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Thread: Fixed Parallax @ 35 yard Scopes?

  1. #1
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    Fixed Parallax @ 35 yard Scopes?

    Hi

    I've always had adjustable parallax scopes but am thinking of going for a fixed one to possibly save faffing about when I'm in a hurry for a shot on a squizzer.

    How do they work? Is everything crystal clear up to to 35 yards and beyond that blurry or is everything blurry except anything at 35 yards?

    Cheers for any replies!

  2. #2
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    My 35 yard parallaxed scope tends to be blurry at extreme close range, sorta unusable at under 5, acceptable at about 8 yards, pretty decent at 15, then increasingly clear up to 35, then after that, almost as clear out to Fort Mudge and beyond.

    There's some houses 1/4 mile away across a field from my place, and even those are in pretty good focus.
    However, my eyes are young eyes, so mine can do a lot of extra focusing work that older eyes might not be able to.

  3. #3
    Gary C Guest
    What faff will you save?

    Fixed PA will be either pa at 100 - which will usually be blurred below 20, or fixed at airgun ranges which mean blurred further out.

    You are far better in your case having a front PA scope and leaving it PA at 25 yards for the squirrels, if you don't touch it the PA is fixed

    You have always the option then of bringing it in for rats and out for stalking / observation.

    We marketed a scope exactly for this purpose, the Cobra. This is being discontinued due to the popular demand for side P/A

  4. #4
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    Gary

    How does that square with the Meopta 7x50 and Leup 3-9x40 on my desk both of which are fixed at 100 yards.

    Both appear to be crystal clear from about 7 yards to infinity?

    Richard

  5. #5
    Gary C Guest
    Hi Richard

    A x7 will have a huge dof. I'd doubt that the Leup on x9 is clear to 7 yards.

  6. #6
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    Quote Originally Posted by Gary C View Post
    Hi Richard

    A x7 will have a huge dof. I'd doubt that the Leup on x9 is clear to 7 yards.
    Ah I didnt actually look at the zoom ring.

    7 yards is the gunroom to the bedroom window.

    The Meopta as before has the windowframe and ret in pin sharp focus.

    The Leup has both pin sharp at 6.5x (as marked) above that the ret is still sharp but the windowframe gets progressively more fuzzy.

    Thats something I've never noticed before, however given they were both on centrefires thats not surprising

    Every day is a schoolday.

    Richard

  7. #7
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    "You are far better in your case having a front PA scope and leaving it PA at 25 yards for the squirrels, if you don't touch it the PA is fixed "

    Thanks, that does make sense!

    I spent the weekend fiddling with a new scope, messing about with parallax, magnification, focussing ring, illumination and got a bit exasperated with it all - started dreaming of just looking through a scope and shooting something!

  8. #8
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    Mine seems to be fine, except for really close distances.

    However, when i soom mine in the x9 mag, it seems to blur in the middle

    But thats probably 'cos it was a fairly cheap one
    CZ Silhouette 16" .22lr, Nikko Stirling 4-12 x 50 Scope
    S200 .22, one piece stock, 3-9 x 50 scope
    BSA meteor .22, an antique

  9. #9
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    This is not so simple as it first appears.

    Some 'scopes have excellent depth of focus, i.e. what the previous posters mean when they talk about "parallax" but which actually describes the ability to maintain both near and far objects tolerably well focussed.

    This is a useful quality, however such a 'scope will still suffer more or less severe parallax errors whilst still giving a sharp image. Unless the distant image and the crosshairs are in EXACTLY the same focal plane, then small off-centre movements of the eye will result in the crosshairs apparently moving compared with the target image. This utterly destroys any accuracy potential, unless the shooter can place his eye exactly in the optical centre of the light path from the eyepiece, every time

    It is quite easy to make a 'scope which appears to have a great depth of field, by using simple tricks like inserting a small aperture inside the tube, a bit like stopping down a camera lens. It also sharpens up the image, but it also cuts out a lot of light, which will not be noticed in good daylight.

    More honest 'scopes acknowlege such trickery and simply use small objective lenses and lowish magnification to give enormous depth of focus, e.g. 1.5-5x20 or 2-7x32 designs. They are also usually much better quality for the same price, but seemingly undesirable compared with bigger 44 and 50mm objective 'scopes using cheaper glass and coatings to no benefit.

    You can buy "focus free" binoculars which use the same tricks, but as anyone who has used a good pair of e.g. 7x50 binoculars will agree, they actually have pretty limited depth of focus and have to be adjusted at almost every range, even well beyond 100 yards. The larger the objective lens, for a given magnification, the smaller the depth of focus, unless "stopping down" tricks are used which negate the light gathering benefits of the large objective. Basic laws of physics.

    So to summarise:

    For good depth of focus, choose small objectives and low magnification, but realise that true parallax error will be substantial, when used at anything other than the "parallaxed" range

    For accuracy, choose larger objectives and higher magnification with an adjustable objective, and accept the need to re-focus the objective to suit the range and so eliminate parallax error.

    For true simplicity, accuracy and optical quality, choose a fixed mag. fixed focus 'scope e.g. 6x40 or 7x50, parallaxed at your usual range, e.g. 30 yards for airguns, 100 plus for centrefire. Zoom and PA adjustments will always move the zero, by how much and how repeatably depends on the precision, tolerances and cost of the mechanisms involved. Zoom mechs. require extra lenses which must degrade quality and/or increase price.

    How many zoom'scopes end up just being used at one magnification every time ?

  10. #10
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    Quote Originally Posted by supersonic View Post
    How many zoom'scopes end up just being used at one magnification every time ?
    Interesting point.
    I tend to use my 3-9x40 at 4x, although I have used 3, 6 and 9 depending on exactly what I'm trying to do.

    I decided to give up on my fixed PX scope, because usually I shoot at between 10 and 20 yards in my garden - not good for the 35 yard PX - so I ordered myself one of the JSR 3-9x40 PX IR scopes to replace it.

    Does everything my old scope did better - then does a load more on top, all for a decent price.
    Perfect - very eager to see it arrive.

  11. #11
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    Thanks for the thoughtful replies ...

    I can see it's easy to get a bit carried away with all the bells and whistles of modern scopes, which can be fun , but sometimes it's best to keep it simple.

    I may have a look at some low mag fixed scopes just for hunting and keep the big adjustables for fun.

  12. #12
    Garry is offline I scrolled the page up too fast and it fell off
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    Quote Originally Posted by supersonic View Post
    For true simplicity, accuracy and optical quality, choose a fixed mag. fixed focus 'scope e.g. 6x40 or 7x50, parallaxed at your usual range, e.g. 30 yards for airguns, 100 plus for centrefire.
    Would the JSR 6 x 32 PX Mini fulfill this criteria?

    Am I right in thinking that a scope set for px at 30 yards would be aimed higher or lower via milldots at other distances? Or would the px have to be set again?

    I understand that a scope hitting bullseyes at 30 yards means aiming higher or lower at other distances, but I don't understand how a px control comes into it.

    My limited experience only involves using open sights as a frame of reference for this subject.

    Thanks
    Garry

  13. #13
    Garry is offline I scrolled the page up too fast and it fell off
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    Quick bump for the above questions, ta.

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