Safe dry fire mirror array

howe0001

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Aug 13, 2014
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Question:

I've set up a couple of mirrors in my home (basement) that allow me to lay prone, using a rifle scope, look through the 1st mirror (which is aligned with a 2nd mirror), through the 2nd mirror (which is aligned to a scaled target {simulating a 1000 yard target} 85 yards away). This allows my rifle to be pointed at a safe wall in the basement (towards earth under my parking garage) and allows my target to be at the furthest point on my property (85 yards). This is safer from the perspective of nay-sayers rather than just practicing while pointing an unloaded rifle at a neighbors house.

However, the parallax/focus does not seem to adjust properly and I can never get a good focus on the target. I've cleaned the mirrors, cleaned the glass on the door, tried it with the door open (double pane glass). If I simply aim at the target directly (door open or closed - with double paned glass or without), I am able to get a good parallax adjustment and focus on the target. I can even MIL the target and apply the formula and get the range (simulated 1000yds). To me this means the scope, target scale, parallax are all correct just looking through clean air without the mirrors. What would cause this problem with focus/parallax? imperfections in the mirrors? Are the mirrors causing too much refraction?

Anyway, this is certainly not a life changing piece of information if I never find out, but was wondering if larger mirrors would fix the issue. I have a theory that the 6" round mirrors are too small and causing too much refraction. Changing the focal point maybe (similarly to an IOTA/DFAT/IDTS lens).
Maybe I'm the only person in the world curious about this. But was hoping a physicist or other smart person could tell me why my setup does not work well.

Thanks

P.S. I'm familiar with all the DFAT,IDTS,IOTA lens, so not looking for an alternate solution in lieu of an answer to the question. I would sincerely like to get an answer to my above question just for the sake of understanding the physics.

Thanks again.

Tried mirror array with Arken ssh4 and Vortex Diamondback and SWFA - same results.
 
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ma smith

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  • Sep 29, 2020
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    First, kudos on a clever idea. This is an interesting OP.

    With respect to the problem at hand, this is the first check I'd do:

    Are your mirrors dead flat to start, are the frames dead flat,
    and is they are flat lying flat, is the stiffness high enough
    ie, to avoid flex-forming 'lenses' out of the mirror array?
     
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    howe0001

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    Aug 13, 2014
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    First, kudos on a clever idea. This is an interesting OP.

    With respect to the problem at hand, this is the first check I'd do:

    Are your mirrors dead flat to start, are the frames dead flat,
    and is they are flat lying flat, is the stiffness high enough
    ie, to avoid flex-forming 'lenses' out of the mirror array?
    These are by no means expensive mirrors, but they are flat. I 3d printed frame/mounts for them. See pictures.
    20220617_120537.jpg


    20220617_120551.jpg
     

    theLBC

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  • Jun 21, 2019
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    i am going to guess that the focus distance to the mirror is too close.
     

    DannG

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    Dec 5, 2021
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    Cool idea.
    Thinking out loud here, have you adjusted parallax for the distance to the mirror, not the reflection ?
     

    KnowNothing256

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  • Jan 9, 2020
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    Parallax setting should be for line-of-sight to the scaled target, including all the bounces from the mirrors; sounds like that’s probably 85-100 yards.

    I expect this is a mirror quality issue rather than a parallax problem. OP, try just a single mirror to see if the image looks better; poor image quality will be cumulative if the mirrors are the problem.
     
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    howe0001

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    Aug 13, 2014
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    Parallax setting should be for line-of-sight to the scaled target, including all the bounces from the mirrors; sounds like that’s probably 85-100 yards.

    I expect this is a mirror quality issue rather than a parallax problem. OP, try just a single mirror to see if the image looks better; poor image quality will be cumulative if the mirrors are the problem.
    You are correct. single mirror is acceptable quality. Wish I thought to test for that....forrest for the trees I guess. So sounds like I need two quality mirrors. I knew there would be someone here to help. Thanks for the replies. At least I have a direction to march in to make this work better.