Refocus after range finding?

Discussion in 'Tips, tricks and tutorials' started by dhb, Oct 18, 2012.

  1. dhb

    dhb Canadian FT Novice

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    I'm setting up my new Falcon T50 and have a question about focusing before shooting. I understand that it's most precise to range find at high magnification. If after I range find, I turn the maginification down to shoot, the target goes slightly out of focus. Does everyone (well, the good shooters) refocus on the target prior to taking the shot?
     
  2. Neil-T

    Neil-T Boingers forever.

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    If you originally focused and range found the target on full magnification, and have dialled your clicks in to hit the target at the original distance on full mag, it will make little difference what you mag down to, but IMO you need to see the target clearly, so yes I would turn the side focus wheel so you can see the target clearly, but don't change the clicks from the original setting. Neil.
     
  3. Conor

    Conor Never been banned from sales Staff Member

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    Is your occular correctly set up, ie are the cross hairs in sharp contrast with the a pale background
     
  4. dhb

    dhb Canadian FT Novice

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    Yes. Apparently the focus shift is the result of the reticle being in the second focal plane.
     
  5. nemesis

    nemesis 55yrd standing expert, or was it 8 or 9?

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    The ret being in the second focal plain should not make any difference,if you are having problems you describe I would of thought the same as what Connor has told you,that you haven't got the diopter setting correct for your eyesight on the ocular lens,a friend of mine once had this problem on a sightron,it turned out to be the diopter not set correctly.
    Turn it down to ten mag then adjust the ocular lens,then turn it to fifty mag and see if the ret is still
    clear.
    If it's still doing it then I would suspect the scope.to be faulty.You should not have to re-adjust the focus every time you turn the magnification down.
     
    Last edited: Oct 19, 2012
  6. bjp

    bjp New Member

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    Hmmmm, excellent question as I have the same scope and was wondering the same thing. I have set the "fast focus" ring so that the reticle is as cleaar as my tired old eyes can see.

    As an aside dhb, have you dropped the scope or subjected it to a good whack of late?
     
  7. DeanB

    DeanB Member

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    Hi Neil,
    The original question implies that the scope will not range the same irrespective of the magnification. I know that applies to some Big Nikkos. From your response, I guess that is not the case with top end scopes.

    It may be that the scope ranges well at full mag and the zero doesn't shift when the mag is changed so perhaps he should just change the mag to shoot.

    Dean
     
  8. neilL

    neilL New Member

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    Just one other thought. If the turrets are wound some distance from the optical centre then the image quality will degrade at low mags (shadow or softening on one side for example).
    The other possibility is that as you drop the mag there are likely to be several objects in the field of view at different distances to the target and the eye can easily be distracted and focus on something else.

    Cheers
    Neil
     
  9. nemesis

    nemesis 55yrd standing expert, or was it 8 or 9?

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    This is spot on advice,never thought of this,a scope always works best when you go to the trouble of optically centering it.
    All the scopes i've had in the past inc my nikko diamond didn't loose focus when dropping down the magnification.
     
  10. Pod

    Pod New Member

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    The depth of field at 10x compared to 50x should be huge! If its all in focus at 50x you shouldn't be able to detect it being out of focus on 10x.

    I'd suspect a dodgy scope.
     
  11. dozbadthebad

    dozbadthebad BFTA 2010 European Champion & Pooch Plinking Plonk

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    this is happening with my 20 x 50 lup theres no movment in POI just the pa changes when i lower the mag by say 8 yds so on 50 x at 50 yds when i lower to 20 x the pa comes in at say 58 the ret is in foucus at all mags i have no anser also the scope has just come back form leupold from a servis
    ????????????? :eek:o
     
  12. RobF

    RobF Administrator Staff Member

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    Saw this problem on the long range variant prototype of the t50 and I've seen it on a march 80 as well. I'd consider it a fault. Assuming correct eye relief and diopter the focal plane should not shift away from the reticule plane when the magnification is changed. Worth checking you aren't nudging the parallax first though.
     
  13. simona

    simona Active Member

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    I've had 3 IR 10-50 Debens and every one needed a refocus when dropping from 40 mag, my chosen rangefinding power, to 20 x to shoot. This amounted to 4-5 mm on the wheel, which on one of these is about 5 yards at the top end. Both my non- IR 10-50 Debens have a totally different zoom ring design (same as Custom Shop) and stay in perfect focus whatever the mag.

    I did hear that at least one S&B FT needed serious refocusing depending on mag.

    It's not nice to deal with but is only fatal if POI moves too.
     
  14. maestro

    maestro Member

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    You're right, Simon, my first S&B FT had an interesting rangefinding at different magnifications (constant between 42.5-50x, dropped about 3 yds between 40-42.5 then almost constant again down to 35x, I didn't measure further down) but the newer ones keep the focus between 20-50x, at 12.5 there is already a noticeable shift in focus but not too many people shoot at a low mag like this.

    There can be a reason to focus a few yds closer after the precise rangefinding in order to be able to see more from the pellet flight, I personally tried it but didn't apply now because the unsharp image was too annoying.
     
    Last edited: Oct 22, 2012
  15. RobF

    RobF Administrator Staff Member

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    My 60 is crystal all the way through, as is my Deben, and my Walthers, which are the same manufacturer (Hakko) as my Custom shop.

    You got a 20-50 serviced by Leupold Doz? And it came back in one bit!? I thought they were pulling the boosters *** them...(or heard it on the rumour mill)
     
  16. maestro

    maestro Member

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    **

    Please help me to learn, what is that English word which is only 2 characters long but is so very dirty that it has to be **-d out? :)
     
  17. RobF

    RobF Administrator Staff Member

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    I think it was " on " and " off " because they were part of words describing an action. Fixed now.
     
  18. dhb

    dhb Canadian FT Novice

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    Problem resolved

    When I carefully adjusted the occular focus the problem went away - user error. :eek:

    I'm quite pleased with the scope so far. Of course, now that there's a silver version I would prefer that atop my TM-1000...
     
    Last edited: Jul 16, 2013
  19. fudge-1200

    fudge-1200 New Member

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    It could be the scope is faulty, I had one and after a couple of months of use it stopped parallaxing distances over 40 yds, also in the winter the ring that adjusts the mag seized up to the point that it would not move.
     
  20. RobF

    RobF Administrator Staff Member

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    Check the op thread date :)
     

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