FFP Versus SFP: What’s The Difference?
BY Herschel Smith
3 years, 2 months ago
TTAG has what I consider a very good explanation on FFP versus SFP (although we’ve covered that before as well). It’s worth lifting a bit out.
As you may have gathered, first focal plane scopes place the reticle in front of the magnification lens, resulting in a reticle that shrinks or grows as the magnification is adjusted. That means the reticle’s tic marks or gradations always cover the same minutes of angle or milliradians, regardless of the magnification level. The measurements of the reticle are accurate at any magnification.
So your holdovers are correct at any magnification. That’s the upshot.
That can be really useful for rapid ranging or engagement at distances without dialing the magnification up or setting the turrets. While that might be of limited use in a more simplistic reticle, with a mil grid like the HorusVision Tremor or the Schmidt & Bender GR²ID reticles, there is little need to manipulate the turrets once the optic is zeroed.
The shooter can accomplish all adjustments using holds. But those holds would be dependent on magnification in a second focal plane scope. In contrast, the shooter can range, engage, and adjust at any magnification with a first focal plane. It makes engagement far quicker. That might be much more of a tactical consideration than for, say, competition or hunting. But it is still a valid consideration.
In many ways, this choice does depend on your budget and requirements. Many with a sniper background (including the author) still question the point of a second focal plane variable optic. Others argue that the reticle on a first focal plane optic gets too small at lower magnifications and too large at higher, obscuring the target.
So there are downsides too.
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On October 16, 2021 at 12:51 pm, MTHead said:
His last comment was spot on. They do. Also, second focal plane scopes have the advantage/disadvantage of changing reticle subtensions.
If your scope has 2MOA hash marks on 10 power. (ranging power). It has 4MOA hash marks on 5 power. 5MOA hash marks at 2.5 power.
My Nightforce on 2.5 power has 75MOA’s of drop comp. on the reticle alone. Which is very useful in shooting long range sub-sonic blackout rounds. Also, the added exit pupil of lower power allows more light, which aids in sight picture as much as magnification. It’s the only way to overcome having to spend a mint on super quality glass.
I have an old Bushnell elite 6-24x with mil-dot that has a ranging power at 12x. Sounds crazy till you realize that on 6x you have 10 mils. without dialing crap around.
Range, dial power, shoot.
It can be very useful to someone that studies it.
On October 18, 2021 at 12:38 pm, Ned said:
Don’t do much seriously long range shooting these days. It would seem that at long range one would tend to have his magnification dialed all the way up, making FFP less of a requirement, if light gathering wasn’t an issue as described by MTHead. I have both types, and dial all the way up for 300 yds and over with FFP, but usually shoot with plenty of light. I’ve used good glass 2nd focal plane scopes for hunting and always kept them dialed all the way down unless I spotted game. My 2 1/2-10 x Baush & Lomb was very bright at low power with little light. Wondering what seriously long range shooters typically do from the standpoint of magnification.