Prism Scope Field of View
- Thread starter stanley_white
- Start date
Are you comparing a LPVO on 1x to a 1x Prism or a 3x etc.
I think on the same magnification, they are similar.
I think on the same magnification, they are similar.
Yes.
I know they aren’t, I am wondering why.
Examples:
At 1x the FOV of a Trijicon Accupoint 1-6x is 117.5 feet at 100 yards.
At 1x the FOV of a Primary Arms GLX is 74.8 feet at 100 yards.
At 1.5x the FOV of a Trijicon ACOG 1.5x16mm is 39 feet at 100 yards.
-Stan
Objective lenses are all different sizes. That accounts for a good bit of FOV differences. Internal lens array will sort a bit too.
The 4x acog has a fov of 36 feet at 100 yards which is more than most scopes at 4x.
I don't think this is a problem with prisms, I'm sure ilya will see this thread and chime in with some facts.
I don't think this is a problem with prisms, I'm sure ilya will see this thread and chime in with some facts.
Just like regular scopes they can be designed in different ways, for different purposes.
The Burris RT3 and Swampfox Trihawk are both 3x prisms, the RT3 has a 38ft FOV, the Trihawk 52ft.
The RT3 is half the weight, much smaller and has longer eye relief.
They if you look at the Trijicon 3x30, that thing has a small FOV, is huge, weighs a tonne, and has a very short eye relief.
Which I'm guessing is just due to it being a much older design, and technology has moved on a lot since then.
The Burris RT3 and Swampfox Trihawk are both 3x prisms, the RT3 has a 38ft FOV, the Trihawk 52ft.
The RT3 is half the weight, much smaller and has longer eye relief.
They if you look at the Trijicon 3x30, that thing has a small FOV, is huge, weighs a tonne, and has a very short eye relief.
Which I'm guessing is just due to it being a much older design, and technology has moved on a lot since then.
As has been mentioned, not all prisms do have significantly less field of view.
The 4x ACOG and Elcan Specter have huge fields of view compare to LPVOs. And some LPVOs have tiny fields of view.
It’s all about the optic design.
FOV is dictated by the eye piece design. Lens diameter, eye relief, Focal length are the main drivers of eyepiece FOV, otherwise known as AFOV.
All else being equal the following is true-
-Larger Diameter eyepiece lens, wider FOV (For example the new Kahles/Swaro 28 degree scopes)
-Longer eye relief, narrower FOV
-longer focal length, narrower FOV
1X Prism scopes tend to have relatively small diameter eyepiece
Acog's have smaller eyepieces than LPVO's, BUT that have significantly shorter eye relief. The short eye relief is where that get the wide FOV.
All else being equal the following is true-
-Larger Diameter eyepiece lens, wider FOV (For example the new Kahles/Swaro 28 degree scopes)
-Longer eye relief, narrower FOV
-longer focal length, narrower FOV
1X Prism scopes tend to have relatively small diameter eyepiece
Acog's have smaller eyepieces than LPVO's, BUT that have significantly shorter eye relief. The short eye relief is where that get the wide FOV.
Thank you.
It is still interesting that the widest FOV ACOG, the 1.5x16mm, is 39 feet at 100 yards, while the Trijicon Accupoint 1-6x, is 117.5 feet at 100 yards at 1x.
Barring the magnification differences between 1.5x and 1x the FOV differences are still quite large.
-Stan
When you account for magnification, the widest FOV ACOG is the 4x, at 36.8’. That would be 147’ if it were 1x. Only the Kahles 1-8v2 would beat that.
Thank you.
Accounting for magnification then, what are the numbers of the 1x as compared to the 1.5x that I described above?
I am not a Mathlete.
-Stan
people malign the Specter, but any LPVO I’ve ever used especially say the ATACR is like looking through a goddamn straw in comparison. On 1x I can see the switches on my handguard lol.
Background that I didn’t add, I loves me some Leupold MK5 5-25x, which is decried by many as “looking through a soda straw.”
I bought the 1.5x ACOG, wow, if the MK5 is a soda straw the ACOG is a coffee stirrer. The ACOG was returned within minutes of unboxing.
I then bought three of the Trijicon Accupoint 1-6x, and they are great, though my prism curiosity persists.
-Stan
It’s not exact, because sometimes the angular field of view isn’t linear across the magnification range. But close enough for rough comparisons, you just multiply the FOV by the magnfication amount. So 39 * 1.5 = 58.5 feet at 100 yards. Which is indeed bad.
Sure thing. It makes it handy for quick comparisons rather than digging up the actual angular measurements.
Like the Mk 5-25, if it were a 1x, would have a FOV of 102 ft at 100 yards. Not great, not bad. Better than the 1-8 Nightforces.
I ran an OS4x for quite some time and I'd have to agree, the image/glass/reticle was phenomenal. And to be fair, the NF lpvos (even the ATACR) while quality optics comparatively lack the optical forgiveness of some of their LPVO peers, but the point is still valid.
That said, the issues most have with the Elcans are either with the shitty ARMs clamping hardware and their all too often feeble clamping on rails. Or the distrust of the prisim switching mechanism and potential zero shift.
