I am currently looking for a new scope for long range hunting and target shooting.I am really confused with the first and second focal plane bit.From what I can understand is that your zero will not hold true through all ranges of a variable power scope.Lets say on a ten power scope I am zero at 300 yards on ten power.how much does point of aim change at different powers?Is there a formula for this,or is the change in point of impact to little to worry about?I am looking to be within the 6 to 800 dollar range possibly 1000 for a scope.Im open to any suggestions.
second focal plane scopes
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Zero stays the same on both. I have many scopes of each type. The difference is in that the scopes with the reticle in the first (front) focal plane, when you increase the power, the reticle increases in size along with the image. This is great if you are using a mil-dot since the mil-dot will work at all power settings. On scopes with the CH in the second (rear) focal plane, the cross hair says small as the image increases but a mil-dot will only be accurate at one particular power, usually 10X.
All of mine hold zero perfectly all across the power spectrum. I suppose if you bought a $20 Wal-Mart special or other Com-block POS it may not hold zero as you increase power but it has nothing to do with the CH being in the first or second focal plane.
All of mine hold zero perfectly all across the power spectrum. I suppose if you bought a $20 Wal-Mart special or other Com-block POS it may not hold zero as you increase power but it has nothing to do with the CH being in the first or second focal plane.
On any decent scope or for that matter almost all scope your zero wont change with magnification. A first focal plane scope will change the size of the crosshairs in direct relation to the zoom so if you use mil dots for rangefinding you can use them at any zoom range. A second focal plane scope keeps the crosshairs the same size so if you use mil dots you can only range find at one set power. I prefer a first focal plane scope but they do cost more.
Ok..Now I understand that part of.thank you.My next question would be thisIf I am zero at 300 which i currently am.if I use my mil dots strictly as yardage markers for example.third dot 600 4th dot 700.am i correct in saying that it will stay consistent through out the power range?
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First of all that is not how a mil-dot reticle is designed to be used. But let's say that is the way you want to use it and you construct a range table and it just so happens that your center CH is zeroed at 100 and it turns out the first mil-dot down is zeroed at 200, the second at 300, and the third at 400, then if it it a first focal plane cross hair (reticle enlarges as does the target as you increase power) then no, your zero with the lower dots will not change. But if you did that with a second focal plane (target enlarges but cross hairs stay the same size) then yes, your zero would change with the lower aiming points and would only be accurate at the particular power at which you constructed your range table.
Mil-dots are used for range finding and judging where to hold off at long range and where to hold off due to wind, not to sight in where the center is zero at 100, first dot down is 150, second dot 200... For that type of use it is better to use a reticle set up for that purpose. The mil-dot is not intended to work for the application you described.
The type of reticle and use you are talking about is an excellent example of the Leupold Long Range reticle, where you have two dots below the cross hair, then you do use them as alternate zeros for longer range. Zero the main CH at any power but use the ranging dots only on the highest power setting.
It is set up to zero the cross hair at 200 then the first dot below the cross hair is zeroed for 300 and the second is for 400. This can vary slightly from cartridge to cartridge so you must verify by live fire but the system ONLY works on the scopes highest power setting.
Here is a link as to how the Leupold LR reticle works.
A lot of people like mil-dots for the sake of the way it sounds but have no idea on how to actually use it. The mil-dot works for any caliber or any velocity weapon but you must know your particular zero and trajectory, whereas the multiple zero reticles only work within a certain velocity range and if you round falls outside that range you have to construct your own ballistic table.
Books have been written on how to properly use the mil-dot and it is too involved to explain in a thread. The best bet is to download a manual on mil-dot use and read it.
A short answer is first you use the mil-dots to determine range, then knowing the trajectory of your rifle you use the mil-dots again to judge hold over and windage. For a first focal plane reticle it works at any power. For a second focal plane it works only at one power, usually 10X.
Here is a link that tells you how to use a mil-dot. It sounds complicated but once you get use to it one can use it very quickly and as I said, .22 LR or .50 BMG, it works the same.
Mil-dots are used for range finding and judging where to hold off at long range and where to hold off due to wind, not to sight in where the center is zero at 100, first dot down is 150, second dot 200... For that type of use it is better to use a reticle set up for that purpose. The mil-dot is not intended to work for the application you described.
The type of reticle and use you are talking about is an excellent example of the Leupold Long Range reticle, where you have two dots below the cross hair, then you do use them as alternate zeros for longer range. Zero the main CH at any power but use the ranging dots only on the highest power setting.
It is set up to zero the cross hair at 200 then the first dot below the cross hair is zeroed for 300 and the second is for 400. This can vary slightly from cartridge to cartridge so you must verify by live fire but the system ONLY works on the scopes highest power setting.
Here is a link as to how the Leupold LR reticle works.
A lot of people like mil-dots for the sake of the way it sounds but have no idea on how to actually use it. The mil-dot works for any caliber or any velocity weapon but you must know your particular zero and trajectory, whereas the multiple zero reticles only work within a certain velocity range and if you round falls outside that range you have to construct your own ballistic table.
Books have been written on how to properly use the mil-dot and it is too involved to explain in a thread. The best bet is to download a manual on mil-dot use and read it.
A short answer is first you use the mil-dots to determine range, then knowing the trajectory of your rifle you use the mil-dots again to judge hold over and windage. For a first focal plane reticle it works at any power. For a second focal plane it works only at one power, usually 10X.
Here is a link that tells you how to use a mil-dot. It sounds complicated but once you get use to it one can use it very quickly and as I said, .22 LR or .50 BMG, it works the same.
With a first focal plane the mil dots will be constant, a second focal plane they will vary with power. Unfortunatly a mil dot really cant be used as a yardage marker by itself, you have to know the size of your target and do some math. It sounds harder than it really is.
http://www.mil-dot.com/Content%20Images/The_Derivation_of_the_Range_Estimation_Equations.pdf
http://www.mil-dot.com/Content%20Images/The_Derivation_of_the_Range_Estimation_Equations.pdf
Thanks guys.I understand the ranging with mil dot.I drove myself half crazy on the internet trying to learn.I was just using what I said as an example to figuring out the huge difference between first and second focal planes and which was goin to be better for the shooting I do.Thanks again for your time fellas.
My personal preference is MOA over Mil Dot, and I prefer SFP scopes.
Any scope that gives you something in the reticle you can base a measurement from can be use to figure and approximate range. As long as you have a known reference on that object. Say for instance, a deers chest is approx 18 inches, a mans torso is approx 38 inches, you can use the zoom or the amount of space used between what you're using in the scope for measuring to come up with a yardage, just have to use a little Fine Country Gentleman engineering. Now, a plain. one size cross hair scope ain't gonna do this because there's nothing in there to guestimate and measurement from.
Any scope that gives you something in the reticle you can base a measurement from can be use to figure and approximate range. As long as you have a known reference on that object. Say for instance, a deers chest is approx 18 inches, a mans torso is approx 38 inches, you can use the zoom or the amount of space used between what you're using in the scope for measuring to come up with a yardage, just have to use a little Fine Country Gentleman engineering. Now, a plain. one size cross hair scope ain't gonna do this because there's nothing in there to guestimate and measurement from.
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