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Chronograph Diffusers

Discussion in 'Handloading and Reloading' started by cm250, Oct 27, 2009.

  1. cm250

    cm250 New Member

    Sep 2, 2009
    North texas
    Hey all, just sent a money order off for a used Chrony F1 today, only thing wrong with it is that it's missing one diffuser. Was wondering if these have to be bought from Chrony or can you make your own. From what I have read they are just to reduce sunlight effects on a bright day. Have seen pics of other people's chronographs that look like they have home made diffusers on them. Was thinking about cutting a couple out of a white plastic 5 gallon bucket and adapting post/upright mounts to them.
    What do you think, would that work?
    Thanks for any info!
  2. MCMXI

    MCMXI Mentor

    Jul 1, 2008
    NW Montana
    cm250, as I mentioned in the other thread, chrono sensors need contrast between the bullet and the background. My Chrony Beta Master manual suggests marking bullets with a black pen if the chronograph is showing Err1 or Err2 readings. The background should be as uniform in color/contrast as possible. An overcast sky, if light enough, is uniform. A solid white, non-translucent plastic is uniform and bright enough if there's sufficient ambient light. With solid screens, you may have an issue once the sun gets low in the sky or if you position the chrono under an awning or some other form of shade that reduces ambient light. So in summary, it's all about contrast between the bullet and the background. High contrast = good, low contrast = bad.

    I made aluminum screens for my chronograph but the local range has an awning that casts a big shadow after about 2pm. The chronograph works great in bright sun but not so great as the ambient light decreases. I plan on modifying the screens to account for this.

  3. mongoose33

    mongoose33 Active Member

    Jan 2, 2009
    This is related to your issue--I have a chronograph I wanted to use indoors. If the light is from fluorescent lights, it'll screw up the sensors.

    So I use a piece of tagboard/foamboard on top of the posts, and shine incandescent 100-watt bulbs in clamplights up at them. Works great:


    Sorry about the bad cellphone pic.

    If it's cloudy, you probably don't need diffusers; since what I'm using in the pic above works, anything that creates a translucent background should work fine so long as there's enough light. The point of the above pic is that you could even have a fairly large piece of translucent plastic--perhaps the side of a barrel or something--on top and it should work fine.

    And if you want to use it at an indoor range, just duplicate the above.
  4. Ol` Joe

    Ol` Joe Senior Member

    Feb 25, 2004
    The defusers actually give a brighter background for the sensors then a clear blue sky. A white clouded day is actually brighter to the sensors then the darker "blue" sky.
    Shooting chrony sells the rods and defusers (don`t ask how I know) and they are easy enough to make at home if one wants. I`d go with a wood dowel in place of a metal rod if you do make your own, they likely won`t be as hard on the plastic housing if hit by a stray bullet.
  5. bullseye308

    bullseye308 Participating Member

    Nov 24, 2007
    Smyrna Tennessee
    I'd definitely replace the metal rods with wooden dowels. "If" you hit it, you won't damage your chronograph. At least that is what I hear. :uhoh:
  6. ants

    ants Senior Member

    Nov 24, 2007
    Wooden dowels and white milk jugs (some 5 gal buckets may be too dense to let enough light through from above). White milk jugs are free and work great.
  7. Sport45

    Sport45 Senior Member

    Mar 5, 2004
    Houston, TX
    I thought about buying that chronograph myself. Looked like a pretty good deal.

    If I had bought it, I was thinking I could buy one of those translucent 24" x 48" fluorescent light diffusers at Home Depot and make diffusers for both sensors for about $3.

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