FFP Vs SFP for Target shooting

Rifle scopes, iron sights and optics. Spotting scopes and target acquisition devices.

Re: FFP Vs SFP for Target shooting

Post by wannabustbunnies » 07 Dec 2019, 10:51 pm

bladeracer wrote:
One thing SFP can do that FFP can't is give you variable subtensions, as I explained about the holdovers changing with magnification. My reticle has holdovers out to 15.4MoA (for a theoretical zero at 600yds with a specific .223Rem load) at 18-power. If I'm shooting a load that requires say 31 minutes (heavier bullet, reduced velocity, a blunt hunting bullet, or simply a different cartridge - like .22LR) I can wind the scope back to 9-power, hold on the same "600yd" sub tension, and voila, I have a 31 minute holdover. Printing a dope card of the variations throughout the magnification range is no harder than any other dope card.

You can also range targets the same way, by adjusting the magnification to fit the reticle to the target, read the magnification, and read the dope. For example, you set out 150mm gongs (roughly the size of a non-helmeted head) at random distances. I'm using a 150mm target simply because it fits easily in metric or imperial ranging, 150mm is roughly 6MoA at 100yds and 5MoA at 100m (so I don't need a calculator for this example, I'm doing this on my phone). My scope has holdovers at 1.7, 4.4, 7.6, 11.4, and 15.4 minutes - at 18-power. At full mag, I put my reticle on the first target and it covers about three-quarters of the height to the second (or 4.4MoA) dot, about 3.3MoA, so I already know the 150mm-tall target (5MoA@100m) is around the 150m mark (at 200m the gong is 2.5MoA remember, so at 150m it's 3.33MoA). If I want more precision, I can adjust the magnification to fit one of the marks as neatly over the target as I can. I can't make the reticle "smaller", so I wind the mag back until the 1.7MoA gap "grows" to cover the target, then read the magnification. In this case it's 9-power, making the subtension actually 3.4MoA. So our 5MoA@100m gong is at about 145m. As my scope has 1MoA dots, I can do the same to make a dot fit over the target instead of the gaps between the holdovers.

It sounds complex, and takes a long while to explain what is not very complex, but with practice it becomes second nature, you can roughly estimate the range as soon as you put the reticle over the target, without having to adjust the magnification, regardless of the type of reticle you use. The most rudimentary version of this is learning the fields of view in your scope at various magnifications, mine goes from 63MoA (roughly one degree) at 18-power to 230MoA at 4.5-power. This is one reason all my scopes are identical, including the reticle - I am familiar with how large things should appear in my scope. Calculating it merely gives you a more accurate range estimate, but if you need precision use a laser.


Take your 150mm target ranging example and with a FFP mil scope just do this on any magnification
images.png
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Like you said though much easier and precise to just use a laser as unless you know the actual target size and are measuring it correctly it's basically just a guess.

bladeracer wrote:But the primary reason to prefer SFP for precision shooting is the fine reticle, whether you're at 4-power or 24-power. You can see the difference in the picture I posted. You can also see how the holdovers change as magnification does.


My FFP reticle thickness is a constant .054 mils (5.4mm @100m) regardless of magnification.
Your SFP with a reticle thickness of eg .125 MOA on max power 18x (3.64mm @100m) is actually 3 times thicker than mine at minimum magnification of 4.5 power (16.37mm @100m)

I think we have come a long way from your original intent though and everyone is free to use what best suits them.
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Re: FFP Vs SFP for Target shooting

Post by bladeracer » 07 Dec 2019, 11:54 pm

wannabustbunnies wrote:My FFP reticle thickness is a constant .054 mils (5.4mm @100m) regardless of magnification.
Your SFP with a reticle thickness of eg .125 MOA on max power 18x (3.64mm @100m) is actually 3 times thicker than mine at minimum magnification of 4.5 power (16.37mm @100m)

I think we have come a long way from your original intent though and everyone is free to use what best suits them.


I would only be using minimum mag while I'm walking in and out of an area, to deal with immediate shots of opportunity, where the heavier reticle is a good thing. My reticle is .25MoA regardless of magnification, 7mm wide at 100m (I have confirmed this myself), 35mm on a fox at 500m, 70mm on a deer at 1000m - whether I'm on 4.5-power or on 18-power. I just checked it here at my desk, at 2400mm range the reticle covers far less than 1mm, possibly less than a quarter-millimeter (hard to be precise as it doesn't focus closer than 10yds) - the entire height of the reticle from crosshair to the post - 62 minutes at 4.5-power - covers about 50mm on a tape measure hanging on the door of my safe. On a snap shot at a fox at 20m the reticle covers 1.4mm of the fox, but is still heavy enough to pick up quickly. I have looked through scopes in the field with .14MoA reticles and they are far too fine for me to pick up against grass or trees, or anything other than white paper.

As you zoom in an FFP though, the reticle grows in size to conceal more of the target. Its angular dimensions don't change, but the coverage of the target does. Put your scope on a tape measure hanging at 20m and tell me what width the crosshair covers at minimum and maximum magnification, I'll try to remember to do it tomorrow myself, I don't think I've ever checked it under 100m. For me, FFP is the reverse of what you want, a heavy, easily-seen reticle at minimum magnification for snap shooting, and a finer reticle for precision at longer ranges.
focal_plane_debate.jpg
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I totally agree it's personal preference. FFP costs a premium though, so it's well worth determining that it is what you require before lashing out the funds.
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Re: FFP Vs SFP for Target shooting

Post by wannabustbunnies » 08 Dec 2019, 1:09 am

Your reticle can't stay the same thickness regardless of magnification with a SFP scope because of where the reticle is physically located in the scope. Your BDC subtensions change depending on your magnification as well which have pointed out previously so you can't have one without the other.
If your reticle is .25 MOA at 18x and you have a 4.5 X erector SFP scope everything changes by a value of 4.5x because you are only magnifying the image.
A FFP the reticle and image increase/decrease in relation to each other.
In your image above look at the reticle positions relative to the deer. The FFP stays the same whereas the SFP starts out wider than the deer and moves inwards as the power is increased.
Here is two sets of reticle subtensions from Sightron. Both 6-24 power scopes so 4x erector, one is FFP the other SFP.
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Last edited by wannabustbunnies on 08 Dec 2019, 1:18 am, edited 1 time in total.
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Re: FFP Vs SFP for Target shooting

Post by wannabustbunnies » 08 Dec 2019, 1:15 am

Good example of the reticle position relative to the target with the same reticle in both focal planes.
https://youtu.be/UuF8ZQR-DJ4
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Re: FFP Vs SFP for Target shooting

Post by Vicko » 20 May 2020, 8:18 pm

Just found this thread and I'm tossing up between FFP and SFP for my next scope at the moment too.. and I still haven't decided!

Two things I'll point out from the last few comments here.

Bladeracers image is a little misleading because it makes it look as though the reticle weights are pretty much the same at low magnification whereas the reverse is mostly true. FFPs only really suffer at low magnification because the reticle is TINY. From what I can gather - most FFP reticles are set to weight towards the upper end of magification, not the bottom.

Wannabustbunnies - I think Bladeracer was saying that the SFP reticle stays the same regardless of magnification 'in relation to the scope FOV'. Not the image. ;)
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Re: FFP Vs SFP for Target shooting

Post by Vicko » 20 May 2020, 8:28 pm

Oh and fwiw - I'm leaning towards an illuminated FFP. The illumination aspect should cater for the low magnification issue with reticle size.
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Re: FFP Vs SFP for Target shooting

Post by Aliqua » 20 May 2020, 9:42 pm

I recently went for a SFP for my first scope... for a couple of reasons. First was I didnt like the rectile line thickness increasing when I zoomed in at long range / small target. Eg - I might not have been able to 'see' the small centres of target at 22+ power on an FFP but on the SFP the rectile doesnt change in size (with the intention if long distant shooting).

2nd was the price. I felt that I was able to get better glass and more power (zoom) in SFP than FFP within my budget.

Whichever you choose they have their own pros and cons of which you will learn. They both have maths attached but from what I've been told in similar queries once you learn it, it becomes second nature.

With SFP if you know the size of your target you can use the moa/mil lines to calculate the distance quite quickly with experience.

Best of luck with your endeavour!
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Re: FFP Vs SFP for Target shooting

Post by straightshooter » 21 May 2020, 7:55 am

Much of the discussion of FFP and SFP reticles seems to be based on a misapplied understanding of the various functions of a rifle scope. No doubt fuelled by an uncritical acceptance of advertising propaganda which always works when it hits the right button.
For sensible discussion some things must be clearly understood.
With FFP the reticle stays a constant size relative to the target image at all magnifications. Put another way, it subtends a constant dimension (or MOA) covering the target. To say the reticle gets bigger at larger magnifications is an error of fact and indicates one has succumbed to an advertising (if not optical) illusion .
With SFP the reticle is not subject to magnification so it appears constant irrespective of magnification. Put another way, it subtends a varying dimension (or MOA) covering the target.
One of the real advantages of FFP is rarely touted because it is probably too difficult for a typical advertising target to comprehend.
Look at the cross section diagram of a scope put up by bladeracer and note the difference in physical distance of either reticle the user's eye.
It should be immediately apparent the advantage FFP confers is a reduced susceptibility to inaccuracy due to minor variations in the shooter's eye position.
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Re: FFP Vs SFP for Target shooting

Post by TassieTiger » 21 May 2020, 1:36 pm

^^^^ as a person who has just been through a saga with paralaxx / broken scope - I cannot emphasise enough how important this Point has become to me...
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Re: FFP Vs SFP for Target shooting

Post by Vicko » 21 May 2020, 2:42 pm

Straightshooter - it might be semantics, but a FFP reticle does indeed get bigger at larger magnification.
As it's staying constant with the target image it has to... both the target image and the reticle get bigger at larger magnification.

FFP - the reticle stays constant with the target image, both of which grow larger as magnification increases and FOV decreases.
SFP - the reticle stays constant with the FOV through the scope, so only the target image grows larger as magnification increases.

Thats an excellent point regarding the physical distance to the shooters eye and one I admit I had not even considered how paralax would be affected. Thankyou!

I take it that you're a FFP fan - do you use them across hunting AND target work?
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