Help with first and second focal planes

[CANNONMAN]

I want to get more into long range shooting and I like Vortex and Night Force. Night Force has a 12x42x56 NXS which seems to something I interested in. My feeble understanding is that on a second plane scope the POI will change with focal distance. Help or links please. And/or thoughts on other scopes to look at?

 

[MErl]

The POI doesn't change (hopefully). What changes is the relative scale of the crosshair and the target. If the scale is constant (FFP) then marks on the crosshairs can be used for holdover at any magnification.

Some people don't like FFP because the crosshair can be hard to see at low magnification or too thick at high.

https://duckduckgo.com/?q=site:Thehighroad.org+FFP+SFP

 

[WestKentucky]

Think of it more as a camera and a TV than as a scope. On a FFP you are zooming in with the camera. Everything in front of you (including the crosshairs) gets magnified and it show's up on the TV. Now, with 2nd focal plane your zooming in with the TV. Sure your still zooming, and the point of aim should stay the same, but your only zooming what's on the TV. Those crosshairs between you and the TV aren't zooming in or out, so relative distance is changing.

So with the FFP scopes 1 dot or mark or whatever sighting system measurement you have stays correct because it zooms with everything else. With SFP scopes, your sight graduations are only correct at the zoom point that you figure out for them, typically minimum zoom. You CAN be just as good with a SFP scope, but you have to practice a lot more to gain the info and then know a lot more numbers at multiple zoom magnifications.

 

[judgedelta]

Having tried both, I prefer a second focal plane used with a rangefinder. Leica Geovid binos. The important thing is to know what your bullet is doing at various ranges...

 

[basicblur]

Have you seen this video explanation?
http://www.vortexoptics.com/video/first_vs_second_focal_plane

I guess it depends on what type of shooting you do.

I prefer FFP - all I had until a few years ago was fixed optics - got my first variable power scope a few years ago, and never realized the BDC values constantly change depending on power setting.

Fer me, that really sucks - if I have a BDC reticle, I want the values to remain constant no matter what power I have dialed up.

After doing my homework, I now buy nothing but FFP scopes.

A bit difficult to do over the years, but folks and manufacturers are slowly catching on.

From what I understand, FFP has always been big in Europe, but SFP reigned on this side of the pond.

I'm starting to hear more and more folks at the local gun shop ask for FFP.

 

[rockyboy]

Thanks. Makes sense. Is the second thing: MOA -v- ???. Sorry for my dumb questions.

 

[taliv]

what second thing? i can't tell what you're asking

 

[Bobson]

Thanks. Makes sense. Is the second thing: MOA -v- ???. Sorry for my dumb questions.

Are you talking about MOA vs Mils?

 

[jmr40]

if I have a BDC reticle, I want the values to remain constant no matter what power I have dialed up.

If I'm shooting at ranges where I need the BDC features the scope will be on the highest magnification setting. The same setting I used to zero the rifle. On variable scopes I see no reason to use any of the settings in the middle. I zero it with the most magnification available and do 95% of my hunting on the lowest magnification. Out to 100-200 yards I don't need more than 2x or 3X and the BDC features aren't needed. If the need arises for more magnification I don't use anything in between. This negates any perceived problems with SFP scopes.

 

[rockyboy]

Sorry, answering for a friend I'm visiting. He's trying to get me into what he's getting into. But yes. What is the difference between MOA and mill dot please.

 

[Bobson]

What is the difference between MOA and mill dot please.

To put it simply, they're two different methods to measure something. One isn't better than the other; just a matter of preference and one's ability to use it properly.

These two videos by Ryan Cleckner explain them well, much more thoroughly than can probably be done with just text:

MOA
Mils

 

[CANNONMAN]

Thank you Bobson. Between youtube and this forum I think I might be learning a few things. I appreciate your direction.

 

[Bobson]

My pleasure. Learned most of my gun-related knowledge by starting right here, myself. Still learning new things here almost every day.