Home Forums Hunting & Shooting Hunting Optics 1st vs 2nd Focal plane?

Can you explain this in more detail?

I have both FFP & SFP scopes I prefer FFP scopes

You answered your own question — I doubt I’ll ever take a 500 yard shot hunting. The only time FFP reticles aren’t terrible is when shooting over 500 yards. Don’t do it.

I'm with Jordan Smith on this one; I'm also looking for more detail about the bolded statement.

And I'm with JS and FTR as I'm always open to learning new things. By optical challenges I assume, though don't agree, that he means a large reticle at high power that may obstruct a small target and a small reticle at low power that may be difficult to see. I'm not trying to put words in his mouth, I'm just assuming that's what he means. However, I'm lost on the "aberrations" portion as, to me, that is scope specific irrespective of type of reticle based on components.

If anyone wants to try a quigley-ford i have a new in box 5-20-50 . Reticle is cut for 7mag nosler accubond 168 grain factory ammo. 1000.00 buys it

How does that do at 10 feet?

I agree.
The nice thing about SFP is you can adjust the magnification to adjust the reticle subtension to match your target. For example, a scope with a circle-dot reticle. Sometimes conditions are such that the dot is visible and you want to use that. Other times, like crappy light conditions, you want to use the circle like an aperture. Depending on your preferences, you may have to adjust the magnification to get your preferred line of white around the bull.
Same thing applies to dots & crosshairs - you can adjust the magnification to give you a better sight picture instead of, for example, having the reticle totally subtend the target.

Yes but with FSP and a non variable scope with adjustments that match the reticle there is no need. And in the past I have adjusted the magnification to give me a reticle I could use as a rangefinder.

Here is why -

When the cross hair is in the back the light path is directly centered of the lens where the cross hairs are and the least amount of lens distortion is…

With FFP you are moving the cross hair through the path of the light to bend it…. Rut-Roo..
So the path correction is using not exactly center portion of the lense to bend it back to focus the light back to the center or the second rear plane.

Just like any other lens if it’s NOT passing directly through the center you get some aberrations

I had a national BR champ tell me that, and looked for it glass in my FFP PRS BR rig vs. a SFP model of the same type..
…. and dang it .. he was right.

It’s a TINY difference - but under pressure at 1k yards with mirage or clouds and low light - every little bit comes in to play

Thanks for the reply and information Spotshooter. I'm going to have to cogitate on that a while. Interesting.

That doesn’t make sense to me. I’m not an optical engineer, and I don’t work for a scope manufacturing company, but it seems to me that the magnification mechanism is moving a lens assembly that is separate from the first and second focal plane lens assemblies. Therefore, the lens with the reticle in it shouldn’t move, regardless of which plane it is in. I’m still not convinced that optical aberrations (which type are you referring to, exactly?) are inherently greater in FFP designs compared to SFP designs.

a LOT depends on the scope maker…

What I’m really talking about is “sharpness to the edges” … of how a picture is sharp all the way across.

But I’m not a teacher, and I validated things to my satisfaction..

I use FFP on my PRS rifles. - but my Bench rifles and ELR rights are SFP

The fact that both the FFP and the SFP are focal planes (both planes are located at the focal length of the preceding lenses in the system) contradicts your notion that the reticle lens moves away from the focal point in a FFP reticle system. Methinks you noted an anecdotal instance of a design difference between a SFP scope and a FFP scope, and are now claiming that that the difference you noted is caused by a universal property of FFP versus SFP designs.

Optical aberrations of various types have specific causes, and are not just generic labels for "edge-to-edge sharpness."

I don’t care about winning an argument… I only shared an observation that I validated and tried to explain why the best I could. I did semi-pro photography, and I’m got a half decent eye so I can tell you that at least with a couple scope makers at a 1k yard bench rest matches where I compared the FFP & SFP scopes of like types last year … I could see more crisply with the SFP.

Sorry if that sounds cold but I could give a hoot if you don’t believe me… Go check for yourself. Of course I’m talking about scopes that are WELL over a grand… so for cheaper models I really have no Idea. Not everyone rocks a scope that costs a couple grand, not to mention multiple ones…
You darn near have to quit hunting to afford stepping into serious LR shooting.

Smartest thing a man can do in life is walk away from guys that “like to argue”.., who are all about “winning.”
I’d remarry a boss chic if I liked that kind of BS. … NAH

Cheers ! (Yes that was Sarcasm for those on their first cup of coffee)

You can point your barrel at something 10' away and get the job done. At 20 yards they're plenty usable if you keep your eyes on the target while mounting the gun.

SS:

Your initial post in this thread definitively stated that the phenomenon you're describing obscures targets at the yardages specified by the OP to the extent that it should be the overriding factor in reticle plane decisions. I don't think Jordan and others, including me, who haven't noticed obfuscating aberrations inherent to FFP reticles to the extent that you described are "arguing for the sake of arguing" by trying to gather more information.

I was comparing nightforce competitions to NXS …. Are high magnification in hard conditions multiple times.

Like I said… a lot is in the maker’s build

I could resolves things much better in the competition…. But maybe one shouldn’t bring a tactical FFP scope to a Benchrest match…

Just saying ..


- for your point Starbuck
GLASS and COATINGS ARE EVERYTHING.. when it comes to clarity… … So what you guys are really discussing is does putting the cross hairs up front or in the back of a moving tube make building a optical system harder or easier (all relative terms).

I said harder because it puts more critical components into a smaller moving space so it tightens the requirements for the build.

BUT - engineering (I am one) is what it is… some groups are run by Engineers some are run by accountants…. And if you actually have experience in the corporate world you know the Marketing groups run both of you ….

So results will vary.. Go sit behind the scopes in real world conditions and all the BS goes away…


MY POINT - Even if it’s more challenging to build a FFP clarity wise - that doesn’t mean people don’t or won’t…

Go test what’s on the market with your own eyes … Experience is king.. Engineering - Seriously I am one and the right thing doesn’t always happen.

All the NXS (except the 3.5-15x50 F1 model) are SFP and so is the competition. They have different grade glass and magnification. Apples and oranges.

I would say that whatever someone else uses to shoot game or competition doesn’t mean anything to me. The difference in the appearance of the crosshair is what matters, and I don’t like the European or number 4 reticle.

I will continue to use a second focal plane scope for all it’s virtues regardless of it’s inadequate scale at various power on a variable scope. Personal preference really doesn’t have any bearing on the effects of a ffp vs a sfp scope…