Confused about Second Focal Plane

[Seeking_Coyotes]

Using the Nightforce ATACR w/ the MOAR recticle as an example, would someone have mercy on a newbie and help me to understand a few things. Here is what I am wondering.

1.) I read that second focal plane scopes can only be used on one specific power otherwise math needs to be done which sucks up valuable time. Is this correct?

2.) What power is this scope set at?

3.) If I sight in a load at 25 power and shoot to verify the table say every hundred yards out to a thousand, if I go hunting and want to shoot a 15 power since an animal is much larger than a target, what will happen with the bullet impact? Will it be dead on or will I miss because I didn't do some math?

Everyone raves about this scope so I think I must be missing something? I understand the Schmidt and Bender is in the front focal plane.

 

[jelrod1]

For ranging with the reticle, hold overs with the reticle, or wind holds with the reticle, yes it must be at a certain power with a SFP scope. It will be in your manual and probably marked on the scope what power that is. The benefit is that the reticle doesn't get thicker and thinner as the power goes up or down like FFP. The benefit of FFP is that you can range and hold at any power.

 

[GSPV]

The difference between FFP and SFP is that the FFP can be used for range estimating using mil dot or similar on all magnifications without scaling for the different power. That's an advantage when you are shooting targets of known size at unknown ranges.

In a SFP, the reticle does not grow with magnification. That's an advantage shooting small things at long, but known distances. Well, known some way other than estimating with the reticle. Like known distance matches, or where you can use a rangefinder.

 

[Seeking_Coyotes]

I am really hoping question 3 is not so or second focal plane scopes are not for me.

 

[Jay Christopherson]

Your point of impact will not change at different zoom settings. The size of your target vis. a vis. the zoom setting on your SFP variable scope has no correlation (i.e., it doesn't matter how big or small the target is, the bullet will impact where the crosshairs are pointing, assuming you have sighted it in correctly).

 

[brian427cobra]

I used to have a NF 5.5-22x50 NP-R1 scope on my 308win, the SFP reticle was correctly calibrated at 22x, at 11x everything doubles, and at 5.5 quad, no matter what power setting each click was 1/4moa, for instance if I was shooting 1000 yards and needed a 2moa hold for wind, at 22x I would hold the first hash which was 2moa, if I had my scope at 11x the first hash mark would be 4moa, and 5.5 would be 8moa. No matter which system we use(MRADs MOAs IPHYs) ranging is possible but horizontal or elevation holds with great precision are what the reticles with hashes are used for, when I shot F-class I would use the NP-R1 reticle to give me corrections based on the shot spot, the reticle is a calibrated ruler, having the reticle and scope knobs in the same unit of measurement is critical.

 

[GSPV]

In 100-300 yard score benchrest, we all use SFP scopes, a large reticle being worse than useless. Around here, they call the X "the chigger" for a reason. It's very small. Very. And if you can't hit the X more often than not, you are not going to win, place or even show.

 

[boyscout]

Your point of impact will not change at different zoom settings. The size of your target vis. a vis. the zoom setting on your SFP variable scope has no correlation (i.e., it doesn't matter how big or small the target is, the bullet will impact where the crosshairs are pointing, assuming you have sighted it in correctly).

Wrong. As you decrease the power in a SFP scope with a hold over reticule your point of impact will rise.
Power setting do matter on a SFP scope.

 

[jelrod1]

Your point of impact will not change at different zoom settings. The size of your target vis. a vis. the zoom setting on your SFP variable scope has no correlation (i.e., it doesn't matter how big or small the target is, the bullet will impact where the crosshairs are pointing, assuming you have sighted it in correctly).

Wrong. As you decrease the power in a SFP scope with a hold over reticule your point of impact will rise.
Power setting do matter on a SFP scope.

You are going to have to cite some documentation to prove that. It is simply not true. POI wont change unless you are holding over or holding wind with the incorrect power setting.

ETA: If your zero is set on 42 power to the crosshair it will be the same at 12 power or whatever. If you want to hold elevation or wind with the reticle then it has to be at a certain power.

 

[BoydAllen]

The difference between first and second focal plane has to do with the apparent size of the reticle at different magnifications, and whether the value of the graduations on the reticle, as well as whether the point of impact will move slightly with power changes. Generally, with quality 2nd focal plane variable scopes, if you sight in at the highest power, any change in point of impact at lower powers will be slight and functionally insignificant, given that lower powers are generally used for closer targets. First focal plane scopes do not have any shift in POI associated with changes in magnification.

With regard to the apparent size of the reticule, the relation of the size of the target to the size of the reticule ,as the power is changed, is different for each type. For first focal plane, the reticule magnifies with the target, maintaining a constant value for the distance between reticule graduations no matter what the magnification. At higher powers, the reticule covers up more of the target than a second focal plane reticule would, and appears "coarser" as a result. This is why second focal plane reticules are much more popular with the majority of users. With the advent of excellent laser rangefinders, and reliable turret adjustments there would seem to be little advantage to using a reticule for ranging, and so this method is generally restricted to competitions where it is required, and for those FFP combined with a mil dot reticule has the advantage of ranging being able to be done at any power. If one is using reticule divisions for hold over or hold off for wind, if the scope is SFP a chart could be produced that would give the value of graduations at different magnifications, but given the quality of turrets in high dollar scopes I think that it would be better to have a chart of comeups taped to one's butt stock, or a calibrated scope turret. It seems to me that scope manufacturers sometimes clutter up reticules in an effort to load up their scopes with "features" that in some cases may not have much practical value, but that is just one opinion.

 

[Romulus]

You have a fine scope and can use this Second Focal Plane scope very flexibly but there are some things you need to know.

You can "use math" to shoot off your MOAR, NPR1, or any reticle that you know the subtensions/measurements of at different magnifications. I do it all the time and I enjoy the flexibility but there are situations, disciplines, and mindsets that some people may be better off with a First Focal Plane. I'll explain how to use a Second Focal Plane reticle on different magnifications later. This means you can also mess up shots as well.

• Too many hunters hunt with Second Focal Plane scopes using BDCs and shoot on any magnification ignorant and sometimes vocally denying any ill effects. I see it all the time. You need to understand your equipment before going hunting or shooting at anything really.

PREFACE: The "SCOPE CENTER/ CROSSHAIRS" should be the same at any magnification on most high end scopes. So shooting off the crosshair or dialing your turrents you can shoot safely from the crosshairs on any magnification. This is how most "long range hunters" do it solely since they saw it on the TV. If you dialed 10 MOA up from your zero the lines below would be 11,12, and so on. Above the crosshair would be -1 or 9 but only on range power that should be listed in your owners manual or marked on your scope.

1) You can definitely mess up a shot if your scope's "RANGE POWER" is max power like 25x AND you use your mil dots or "hashmarks" to compensate for a shot while on a different magnifaction.

2) I do not know the ATACR's range power designated, but since I have a handful of Nightforces I would guess it is max magnifaction or 25x. The easy way to check this is to read the owner's manual, but you can easily check your reticle against a target of known size and a known range. If you have the MOAR a 1 inch cube would take up 1 hashmark at 100 yards (MOA is actually more than 1"/100 yds but that is not important right now).

3) If you Proof a range card to 1000 yds and have repeatable results you can hunt with your scope on RANGE POWER or any power if you are disciplined, have enough brains, and practice enough - OR you can shoot off your crosshair and dial in your adjustments.

USING VARIABLE MAGNIFICATION ON SECOND FOCAL PLANE SCOPES:

• For illustration purposes let's take Nightforces 5.5-22 NXS scope with MOAR.

• 5.5-22x: If the MOAR on a 5.5-22x shows 20 moa below the crosshair where you zeroed your rifle you can use these lines on RANGE POWER using your proofed range card because the 20 MOA represented = 20 MOA at range power.
• If you turn this scope down to 11x you have effectively turned your gradations into 2moa per line, so you have 40 MOA. The first line below the crosshairs represents 2 moa adjustment.
• If you turn this scope down to 5.5x you have 4 moa per line which would only be practically useful to measure things at range or to provide cover fire in my opinion.
• If you have a scope like an 8-32x or 12-42x Nightforce NXS with RANGE POWERS of 22x the opposite effect would happen if you used 32x or 42x magnification and shot off of the Reticle's gradations. 22/32 = 0.6875, so if you thought you were making 20 MOA of shooting adjustment while shooting off the reticle on 32x you actually only adjusted 13.75 MOA (20 x 0.6875 = 13.75). For some reason people act like this is nonsense or rocket science but it is not hard at all and works. If people cannot handle reality then they need to stick to "dialing" or shoot FFP scopes and have respect for game and safety.

These adjustments to magnification effect all hashmarks/gradations/mildots all over the scope EXCEPT SCOPE CENTER.

I can write up a formula so you can develop "RANGE CARDS" for different magnifications on your scope, but if you have read and understood this, creating your own should be intuitive and rather simple now.

Second Focal Plane scopes are very useful and flexible by people who shoot enough to know how to use them. The only place I can see one absolutely needing a FFP scope is in some kind of competition where you cannot or are not allowed to adjust your scope or dial for windage and elevation. Know your equipment and become versatile so you can deal with anything.

For really long range target shooting like shooting beyond a mile with most cartridges you can also buy 20-40 MOA scope rails & even add 20 MOA "unimounts" to achieve more adjustment range. There are a handful of luxury scopes with large adjustment ranges but to really get out there you will probably need help. Doing this there will be no way to zero your rifle at 100 yds or 400 for that matter - UNLESS you utilize the magnification range of a Second Focal Plane scope to utilize the hashmarks of the top stadia above your crosshairs on a lower power like half magnification or less. You may run into a wall but if you understand the principles you will be able to create a solution. This would be hard to achieve with a scope without gradations on the vertical stadia (like most bdcs and a few tactical reticles) unless you had a great optic mounting system that was very square and zeroed your scope 400-600 yds kind of blind firing ???

Overall, enjoy the hell out of that ATACR. It's a scope most wish they could utilize.

And, I don't think you would do this, but I've seen more than one guy that thought his MOA demarcations on his multiple NIGHTFORCE scope turrets were yardages for adjustment!!! He said, "well that's how they do it on [the TV"] ;D Remembering that always brings a smile and a tear to my eye. Have fun shooting.

 

[Jay Christopherson]

Your point of impact will not change at different zoom settings. The size of your target vis. a vis. the zoom setting on your SFP variable scope has no correlation (i.e., it doesn't matter how big or small the target is, the bullet will impact where the crosshairs are pointing, assuming you have sighted it in correctly).

Wrong. As you decrease the power in a SFP scope with a hold over reticule your point of impact will rise.
Power setting do matter on a SFP scope.

Re-read it my answer and then re-think your post - I never said the holdover doesn't change. Clearly, if you are using hashes to hold off or over, it will. I said the POINT OF IMPACT (i.e., where the crosshairs are centered) doesn't change.

 

[02bAdam]

This SFP calculator might help

https://docs.google.com/spreadsheet...e4HL1l6CJMTpRs13I8InBuFHrw8/edit?usp=drivesdk

 

[JMayo]

Simple answer ...
You see deer. Your not not sure how far. You turn scope to the correct setting in manual. Look at deer, use hash marks to get an idea how far he is.
You've shot rifle, you know what it's zeroed at. If needed You crank scope to high power, adjust your poa to compensate for distance (hold over) and shoot.

That's my way ....

 

[Alexander-M]

(Partial Quote)

. . . Generally, with quality 2nd focal plane variable scopes, if you sight in at the highest power, any change in point of impact at lower powers will be slight and functionally insignificant, given that lower powers are generally used for closer targets. . .

Boyd,
Many times I, as do others, turn our scope magnification power down when the mirage is bad and makes it difficult to see the target clearly. I have frequently turned my NF-Comp down from 55 to 35, an perhaps lower, to get a clearer target picture. Using an objective cover with the stop hole (from Dan Pohlabel) helps, but I still have to decrease the power.

Is there a potential POI change that would be appreciable say at 600 or 1000 yards?

Thanks!
Alex

 

[BoydAllen]

(Partial Quote)


Boyd,
Many times I, as do others, turn our scope magnification power down when the mirage is bad and makes it difficult to see the target clearly. I have frequently turned my NF-Comp down from 55 to 35, an perhaps lower, to get a clearer target picture. Using an objective cover with the stop hole (from Dan Pohlabel) helps, but I still have to decrease the power.

Is there a potential POI change that would be appreciable say at 600 or 1000 yards?

Thanks!
Alex

Any POI change should be proportional to the distance, so you can test for it under good conditions at 100 yards and multiply to get what it would be at longer ranges. Ideally, it would be good to have a rigid mount to put the scope in so that you could hold the scope perfectly still while making magnification changes while looking for reticle movement on target.

 

[rammac]

You've got a second focal plane scope and you're hunting deer:

1. You see deer.
2. You turn scope to the correct setting in manual.
3. Use the reticle hash marks to ESTIMATE the range.
4. ESTIMATE your hold over distance using the reticle hash marks.
5. Take the shot and HOPE that you've made all the right ESTIMATES.

On the other hand with a first focal plane scope:

1. You see deer.
2. You shoot the range ACCURATELY with your range finder.
3. Either adjust your scope ACCURATELY for the range or use an ACCURATE hold over using the reticle hash marks.
4. Take the shot KNOWING that you've made PRECISE adjustments.

To each their own and depending on the type of shooting you are doing one type of scope will be more appropriate than the other but for me, a western Montana hunter, I like the first focal plane scopes. As a hunter, under 200 yards on elk or deer, I couldn't really care any less what the actual range is, my bullet's trajectory will stay well within the kill zone of my game animal. As my shot goes out farther it becomes more important to know exactly what the range is and what scope adjustment is required. There are far too many other variables when you take a shot at a game animal beyond 300 yards and I don't want to have to worry about whether I guessed the range correctly, if I set the magnification correctly, and did I use the right amount of hold over.

 

[Alexander-M]

Any POI change should be proportional to the distance, so you can test for it under good conditions at 100 yards and multiply to get what it would be at longer ranges. Ideally, it would be good to have a rigid mount to put the scope in so that you could hold the scope perfectly still while making magnification changes while looking for reticle movement on target.

Good idea - I'll do that.
Thx!
Alex

 

[ToddKS]

Using the Nightforce ATACR w/ the MOAR recticle as an example, would someone have mercy on a newbie and help me to understand a few things. Here is what I am wondering.

1.) I read that second focal plane scopes can only be used on one specific power otherwise math needs to be done which sucks up valuable time. Is this correct?

2.) What power is this scope set at?

3.) If I sight in a load at 25 power and shoot to verify the table say every hundred yards out to a thousand, if I go hunting and want to shoot a 15 power since an animal is much larger than a target, what will happen with the bullet impact? Will it be dead on or will I miss because I didn't do some math?

Everyone raves about this scope so I think I must be missing something? I understand the Schmidt and Bender is in the front focal plane.

What is your intended use for this scope? That is what will determine whether 1st or 2nd focal plane is appropriate.

Your zero will not change based on selected magnification regardless of whether the scope is 1st or 2nd focal. The only difference is in how the reticle subtends.

To use your MOAR example, in a first focal plane scope the distance between the hash marks will be 1 MOA regardless of the magnification setting.

In a second focal plane scope (we will use a 22X scope as an example) the reticle subtends at a single setting. In the case of a 22X NF scope, that setting is 22 power. This means that at 22 power the distance between the reticle has marks is 1 MOA but at any other setting the distance changes. At 11X the distance becomes 2 MOA and at 5.5X the distance becomes 4 MOA. If you are wanting to use the reticle for wind or elevation holds you would need to be at 22X, 11X, or 5.5X or the math gets into decimals that you don't want to deal with.

I have both first and second focal plane scopes. The above is from my direct experience with a 5.5x22 NXS and is also the reason that I own a Gen II Vortex Razor and NF ATACR F1 7x35 now.

 

[4xforfun]

You've got a second focal plane scope and you're hunting deer:

1. You see deer.
2. You turn scope to the correct setting in manual.
3. Use the reticle hash marks to ESTIMATE the range.
4. ESTIMATE your hold over distance using the reticle hash marks.
5. Take the shot and HOPE that you've made all the right ESTIMATES.

On the other hand with a first focal plane scope:

1. You see deer.
2. You shoot the range ACCURATELY with your range finder.
3. Either adjust your scope ACCURATELY for the range or use an ACCURATE hold over using the reticle hash marks.
4. Take the shot KNOWING that you've made PRECISE adjustments.

To each their own and depending on the type of shooting you are doing one type of scope will be more appropriate than the other but for me, a western Montana hunter, I like the first focal plane scopes. As a hunter, under 200 yards on elk or deer, I couldn't really care any less what the actual range is, my bullet's trajectory will stay well within the kill zone of my game animal. As my shot goes out farther it becomes more important to know exactly what the range is and what scope adjustment is required. There are far too many other variables when you take a shot at a game animal beyond 300 yards and I don't want to have to worry about whether I guessed the range correctly, if I set the magnification correctly, and did I use the right amount of hold over.

Of course, we all know that you can't use a range finder when you have a secon

You've got a second focal plane scope and you're hunting deer:

1. You see deer.
2. You turn scope to the correct setting in manual.
3. Use the reticle hash marks to ESTIMATE the range.
4. ESTIMATE your hold over distance using the reticle hash marks.
5. Take the shot and HOPE that you've made all the right ESTIMATES.

On the other hand with a first focal plane scope:

1. You see deer.
2. You shoot the range ACCURATELY with your range finder.
3. Either adjust your scope ACCURATELY for the range or use an ACCURATE hold over using the reticle hash marks.
4. Take the shot KNOWING that you've made PRECISE adjustments.

To each their own and depending on the type of shooting you are doing one type of scope will be more appropriate than the other but for me, a western Montana hunter, I like the first focal plane scopes. As a hunter, under 200 yards on elk or deer, I couldn't really care any less what the actual range is, my bullet's trajectory will stay well within the kill zone of my game animal. As my shot goes out farther it becomes more important to know exactly what the range is and what scope adjustment is required. There are far too many other variables when you take a shot at a game animal beyond 300 yards and I don't want to have to worry about whether I guessed the range correctly, if I set the magnification correctly, and did I use the right amount of hold over.

Of course, we all know that you are not allowed to use a range finder when you have a SFP scope.