Confused about Second Focal Plane

[farmerjohn]

Now if one of you fellers could tell me exactly where in one of those 2in "splats" that a bullet makes on a freshly painted steel sighter plate at 600yds the bullet actually hits, I'd be happy. Seems I could not find the X ring after trying all weekend at St Louis last week......
Farmer

 

[garandman]

THIS ^ ^ is why I always buy FFP.

 

[Shawnba67]

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

The Crosshairs dont change point of impact measurably at any magnification. The tic marks on the reticle are only 1 moa apart at 1 specific magnification. if mils still only at 1 magnification. If you intend to use the reticle for ranging or windage, I have a FFP Athlon and Im a big fan of the First Focal Plane. I use mine for thousand yard f class and have no issue with the "big" crosshairs at high mag

 

[K22]

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.

Do you mean only if the reticle is being used to adjust the amount of holder over?

For example for a simple duplex reticle on a SFP scope, if you sight in at the maximum magnification of the scope, say at 16X then reduce the power to 8 or 10X for a short shot or to minimize the affects of mirage will the POI change?

PS: Perhaps I was told wrong but I was told, by a Leupold rep, albeit several years ago, that changes in magnification on SFP scope do not change the POI of impact.

 

[muleystalker]

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.

The NF 5.5 -22x 50's reticle is calibrated at 20x. The ATACR's are correct at 25x.

For the OP they make FFP ATACR's if thats what you want.

 

[jghoghunter]

SFP scopes as the Leupold rep. said do not change point of impact when power is changed. Common sense tells you this otherwise these scopes would be totally useless. Look how many of these scopes are out there and how many have set records. I'm certain there are MANY more records set with SFP scopes over FFP.

 

[6and7mm]

In all honesty, folks make this subject much harder than it should be. Both reticle types (FFP and SFP) have their place and preference. If you take the time to learn either, both work well for most every application. Exceptions do come into play. It would be wise to have a Skype conference call on this subject as it so frequently misunderstood. As long as you use the center portion of the reticle -- as the main aiming point, all things are equal using either reticle type. When you begin using the other reference points for aiming assistance, a better understanding of the reticle types becomes most necessary; but it is not as difficult to understand as most folks explain it. We are guilty of over-explaining or over -thinking it...or both

 

[xswanted]

FFP - Your crosshairs and hold over lines will stay the same size and have the same subtensions, relative to the target at any magnification. Meaning if you intend to use the hold over lines in the scope for longer shots, with a FFP reticle it will not matter what power the scope is on. Your third line will always be “x” distance.


SFP - Your crosshairs and hold over lines will get smaller, relative to the target, as your power increases. Your subtensions will cover less hold over and will only be calibrated to a specific power. Meaning if you intend to use the hold over lines in the scope for longer shots, you’ll need to always be on the same power to the lines to equal out. There are ballistics programs (StrelokPro) that will tell you what the lines of a given reticle equal out to be, at given powers, within the app. Ive used it for my Dad as he likes to use a Leupold Varmint Hunter (SFP) for coyote hunting. I gave him the holdovers at 11x and 14x and they come out correctly.

The center of either a FFP or a SFP will always be the same POI on any power.


Having said all this, if your intended purpose is for coyote hunting don’t worry about using the hold over lines. Click the scope up and be done. If you’re shooting at a coyote far enough away where you need to begin to start using anything past the second line, chances are you will have had enough time to range him and click up.

 

[ToddKS]

The NF 5.5 -22x 50's reticle is calibrated at 20x. The ATACR's are correct at 25x.

For the OP they make FFP ATACR's if thats what you want.

NF 5.5x22x50 subtends at 22X, not 20X. I have owned several.

 

[rcs9250]

An easy way to see this with a SFP scope is to draw a vertical line on a piece of cardboard or paper with a Sharpie.
Then draw horizontal hash marks about one inch wide (left to right) and exactly one inch apart (see sketch). Put target at 100 yards and then look through your scope and adjust scope till your 1 MOA subtension lines agree with your targets one inch lines. That should be where the power ring has a dot showing it is one for one at one hundred yards. You can also use some of the commercial sighting targets that have a one inch grid printed on it.
After doing the above process you can put targets at different ranges and see what you learn at different magnification.