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Shooting Lens-Where to have focal point ground?

Discussion in 'Shooting Related Threads' started by DocJim, Mar 26, 2010.

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  1. DocJim

    DocJim Member

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    A visit to my eye doctor yesterday revealed I'm not seeing as well as I used to which prompted the following questions. Corrective lenses are usually "ground" so the clearest area (focal point) is in the center of the lens. Shooters rarely look straight ahead and with the help of another I find that I look 20 mm to the left and 10 mm high from RIGHT lens center (about a 25 degree elevation from the horizontal). I patch the left eye so that's not a consideration. Should I have my new right lens (I'm right eye & right shoulder)ground with the focal point at that area to maximize clarity? (Assuming it can be done).................AJ
     
  2. crusha

    crusha TS Member

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    You think right. It should be high. Mount your gun and mark the spot.
     
  3. W.P.T.

    W.P.T. TS Member

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    I had one Eye Doctor many years ago have me mount a gun in his office so he could mark the Optical Centers and where they should be on the lenses ... Take your gun with you and mount it for him to do the same, keep it in the case until you and the Doc are in the room so he can get it right and you don't freak out any of the other patients in the waiting room ... WPT ... (YAC) ...
     
  4. JLSO5

    JLSO5 Member

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    Do the Decots, Rangers, Hi-Def people of the world take this into consideration when they make RX glasses? I know my everyday glasses are centered as the lens were marked by the optician. I just assumed the shooting lens people took that into consideration.
     
  5. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    JLSO5, unless they know how you mount the gun, there's no way for them to know that! Clarence Willis of Baltimore,Ohio is man I use to have my lens made. He known the importance of getting the optical centers just right for you! Most others don't pay much attention to that small detail!

    Hap
     
  6. DocJim

    DocJim Member

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    JLSO5: Don't know. I would think that the way each individual looks down a barrel would be a little bit different. Maybe not enough to be significant if you have good visual acuity but maybe it's significant when the vision starts to get marginal. I would imagine that the lens manufacturers probably make a "one size fits all" lens unless specifically requested. Certainly as your gaze moves away from the "sweet spot" of your lens the object will appear less sharp; I can see that with my "everyday" glasses. Maybe eye & glasses specialists will jump in here...........................AJ
     
  7. maltzahn

    maltzahn Active Member

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    I have both, make Rx lenses for the BA shooting frames and have the 4th largest optical lab in the nation, in the family.

    A shooting frame raises the optic centers higher, positioning the sweet or clarity spot for looking down a shotgun rib. The only place we see clearly in Rx lens, is the center of the ground prisms or center of the optic. You can move your street glasses around on your face to prove the optic center and to notice how large the sweet spot is related to the stength of correction.

    The optician measures the PD (pupil distance) with a mm ruler or a digital box the looks like a small field binocular. The measure is each eyes pupil distance from the center of your nose. That is even for about 50% and off one side or the other 1 to 4 mm on the other 50%. This is the number the lab places the optic centers on for each lens. So...now we have the lateral center and the frame will set the vertical center.

    Offsetting or d-centering the optic for shooting is done for a few that request it. It should be measured and will end up 3 to 6mm left for a righthand shooter. Visa versa for a lefty. The end product will be a set of shooting glasses that offers a bit more clarity based on looking throught the optic more to center while on the stock. The disadvantage is not looking through the optic center while using the glasses for other than shooting. D-centering is not for the guy that puts on his shooting glasses and wears them all day. Not only will the optic make you feel uncomfortable, but your eyes inhently try to see clearly all of the time open. The eye muscles will stain trying to correct looking through the edge of the optic. The shooter ends up with a set of glasses that can only be used on the line in a stronger prescription, and uncomfortable in a lighter Rx.

    Beware of what your asking for and realize the results of gaining the request.


    Maltzie
     
  8. JLSO5

    JLSO5 Member

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    Thank you for that info.
     
  9. Unknown1

    Unknown1 Well-Known Member

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    <blockquote><I>Do the Decots, Rangers, Hi-Def people of the world take this into consideration when they make RX glasses? I know my everyday glasses are centered as the lens were marked by the optician. I just assumed the shooting lens people took that into consideration.</I></blockquote>

    That's one reason why you want to buy shooting glasses from someone you can sit down in front of instead of someone who does business by mail, long distance, no matter who they are.

    MK
     
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