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Thread: New Way to Make a Focus Panel?

  1. #1

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    Jun 2009
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    New Way to Make a Focus Panel?

    Okay folks... we have GG and parafin sandiches and combinations with fresnels. The parafin variety seems to be very popular making for better viewing but the parafin melts easily. Has anyone tried a hot glue sandwich?? Sort of an emulation of the parafin version.

    1. Make a bubble-free ball of white-ish hot glue and center it on the bottom glass (low temp hot plate slowly brought up to temp?)

    2. Slowly heat the glass to begin the melt process.

    3. Center the top glass and work it gently to mash the melting glue evenly between the sheets working it gently outward toward the edges and ensuring no bubbles form.

    4. Continue working the glue outward until it bleeds past the edges of the glass and forms a thin uniform layer of glue.

    5. Use calipers on all edges/corners to ensure even distribution of glue and adjust accordingly by lightly squeezing.

    6. Remove from heat and let slowly cool on a thick towel.

    7. Use razer blades to trim the excess from the edges and remove any spill over on the exterior surfaces.

    Worth a try?? It would certainly be less prone to heat problems.

  2. #2

    Join Date
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    Re: New Way to Make a Focus Panel?

    Please let us know how it works out!

  3. #3

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    Re: New Way to Make a Focus Panel?

    I'll need to buy a bigger stand-alone stove burner and a thick sheet of very flat iron... might need to have it machined to absolute flatness. Then I may give this a try. OR... maybe I'll try the milky epoxy method outlined in my other thread.

  4. #4

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    Re: New Way to Make a Focus Panel?

    I just made one with a sheet of waxed paper in front of a fresnel - it seems to work fine.

  5. #5

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    Re: New Way to Make a Focus Panel?

    How about drymount sheets? They are thin and flat already.

    Hot glue is pretty viscous and thin glass is flexible so I think you would have issues getting a thin even layer. But give it a try.

    Making ground glass is pretty much the easiest option - that is why it is most commonly used.

    A fresnel is "better" if you want maximum light gathering.

    I don't see what would be gained with a bit of hot glue which would be more difficult than gg and would transmit less light.

  6. #6

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    Re: New Way to Make a Focus Panel?

    If you're wanting to make your own the easy way, get a can of NoVue window spray at the paint or hardware store. A few very, very light coats and you have a ground glass. Not the best you'll find, but it works. There are auction sellers who have ground glass. I would rather just buy one and be done with it. That happens when you get old.

  7. #7

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    Re: New Way to Make a Focus Panel?

    I'm trying to emulate/simulate the Boss screen but eliminate the worry of melting the parafin. I live in south Texas.

  8. #8

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    Re: New Way to Make a Focus Panel?

    Why emulate the BOS? It would seem that having the focus plane offset from the front of the glass would require reworking whatever is holding the glass so it would be at proper focal distance. The ideal is to have a focal surface as thin as possible which will drop in so it is positioned exactly where the front face of the existing ground glass is. There are ways to accomodate this by milling or making the front cover sheet of glass smaller so that only the rear sheet contacts the frame, but why bother?

    There are also self-adhesive window films which could be used. Or perhaps break open an old laptop display and grab the diffusion sheets and/or fresnels out of it and see if they would work for you.

    I just think you are going to have trouble making a thin layer of some translucent liquid and getting it positioned correctly.

  9. #9

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    Re: New Way to Make a Focus Panel?

    Regarding a diffusion sheet: Intriguing but how would I adhere it to the front of the glass permanently, evenly, with no trapped bubbles, and without compromising its translucence?

  10. #10

    Join Date
    Oct 2009
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    Re: New Way to Make a Focus Panel?

    You were going to sandwich the glue, just sandwich the diffusion sheet. Or get the self-adhesive type of sheet and put it on the front side using some care it is not difficult to avoid bubbles. If you get a bubble you can move it to the side or worst case, pop it with a needle. Or use any sort of thin slow-drying adhesive.

    Pop open an old film holder, cut out the back and slip a sheet of the diffusion material where the film should go. Remove the ground glass entirely and pop in your portable focus screen. That way you can experiment with different things or have a wide fresnel and a long fresnel. Your darkslide will protect the GG when not in use.

    There are tons of possibilities and experiments to be done.

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