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35 mm tube IOR's

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Unread 11-22-2003, 07:20 PM
Bronze Member
Join Date: Dec 2002
Location: FL
Posts: 45
Re: 35 mm tube IOR\'s

gen2 Premier reticles are first focal plane and so is S&B.Nigthtforce is second focal plane and this is the first time i hear something else.. [img]images/icons/confused.gif[/img]
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Unread 11-22-2003, 08:58 PM
Junior Member
Join Date: Oct 2003
Posts: 13
Re: 35 mm tube IOR\'s

It's only confusing because somehow, somewhere you, and others have received wrong information.

Magnification of the reticule can be done at two places.
In the front, which is referred to as the First Focal Plane.
In the rear at the occular assembly, which is referred to as the Second Focal Plane.

Brent, your NF R2 does grow in size as the target grows. Now, because they BOTH grow at the same time, in the same proportion, appears that they don't.
Easiest way to examine (test)this is a side by side comparison of a Leupold, Nikon, Burris, many IOR's, Tasco, Simmons, Zeiss Conquest, and many many more, which almost all of them are Second Focal Plane.

At the lowest power, look at something white.
When you increase the magnification, the target grows, but the reticule gets smaller.
In reality, it stays the same size, but the target is growing.

Now, do exactly the same thing with your Night Force. Sometimes it's easier to look at a blank wall. The lines will NOT get smaller. That's First Focal Plane in action.

i don't wish to antagonize other posters, but by explaining correctly how things really are, some will get upset.
Bear in mind my wish is to easily explain away some misconceptions that have been around for a while, so we all can shoot better, and have more fun.

Calibrations are all set, no matter who make the optics. Physics, and math don't change.

Try the 'comparison' first, then we can get to the reasons for subtension changes.

But first I'm going to throw a stink bomb in the fire.
I'll bet that 98% of the readers & posters, and shooters in general don't properly adjust a scope.
There is one and only one way.

[ 11-23-2003: Message edited by: Guns & Glass ]
Happy Bullet Holes!
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Unread 11-23-2003, 01:52 PM
Platinum Member
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: 35 mm tube IOR\'s

Originally posted by Magnumdude:
In the first focal plane the reticle subtends the same proportion of the target no matter the power. In a 2nd focal plane, the reticle will subtend proportionately less of the target as you increase the scope magnification.

That's what I'm saying exactly.

Another note:
When I check the box in my Exbal program marked "Reticle Located in 2nd Plane", I can then modify the tic calibration by changing the power setting.

Also, if it's checked, and my drop is 13.6 MOA at the target, I can hit the "optimize power" button and it will tell me what power setting to use with what tic mark to be dead on.

Describe the adjustment procedure you recommend, if you will. [img]images/icons/smile.gif[/img]

I'll call Jeff at NF Monday and see what his definition of first and second plane is too.
Brent Moffitt
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Unread 11-23-2003, 02:51 PM
Junior Member
Join Date: Oct 2003
Posts: 13
Re: 35 mm tube IOR\'s

Do you have an owners manual for your NF?
Do you have the special sheets (not part of the manual) made to explain the RR, and R2?
If not I'll email then to you.

Your post on 11/22 @ 4;45
"My reticle does NOT change with any power change peroid. Every place I've read about 1st & 2nd focal planes, this is defined as a reticle in the 2nd focal plane".

The first sentence IS correct.
Perhaps you meant," that is defined as a reticle in the 1st focal plane".
If so, then you are correct.
The examples are what's off.

regarding focal planes, I'll dig in my tech books for something I might either post, or pix I can email anyone who wants to learn.

Regarding proper adjustment, it will help greatly if you will describe the method-procedure you use. It gives me a reference point.
Happy Bullet Holes!
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Unread 11-23-2003, 03:46 PM
Platinum Member
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: 35 mm tube IOR\'s

I've got the manuals, and most all the spec sheets I've seen on them.

I think we're talking about the same thing, and agree that the NF scopes power setting changes the tic spacing in relation to the target image, only you are just defining this as a reticle in the 1st focal plane, where everyone else defines this as a 2nd focal plane reticle, correct?

What I was meaning to say in the post you quoted was just that, the reticle does not get visibly larger to the eye, but it does get larger in relation to the "Target" if going from 22x down to 11x, subtension is now 4 MOA between tics, not 2 MOA as they are at 22x. This has always been defined as a reticle in the 2nd focal plane.

The Springfield Armory scopes my dad has for instance, they are the eact opposite of this and are what I've always understood to be 1st focal plane reticles. The mildots in the SA scopes retain the 1 mil spacing no matter what power you select, unlike the NF scopes.

The only time the reticle in the NF scopes get visably larger is when the power level is turned "down", and you're looking through the scope through the "objective" back to the ocular lense.
The SA scopes reticle do not change size at all when doing looking through them backwards.

I used to put a white piece of paper behind the ocular lens and look back through the objective lens to line up my chronoghraph screens, setting it at 5.5x, the reticle was as large as possible. I did this until Ian suggested I use a laser to set up, thanks again Ian [img]images/icons/smile.gif[/img]


When I adjust the eyepiece, I do it at 200 or 300 yards after I eliminate the parallax, then I focus the reticle.

Is it different for 1st and 2nd focal plane reticles? Am I doing it wrong too?
Brent Moffitt
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Unread 11-23-2003, 04:25 PM
Junior Member
Join Date: Oct 2003
Posts: 13
Re: 35 mm tube IOR\'s

Confess I don't know how to put pix that show scope interiors, drawings, and reticles on this site.

Go to Schmidt & Bender home site.
Click on 'Details'. There is a great set of comparison pix of both planes.

Will try to answer following your paragraph-sentences.

Have the NF seperate sheet on Illuminated NP-R2 Reticle. has a thick black border, with NIGHTFORCE in red letters, and a red line in the black border. Has a white circle with the R2 shown on front side, and the Ranging & BDC on the back.
If not give me your email, and I'll send it.

Calibrations always change as magnification changes.
The accuracy is much, much greater in the 1 st focal plane.
The growing/shrinking of BOTH the target AND reticle only occurs in the 1st focal plane. In the second reticle always stays the same, but the target can grow or shrink.
Ie, when the power is increased the reticle gets smaller.
See the Schmidt & Bender web site.

Springfield Armory (don't ask me what I think of them, because I just told you)is a 2nd focal plane system. They copied, actuall violated a patent of Dan Shepherds great system. they made his first model scopes, were so bad it almost put him out of business. New company is one of the best optic makers in Japan. Great stuff.
Dan could have sued them, but the cost to do it would only have paid for the attorneys. he wouldn't have gotten a dime.

Before I answer your last sentance, please answer my questions.
? #1.Every you look at both the reticle AND the target, at the SAME time,...are they BOTH sharp AND clear.
? #2. When you put the reticle on the target, are they BOTH sharp and clear at the SAME time?
? #3. If you need to adjust the scope to one or the other sharp & clear, what do you use to adjust?
Happy Bullet Holes!
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Unread 11-23-2003, 06:42 PM
Silver Member
Join Date: Aug 2002
Location: Southern Illinois
Posts: 245
Re: 35 mm tube IOR\'s

Guns & Glass

Could you e-mail me please?

Ralph Jones

I have a question regarding optics, and it is fairly urgent.
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