Interesting read if you have a minute or two.

Discussion in 'General Airgun Chat' started by Steve, Oct 20, 2014.

  1. Steve

    Steve Member

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  2. daveuk

    daveuk New Member

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    I started reading it but - whether it was the time of night, or because the scopes were based on a minimum price of $1500, or because of the sheer amount of content - I gave up. Sorry but for me it was not interesting.
     
  3. craigtodd1968

    craigtodd1968 Member

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    What was interesting was where the march came.
     
  4. Tone

    Tone Active Member

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    As a bit of a scope tart I did find this interesting to have a quick scan through, the tests look well thought out and comprehensive.

    For me the reticle choice is very important and it was interesting to see how the lead table changed when this was applied.
     
  5. RobF

    RobF Administrator Staff Member

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    Was considering they were testing a 42mm scope against a 56mm and saying the field of view was tight... :eek:o

    And that they were working on a 5-50x56... (sept 2014 date)... It's only been out 2 years.

    Dunno. Its interesting to see comparisons but I'm not wholly convinced when someone says the mag is the limiting factor and doesn't mention it's a made up number... it's like using the wheelbase of a car to select a test range.

    There's a test for visual resolution and it doesn't involve using your eyes. You use kit because eyes aren't very good testers.

    But the mechanical tests are interesting, and it's really interesting to see how almost as many shooters think things like rets and turrets are as important as optics. Which goes to show why we probably have the scopes we do out there and why we don't have the scopes we want or should need.

    It probably shows why things like chairgun don't work as well... but it'd prefer to see how well a scope tracked not how well 20mils dialled exactly measured 20mils on paper. The March is punished for this, but if you read the breakdown it returns to zero as well as anything else, and suffers with the elevation adjustment range a bit and it's cant is as good as the top scope.

    I'm not saying it's perfect, but marking it down so low because 1 click doesn't precisely match what it should be, yet it still actually tracks ok seems a bit harsh. All i want to know is that 55 yd's is dialled 4.0 each time. I don't care what 4.0 is compared to a measurement of 4.0 moa on a ruler. I just want it to go from 0 to 4 and back 1000's of times the same amount.

    I guess it could be because a lot of shooters shoot by the numbers and ballistic programs unlike us which rely on shooting.
     
  6. holly

    holly Well-Known Member

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    Scope

    There is an old Spotting scope down the club , cannot remember the name . they were advertised in the shooting press for £ 60 . it is i think 60 mag with what looks like a 60 mil objective lens . it is dirty , battered , the objective lens has a big chip out of the side of it . but it is bright , snaps in and out very well . taken into the wood it is brighter than my lupe is on 40 mag . i do believe that as shooters we are getting the shite end of the stick . never been a fan of chair gun . why would you want to work out what your rifle does on a computer . when you can shoot your rifle to do it and at the same time , practice your windage and just enjoy shooting . ??? HOLLY:)
     
  7. RobF

    RobF Administrator Staff Member

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    probably because a spotting scope has a huge objective hols... measure it, what's yours?... A spotter lets in a lot more light.

    A 56mm scope has twice the lens area almost of a 40mm scope to let in more light. An 80 has twice as much as a 56.

    It's also a fixed mag, so has around 4-5 less lenses. With each lens losing say even 1% a fixed mag will lose around 10% in transmission

    but a zoom has another say 4-5 lenses so loses another 5%

    And that's assuming 1% is correct, and that's assuming that the 1% stated is across the whole visible spectrum as well, which is probably not correct.
     
  8. holly

    holly Well-Known Member

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    Down

    I was down the club trying to get my Old GC2 to shoot propperly ( nope ) the spotting scope is called a greenkat . actually when i looked at it properly it is 60 mil objective lens with a 22 mag rear lens . i tried it at 52 yards and 55 . and there is no way on this planet that anybody could mistake the two ranges . front parralax by the way . if this can do this on 22 mag , why would we need a varible mag scope . we are getting ripped off scope wise with shooters paying two and three thousand pounds nowadays for a scope . ??? HOLLY

    PS although it is 60 mil most of the way down the scope . it does not weigh any more than a big nikko . i just wished i was able to make some 60 mil scope mounts and stick it on a rifle . side mounted rear lens and all . just to see what would happen .:D
     
  9. LAity

    LAity Goed Geschoten

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    Loved it . I have a few Nightforce's myself and really now want the "Beast" !!!!! Right now :)

    LAity
     
  10. Dave Ramshead

    Dave Ramshead England HFT Team squatter

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    Loved my nightforce as well, mega scope.
     
  11. holly

    holly Well-Known Member

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    Thinking .

    Thinking about the spotting scope and thinking of way's to fit one to a rifle ( nope ) it got me thinking about the side mounted rear lens . we have off set triggers , why not off set rear lens .the benifit being that the head would not be twisted around , no tension on the neck which you can get if in the aim for a while . you might be able to just twist the cheek piece around to the right , to bring your eye in lane with it . be good for spectacle wearers as well . looking through the middle of the glasses . ??? HOLLY:)
     
  12. cloverleaf

    cloverleaf Active Member

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    Personally I thought the link was an excellent read with generally well-thought-out testing procedures.. the tester evidently spent a hell of a lot of time conducting and writing the tests up so hats of to his commitment and to Steve for posting the link :)

    Rob, I think you'll find that objective diameter has no effect on a 'scopes FOV; being analagous to an aperture in a camera lens - i.e. FOV is constant but light transmission and depth of field change with varying aperture / objective lens diameter.

    Looking at the FOV values for the 'scopes of same mag but varying objective diamter on the Hawke website supports this idea.



    I think your last sentence pretty much hits the nail on the head. Ultimately, while these 'scopes are of specifications that largely suit the needs of air-rifle users, they're designed to be used by centrefire shooters who have requirements that differ somewhat from those wishing to use the glass on an airgun.

    For example, the mag range might not be important to the FT or HFT shooter as the 'scope will most likely always be set to a single (possibly highest) mag setting. Conversely; someone shooting a .338 over ranges between 100 and 1000yds would probably very much appreciate a wider mag range from which to choose.

    Similarly, as you say the correlation between stated and actual turrent adjustment increments may be of little relevance to us as we tend to arrive at hold over / hold under values empirically through testing. We can do this because pellets are cheap compared to centrefire rounds, while we choose to do this since, as you say, ballistics programs are limited for airguns and accurate ballistics information is much more freely available for firearms. Hence, it's a much more plausible and viable proposition for long-range centrefire shooters to use ballistics tables / software to ascertain correct POA at range.

    I agree about repeatability though; a feature that's definitely important to everyone and an example of where the requirements of different users converge..
     
  13. RobF

    RobF Administrator Staff Member

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    Yes, sorry... FOV isn't to do with objective. You're correct. From the March's i've looked through they are tight because of their focal length, something that isn't published... but leads to better range finding... (in my opinion), because the longer focal length gives a shallower depth of field. But it also makes for a narrower field of view.

    Talking to one company last year, they said their marketing dept had said their customers like the bright wide field of view so they could find targets easily. My comment was if their natural point of aim was half decent they'd be looking at it when they looked through the scope. They were a little taken aback to hear that some just got on with fixed 32-40-45x scopes... :D
     
  14. cloverleaf

    cloverleaf Active Member

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    Cheers Rob - tbh I'm still learning about optics as they're not my strong point :eek:

    In my quest to better understand I've found a couple of interesting sites - there's this calculator which is useful for understanding about the relationship between the focal lengths of telescopes, their eyepieces and resultant FOV and magnification.

    The wikipedia page on telescopic sights also gives a decent overview of the relationship between the optical parameters involved in a 'scope. It's interesting to note that eye relief is apparently dependent on focal length (which I didn't know before I read the page).

    I think your point about high mag 'scopes raises two interesting points - a) again the different requirements of different user groups, and unfortunately b) that potentially marketing men are happy giving uninformed customers what they want rather than what everyone might actually need..

    In other news I appreciate your Reznor / Cash reference :)
     

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