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Probably OT: Tree Finder

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  • Probably OT: Tree Finder

    There may be some maching content in here somewhere.

    My house has a view of distant mountains. In between is the enemy of views -- trees. After many years, a few of them are now on my kill list.

    The problem is how to find them They are 400 to 600 yards from the house, on rough ground, and probably 80 to 100 feet tall. They are way too big to shake, and there's no hope of finding them by walking a compass bearing.

    The only solution I can think of (short of artillery) is to wait for twilight, paint them with a powerful light located on a tripod at the house, then stumble around in the woods after dark, find the illuminated tree, and mark it for attention later.

    One of the many "million candlepower" spotlights would probably put out enough light to do the job, but none of them have focusable beams, so they would probably be useless for identifying a single (though large) tree at that range.

    Anyone know how to build a simple collimator for such a spotlight?

    Anyone have a better idea of how to ID those trees?

    Thx, J

  • #2
    Laser pointer and scope?


    • #3

      Don't think I could see a laser pointer from the ground. Remember, the illuminated part of the tree will be 80 to 100 feet off the ground. I'll be on the ground looking up, trying to see the light beam through the foliage from as much as a couple hundred feet away.


      • #4
        Another approach (borrowed from Special Forces) would be to have one or more "operatives" stationed in the woods somewhat closer to the target area, in radio communication with the fire-control base (your house, with you stationed at the viewing location) and have them "designate" various nearby trees one at a time, either by means of a handheld spotlight or perhaps a green astronomical laser pointer, such that presumably if you can tell an operative "yes, that's one of them" by coded radio transmission, then they will be in a good position to either more permanently mark the tree(s) in question, or else gather GPS coordinates and close-up reconnaissance photos to help the tree extraction team do its thing later on.


        • #5
          While fairly simple, this idea would take a bit of time. Long ago I made up a round frame with a lip around it, and stretched some space blanket over it. Glued all around the edges to make it airtight. Then through a suitably placed tube I could create some suction behind it. That pulled the space blanket into a pretty good concave. If you mounted three arms on that, coming to a point, then mounted a single halogen bulb at that point, you could focus it by varying the suction. It won't be optically perfect, but you'll get a not too shabby beam out of it. The longer the arms, the shallower the concave would have to be, and the better the performance. Definitely need a tripod or some adjustable mounting method so you can point it properly.

          Another idea- put a diode in series with the ac supply to the bulb. That will drop the output, but it will also make the bulb output a stronger 60 hz signal. Once it's pointed at the tree, you can use a listening device to detect the reflected 60 hz signal. For a listening device, a solar cell can be the pickup. You may or may not need an amplifier between the cell and the headphones, but it's possible that sensitive headphones would be able to pick up the reflected light from the tree.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


          • #6
            Hmm ... this is making me think. How about a car headlight powered by a battery charger, collimated (sort of) with a fresnel lens. Problem is, I don't know diddly about optics & wouldn't know what lens specs to look for.


            • #7
              Have your "Scout" with radio bring alone a helium filled baloon with a string attached on a calm day. You see the balloon in front of a tree you want gone tell him to "X" it with spraypaint. Just a thought.


              • #8
                Clear cut them all?
                Errol Groff

                New England Model Engineering Society

                YouTube channel:


                • #9

                  Now that's a bright idea! Only problem is getting the balloon down again once it's up -- we're talking about deep, dark, thick, Walt Disney spooky forest. But balloons are cheap. I could use a half dozen and just let them go if I can't get them down. And it would work in daylight -- big advantage.


                  • #10
                    Well, you can buy a fresnel lens that's 8-1/2 x 11 in a dollar store. It's usually called a magnifying sheet. You could stretch it across a frame to keep it flat. Or you could check thrift stores to find a magnifying screen designed to sit in front of small tvs. You'll have a lot better luck with that than the magnifying sheet. In any event, the best results will be obtained by using something close to a point source of light, hence my suggestion to use a halogen bulb. A car headlight bulb will work fine- the bulb itself that is. The best result you'll get is a nicely focused image of the filament itself on the 'target'.

                    It might be a stretch to say you can plant a circle of light on a tree 600 yds away though. You might find that even with the best focusing, your spot would still be quite broad. You might have to make good use of twilight or darkness.
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                    • #11
                      WTFPIC* Use an industrial laser. Just burn the tree off at the height you wish!

                      *With Tongue Firmly Planted In Cheek


                      • #12
                        If the trees were closer, the top could easily be shot off with a high power rifle.

                        That has been done here with very large branches that were overhanging dangerously.

                        BUT,, this wasn;t done at 600 yards.


                        • #13

                          No one's going to shoot the top off these suckers with anything short of artillery.

                          So far, the spotter, balloon & chainsaw method is in the lead. :-)


                          • #14
                            If you are in the West, you could simply wait for beetles, or a forest fire to destroy all the trees. We're going to start missing them around here!


                            • #15
                              I can think of a few things, including;

                              Take that million power light to the tree, and illuminate it from below. On a dark night the tree will light up well. The spotter with a cell phone can then direct you left , right, etc.

                              An interesting spot beam can be made with a 3 watt minimag light and an older C or D cell maglight. Take the head off both of them. Insert the minimag into the head of the D cell light. move in/out till it's focused.

                              Here's one I made with a delrin adapter.

                              Twenty feet down the hall;

                              and a tree 300 feet from my house, first in ambient light and then with the turbo minimag

                              At the end of the project, there is a profound difference between spare parts and extra parts.