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Question about turret backlash |
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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Posted: June/14/2018 at 09:10 |
I understand turret backlash, but still have trouble knowing if a scope's turrets are CW or CCW if they don't have a target knob to see which direction it's moving. If I have to turn the knob CCW and out, I'm moving the turret's screw away from the erector tube and spring. To prevent backlash on an inexpensive scope, it's recommended to go a few more CCW clicks past the intended amount and then come back that amount to finish up pushing against the spring.
If the bullet's POI needs to be moved up, the crosshair needs to be pushed down so when the rifle is elevated for the new crosshair position the poi hits higher. But turning the turret CCW would seem to lift the reticle up instead of down. If this is correct, how does turning it CCW (or out) move the reticle down? Thanks. |
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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Some scopes are CCW, some are CW. I haven't seen a modern scope that has no markings whatsoever. Forget about the erector, look at the markings - and, as Reagan said, "Trust, but verify." For clarity: there is a HUGE difference between an inexpensive scope and a crappy scope. And Leupold is famous for the need to dope beyond then come back to the right change, even their high-end stuff. Maybe they've fixed it, maybe not, I don't care, I don't buy Leupold products.
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GiantGreg
Optics Apprentice Joined: February/22/2018 Status: Offline Points: 68 |
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My best
guess would be that CCW vs CW would be that one is using left hand vs
right hand cut threads. If you want
to crank and accurately get the right angular adjustment, then that comes with
a price. You can put
a spoiler on geo metro, but it won’t make it perform like a F1. |
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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On most of my scopes, CCW for up elevation looks to be turning the turret "screw" out and moving the erector away from the spring. But to move to POI up, it would have to push the crosshairs down. Is this because the erector is in the middle where the image and crosshair is upside down and hasn't been turned right side up yet at the ocular? Thanks. |
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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I don't spend much time worrying about how sausage is made, I just eat. If you are unsure, you can always anchor the gun, pointed at a grid, and turn the elevation turret and watch what happens. I have a bore sighter and do just that when installing new scopes. It will show movement direction and distance.
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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You're missing the main point Rancid - I want to know for sure on scopes without target turrets if up elevation on a CCW turret moves the erector up AND AWAY from the spring.
If I need to adjust up elevation or right windage, then whatever adjustment I need to make, I want to go past a couple extra clicks and then come back into the spring that same number of extra clicks. It's as simple as that.
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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I get it,but is this a problem or a potential problem?
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GiantGreg
Optics Apprentice Joined: February/22/2018 Status: Offline Points: 68 |
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I think your over thinking this. Knowing and understanding the internal mechanics are irrelevant. I think what you are actually wanting(whethere you realize it or not) is a tall target test. If you dial 5, and get 5 then dial 10, 15, etc. If your off, then your off. It either tracks or it doesn't.
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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That may be for you, but not for me. Whats wrong with wanting to understand how something works? It's not rocket science to realize if you need up elevation to have a poi hit higher on the target. But that action involves the erector tube to lift up, this is contradictory to moving the reticle's crosshair down to accomplish a higher POI. The only solution I can think of is because the image is upside inside the erector tube and up is actually down - Occum's Razor? All I need is a yes to confirm that, and if it's not, please explain that as well. Seems like a simple request to me. Hopefully Koshin can chime in. Edited by tpcollins - June/15/2018 at 07:58 |
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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So... this is a theoretical unmarked turret and this has been a purely academic discussion?
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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I just want to understand the mechanics behind the raising of the elevation turret that allows the erector tube to lift also - but the crosshair has to move down to raise the POI. So do YOU know if that's because the image is upside down in the erector and up is really down?
I don't mean to be rude but if you can't answer that question I don't need a reply to something that doesn't relate to the question. Obviously you don't know either or you would have explained how it works.
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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I sent an email to a contact at Vortex and he explained exactly how it worked. I'm all set.
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
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A couple of points on the backlash issue.
Generally, regardless of whether the turret is CW or CCW, the erector is moving in the same direction for adjusting up. The threaded stem will have different threading for different turrets. If you are worried about backlash, you should be worried about regardless of the direction of the adjustment. ILya
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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Thanks Koshkin, if the erector moves up for UP elevation with either a CW or CCW turret, I can prevent any potential backlash from now on.
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
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Why does it matter to you if the erector is moving up or down? If the system has backlash, it will be there in both directions.
ILya
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tpcollins
Optics Journeyman Joined: January/12/2009 Status: Offline Points: 428 |
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According to the bench rest shooters, UP and RIGHT moves the erector tube AWAY from the spring. They say if you need 6 clicks UP elevation, then go 10 clicks UP and then DOWN 4 clicks so the turret ends up pushing against the erector - and especially the spring. Right, wrong, or indifferent - they claim it eliminates waiting for the scope to "settle in". And that's what I do. A lot of us use something to tap on the turret afterwards as an extra step to eliminate the need for the scope to settle in (backlash), as I don't like wasting ammo when I'm at the range. All of my scopes seem to have CCW turret for UP elevation, but I have a Zeiss Duralyt the is CW for the UP elevation - actually it's an ASV target turret that doesn't go up or down when turning - which is why I was wondering if the erector moved up for UP elevation on both CCW and CW type turrets. Since I've learned how the erector tube actually works now, and if both CCW and CW turrets raise the erector up for UP elevation - I'm good. |
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
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This comes from old Leupold target scopes (and some new ones) that had issues with the erector movement. The problem also still persists in some newer scopes that are not designed for frequent turret twisting.
If you plan to spend a lot of time spinning turrets, get a scope that does it well. Trying to deal with backlash in a modern world where there are many scopes that do not have backlash is a little silly. For what it is worth, old Leupold target scopes had backlash going both ways: going away from the spring, and toward the spring. Leupold got away with it for many years because they did not have much competition. That is not the case any more. ILya
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supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
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ACOGs seem to have this issue. All 4 of the ones I have owned I have had to either tap with something or fire a shot to get them to settle. Drives me nuts. But where they are set and forget scopes, I deal with it.
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koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
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They were never designed to be adjusted with any regularity.
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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It doesn’t matter the brand or price point of the scope. If the erector tube is being raised up, point of impact is being shifted DOWN and vice-versa. It doesn’t matter whether the turrets are CW or CCW rotation; that’s just an issue of whether they use a right hand or left hand thread. The erector (and with it the reticle) is always being shifted in the OPPOSITE direction of desired point of impact shift. Just set your rifle in a rest and aim at a target. When you turn your elevation knob and you see the reticle moving upward on your target, that is in fact DOWN elevation correction. The same is true of your windage knob. If you turn the knob and see the reticle moving toward the left on your target, that is RIGHT windage correction. The reticle must always physically move in the opposite direction of your desired POI change. If you have a scope with unmarked knobs, once you do that exercise, you can then mark some kind of direction indicator accordingly. Just remember you should mark the indicator in the direction of POI shift, not erector movement direction, which is always the opposite. To confirm what I’m telling you, repeat this exercise with scopes that are marked, and you will see this is always the case. The reticle must always be moved relative to the target image in the OPPOSITE direction of POI change. This is because when you move the reticle in any direction then use that shifted reticle as point of aim, you then shifted the position of the RIFLE (and with it, the barrel bore) in the opposite direction of change, moving your POI along with it. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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