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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 6/12/2005 10:14:32 PM EDT
Every once in a while this question comes up (and I wanted an excuse to post some pics from my new camera) so...

In the below pictures, the illuminated reticle of the EOtech is in the first focal plane while the diamond crosshair reticle of the scope itself is in the second focal plane. Because the EOtech reticle is in the first focal plane it is always the same size relative to the image being viewed, which means that its size will change as magnification is changed. The diamond crosshairs are in the second focal plane so they always the same size, regardless of magnification which means that they become smaller relative to the viewed image as magnification is increased. Don't mind the actual view, I was just trying to get the reticles and it is really hard to get the camera into right position behind the scope.

At 1.5x magnification:


At 5x magnification:


And here's the high-speed setup I used for the pics:
Link Posted: 6/13/2005 6:35:06 AM EDT
Great post!

BTW, how are you liking that Simmons scope?
Link Posted: 6/13/2005 8:13:31 AM EDT
The scope just came in the mail last week and I haven't taken it to the range but so far it seems like a decent scope. So long as it'll take and hold a zero once I get it to the range I'll be more than happy and it only cost me $50 from CDNN. Can't beat that.
Link Posted: 6/13/2005 9:43:15 AM EDT
Link Posted: 6/13/2005 11:02:47 AM EDT

Originally Posted By Ridge:


I'm not sure what you're trying to say...
Link Posted: 6/13/2005 11:07:24 AM EDT

Originally Posted By Hoplophile:

Originally Posted By Ridge:


I'm not sure what you're trying to say...



Me neither

But thanks for posting this. It's something I never quite knew about.

WIZZO
Link Posted: 6/13/2005 11:17:28 AM EDT

Originally Posted By WIZZO_ARAKM14:

Originally Posted By Hoplophile:

Originally Posted By Ridge:


I'm not sure what you're trying to say...



Me neither

But thanks for posting this. It's something I never quite knew about.

WIZZO




Seems to me that was the short way of him saying "Thanks for the explanation. The lightbulb above my head has been illuminated due to your informative post."

Nothing mean about it.
Link Posted: 6/13/2005 12:51:08 PM EDT

Originally Posted By PosterChild:
Seems to me that was the short way of him saying "Thanks for the explanation. The lightbulb above my head has been illuminated due to your informative post."

Nothing mean about it.


Not assuming anything, just wasn't sure what he meant.
Link Posted: 6/13/2005 12:56:44 PM EDT
Is that the Simmons 1.5-5x20?
Link Posted: 6/13/2005 1:10:20 PM EDT

Originally Posted By Lancelot:
Is that the Simmons 1.5-5x20?

yep.
Link Posted: 6/13/2005 1:42:37 PM EDT
[Last Edit: 6/13/2005 1:45:59 PM EDT by Ridge]

Originally Posted By PosterChild:

Originally Posted By WIZZO_ARAKM14:

Originally Posted By Hoplophile:

Originally Posted By Ridge:


I'm not sure what you're trying to say...



Me neither

But thanks for posting this. It's something I never quite knew about.

WIZZO




Seems to me that was the short way of him saying "Thanks for the explanation. The lightbulb above my head has been illuminated due to your informative post."

Nothing mean about it.



Sorry about that. You got it PosterChild. A good series of pictures can say a thousand words.

I also had an epiphany about a possible sight combination.

Edit: I've been looking at that little icon, it does have a little smart ass look to it doesn't it. I just meant it as enlightenment, sorry again.
Link Posted: 6/13/2005 1:52:14 PM EDT
[Last Edit: 6/13/2005 1:58:12 PM EDT by brewsky101]

Originally Posted By Hoplophile:
The scope just came in the mail last week and I haven't taken it to the range but so far it seems like a decent scope. So long as it'll take and hold a zero once I get it to the range I'll be more than happy and it only cost me $50 from CDNN. Can't beat that.



The adjustments are a bit crude (1click=1"@100yards), otherwise this scope seems to be a very decent alternative to other offerings (at least until someone produces a variable mag. optic with true 1x and BAC capable reticle [cough]Mueller[/cough]). I'm sure the glass isn't on par with Leupold or S&B but at such low magnification it's realy a moot point.
Link Posted: 6/13/2005 1:53:23 PM EDT
I aplogize for seeming like I jumped on you. I just didn't know what the icon meant in this case.

WIZZO
Link Posted: 6/13/2005 2:53:55 PM EDT

Originally Posted By Ridge:
I also had an epiphany about a possible sight combination.


No sweat Ridge, just wasn't sure what you were saying and was trying not to assume.

A few notes about the setup shown above:

- It's rather heavy having two full size optics and I don't think I'd ever choose to use it this way.
- The Simmons needs to be an inch or so farther forward than it is in the pic. I just slapped it together to play around with. The Simmons is going along with some other parts onto a plinking/fun rifle I'm throwing together and the EOtech is what is normally on that rifle.
- Having played around with putting a red dot in front of a normal scope before I can say that it works less well as magnification increases.
- There is a good deal of parrallax. I did my best to take pics that kept the two aligned but when you look through it the two reticles do not stay aligned unless you have your head perfectly positioned. (Hmmm, maybe that in itself could be a tool...)
- Using the EOtech with the large window with a scope with such a small objective is a best case scenario. Using an Aimpoint and/or a larger reticle darkens the image noticably. After all you are still 'seeing' the light refelcted from the edges of the dot optic but they are very far out of focus so instead of actually seeing the Aimpoint you get 'dark' light mixed throughout the image.
Link Posted: 6/13/2005 5:57:59 PM EDT
Hoplophile,

What kind of mount is that on the Simmons Scope?
Link Posted: 6/13/2005 6:04:11 PM EDT

Originally Posted By scromer:
Hoplophile,

What kind of mount is that on the Simmons Scope?

RRA
Link Posted: 6/13/2005 6:47:22 PM EDT

Originally Posted By Hoplophile:

Originally Posted By Ridge:
I also had an epiphany about a possible sight combination.


No sweat Ridge, just wasn't sure what you were saying and was trying not to assume.

A few notes about the setup shown above:

- It's rather heavy having two full size optics and I don't think I'd ever choose to use it this way.
- The Simmons needs to be an inch or so farther forward than it is in the pic. I just slapped it together to play around with. The Simmons is going along with some other parts onto a plinking/fun rifle I'm throwing together and the EOtech is what is normally on that rifle.
- Having played around with putting a red dot in front of a normal scope before I can say that it works less well as magnification increases.
- There is a good deal of parrallax. I did my best to take pics that kept the two aligned but when you look through it the two reticles do not stay aligned unless you have your head perfectly positioned. (Hmmm, maybe that in itself could be a tool...)
- Using the EOtech with the large window with a scope with such a small objective is a best case scenario. Using an Aimpoint and/or a larger reticle darkens the image noticably. After all you are still 'seeing' the light refelcted from the edges of the dot optic but they are very far out of focus so instead of actually seeing the Aimpoint you get 'dark' light mixed throughout the image.



I didn't want to say it (probably totally stupid). I've seen setups like this before, people usually just playing around. But I was thinking when I saw your post how well a Jpoint or Dr optic might work either in front or behind the scope. You could even put the small optic on a QR mount and remove it when you didn't need it (or visa versa). A small light like that with a non illuminated scope would probably weigh less than an illuminated scope by itself. Course it was just an idea and probably has all of the problems you mention with the eotech, except maybe weight.
Link Posted: 6/13/2005 8:10:04 PM EDT

Originally Posted By Ridge:
But I was thinking when I saw your post how well a Jpoint or Dr optic might work either in front or behind the scope.



Hmmmm. Ya know....
Link Posted: 6/13/2005 8:28:04 PM EDT
Just an FYI: I think you'll be pretty pleased with the scope (even if it didn't cost $500 wholesale). I have a POS Simmons 4x32mm shotgun scope that I will never get rid of. The optics in it are pretty clear and bright for a low-end scope. The adjustments, though, leave something to be desired, and can make zeroing the thing kind of a PITA. Once you do get it zeroed though, it'll stay that way. Mine's been knocked around enough that I've refinished it 3 times, and it's still going strong.
Link Posted: 7/9/2005 11:34:36 AM EDT
Link Posted: 7/9/2005 12:13:42 PM EDT
Link Posted: 7/9/2005 3:07:46 PM EDT
Here's another set of pictures....

At low power
[ link to LARGER image ]

At med power
[ link to LARGER image ]

At high power
[ link to LARGER image ]

Note that the reticle demarcations always cover the same amount
of the target.
Link Posted: 7/9/2005 4:00:42 PM EDT
Zak, your posts are always helpful and informative and in many ways "state of the art".

I'd like your comments on one issue, for RAPID engagements of multiple targets at distances over 250 yards with the typical military calibers it seems that the FFP variable scope would hold a significant advantage since the field of view is adjustable without loss of the usefulness of the reticle demarcations for multiple zeros set for bullet drop and/or windage.

Now obviously, if we are dealing with semi concealed targets near maximum range say with an AR, greater magnification will be important for target identification, for instance a tree line at 650 yards, a SFP scope may be just as useful as a FFP, but for multiple exposed targets at 325 yards, the FFP scope would be better due to the fact that the FOV can be increased and the targets engaged more efficiently.

Is this as big of an advantage for the FFP scopes as it seems, and as your photos seem to suggest?


Edwin
Link Posted: 7/9/2005 5:44:25 PM EDT
edwin907,

As background, here are three other related threads:

'Which ACOG for SPR?"
"Ideal practical precision AR15 optic"
"TacPro sniper match report"

Besides 3Gun matches where we shoot AR15's out to 400 yards (which are the minority of 3Gun matches), rapid engagements of multiple targets beyond 250 yards occurs in two types of competition I've done: IPSC/USPSA "MOR" (Manually Operated Rifle) and the Tactical/Sniper matches.

Think of MOR as an IPSC stage, but generally on steel at long range. You might have a bunch of shooting positions/locations and an array of targets varying in direction/heading and distance to engage at each position. Your score is your hits divided by your overall time.

For the latter, Tactical/Sniper matches, the general drill is to locate, range, and engage a known number of targets in a time limit. For example, at TacPro, we had to range and engage 5 targets in 90 seconds or 2 minutes. At the ITRC, there is no per-stage time limit, but you and your partner have to finish a series of 10-12 stages in a gross time limit like 90 minutes. There, you have to locate, range, and engage the targets as quickly as possible.

Another aspect of both types matches (which applies moreso to real life encounters I imagine) is moving targets. A moving target requires more field of view to track in addition to reticle features to account for lead/trail (depending on if you are also moving or not).

To the general question- FFP Horus-style reticles are dominating MOR. They are doing well and even winning conventional sniper matches, but that depends more on the shooter than his equipment, as long as it does not impede him.

Like I wrote in the TacPro match report (link above), the Horus is real for multiple engagements. On an unknown-distance stage (timed), I ranged the targets with my LRF and noted the ranges, as I moved from target to target, I needed only look up the dope for that distance and hold-over in the reticle. On a stage where I knew the distances beforehand (325, 375, 500), I dialed to 375, and noted the hold-under for 325 (0.4mil), and the holdover (1.1mil). While shooting the stage, I merely used the appropriate hold-under/over points in the reticle.

The FFP comes into play because with a wide range variable scope (my SN3 is 3.2-17x), you need to dial down the power to widen the field of view. Target to target transition times are drastically improved by widening the field of view. And to keep that reticle working properly, it has to be on the FFP.

Another advantage of the FFP is that ranging and miss-spotting can be done at any power and yield direct accurate results.

If we're talking bolt rifles, then a reliable detachable magazine holding at least 10 rounds is pretty much mandatory for these "action" precision rifle events.


it seems that the FFP variable scope would hold a significant advantage since the field of view is adjustable without loss of the usefulness of the reticle demarcations for multiple zeros set for bullet drop and/or windage.

Exactly.


Now obviously, if we are dealing with semi concealed targets near maximum range say with an AR, greater magnification will be important for target identification, for instance a tree line at 650 yards, a SFP scope may be just as useful as a FFP,

Yes, in this regard, the scope is being used to aid target location and I.D. The efficacy will depend on the field of view at the same power and the optical clarity. I personally prefer to use a good set of binoculars since they generally offer a wider field of view than a riflescope and have the advantages of more (2x) optical information and binocular vision. I use a set of Leica 10x42 Ultravids. The new Geovids are just as good, though heavier and larger, but combine LRF capability.


Is this as big of an advantage for the FFP scopes as it seems, and as your photos seem to suggest?

If you are interested in shooting things far away, varying headings and distances, as quickly as possible, I think so. It will help to have a spotter to range targets for you, and you will want your dope for the locale memorized.

For the more conventional type of long range shooting where there aren't multiple target-distance engagements and there is a lot of time to set up (ie, dial), a regular old non-FFP scope with external knobs, even with a Duplex reticle, will work fine.

Hope this helps
Zak
Link Posted: 7/9/2005 5:50:37 PM EDT
[Last Edit: 7/9/2005 5:56:15 PM EDT by Zak-Smith]
One more thing I forgot to mention..

Ever notice how the exit pupil size numbers increase as the scope power is dialed down? That's the math behind the observation that a scope at a lower power will produce a brighter image than the same scope dialed up in power. During the day it doesn't make a difference. During the night, it makes a big difference in target ID and sight picture. And if you want your cool illuminated mil-dot/NPR2/Horus reticle to be useful, it better demarcate the same at the power you've dialied down to in order to see your target...

ETA:

The reticle pictured is the Horus H25. I have used it on my 308 bolt rifle to successfully engage targets as small at 7" square plates out to 650 yards, using only reticle hold-over. On something that small, that far away (ie, just over 1MOA target size), the speed advantage is slight if any, mainly because you're waiting for breath, heart rate, and other physiological "wobble" to converge in the correct sight picture. On anything larger or closer, it is much faster than dialing, and much more accurate than "Kentucky" hold-over.
Link Posted: 7/9/2005 6:29:42 PM EDT

Originally Posted By Zak-Smith:
Ever notice how the exit pupil size numbers increase as the scope power is dialed down? That's the math behind the observation that a scope at a lower power will produce a brighter image than the same scope dialed up in power. During the day it doesn't make a difference. During the night, it makes a big difference in target ID and sight picture. And if you want your cool illuminated mil-dot/NPR2/Horus reticle to be useful, it better demarcate the same at the power you've dialied down to in order to see your target...



Yes, that's sort of a slam dunk for the FFP scope for "tactical" use, and something I had failed to consider, it seems pretty obvious that the FFP scope had greater versatility, but the low light advantages hadn't even crossed my mind.

Many thanks, Zak, incredibly informative posts as usual.
Link Posted: 7/10/2005 6:14:45 AM EDT
Zak,

Great posts.

Now a great depiction of a 2nd plane reticle would be a varmint rig looking at a prarie dog. I don't have a picture, but if you could imagine being zoomed in at high magnification, the retcile subtends less than it did on low magnification. The benefit here is that more of the target is visible behind the reticle when zoomed in. The bad point is that ranging only works at one magnification level so you may be dialing up and down at times between ranging and shooting.

This probably is universally understood, but in case anyone wonders, the way you can tell if a scope is 1st or 2nd plane, 2nd plane scopes' specifications listed in mfg's catalogs/websites will provide two subtension values, one at min magnification and one at max magnification. If you see that, you know you're dealing with a 2nd plane scope. A 1st plane scope will not vary in subtension across it's magnification range.
Link Posted: 7/10/2005 8:14:56 AM EDT
FFP reticle scopes cannot have a shift in POA/POI when zoom changes which is not the case with second focal plane scopes. This is probably the most important reason the FFP reticle is selected by the manufacturer.
Link Posted: 7/10/2005 2:52:31 PM EDT
Second focal plane (Nightforce 5.5-22).

At 5.5x:
[ link to LARGER image ]

At 22x:
[ link to LARGER image ]

Note the size of the black tree trunk vs. the length demarcated by the mildots.
Link Posted: 8/28/2005 10:56:48 PM EDT
tag, good info.
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