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As a corollary to this, and assuming I really do follow this...

If a SFP scope is set to range at 10x and a 36" target reads 2.0 mils, then the target is 500yds away.

If you change the magnification on that scope to 5x and range the same target, it will only appear as 1.0 mils.

If you change the magnification on that scope to 15x and range the same target, it will appear as 3.0 mils.

If all this is correct, then it should be possible to range at different powers as long as you compensate for the magnification.
 

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I will openly admit I haven't (yet) noodled through all the posts here.... so with that caveat and asking this group's indulgence, let me ask this--->

OK... a Mil-dot reticle allows for reasonable range estimation, per Mels formula, the formulas shown on this thread, and the good Cheaper-Than-Dirt article.

A big convenience is the use of variable power scopes, in that you can dial-up/down the power to get the "object" to subtend a reasonable mil-dot resolution...so you can go from there and use these formulas.... OK, I think I got *that*...

However, .. is it correct to say that this range estimation can also be done with a fixed-power Mil-Dot scope?, .. with the only disadvantage being that sometimes the target object will be too small to make accurate size assessments because one can't resolve size well-enough in-between mil-dots at a fixed ( High ! ) power? Meaning, this issue can be helped by a variable power scope where you can get a finer-cut on your object-size estimate ( and therefore be more accurate with the formulas that will be used)?

Does that make sense?.... thanks.
 

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A second focal plane scope can only be used to estimate range at a single power (which can vary with the maker) unless you use some kind of factoring. A fixed power scope is the same as a second focal plane scope that is adjusted to it's correct power.

Does that answer your question?
 

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It partially answers the question...namely.... "yes, a fixed power scope works as it will be the same as noting the single-power within a variable's range, where it is calibrated and therefore accurate."

The other part of the question is this--> a variable works such that ( for example), you adjust the variable such that the mil-dot subtends a "man's" height at the range you view ( 72" tall, say ~20 mils)....and thru noodling some numbers, look back up on the scope, see the magnification ...apply some math with this magnification...and thereby establish range. Aka "Mel's method", I gather..although I can't seem to find the original sticky.

The variable power allows a reasonable fine cut on guessing a guy's size and having him fit between 20 mils. At higher power, your "guess" as to the guy's size will be more limited...because the man may subtend only 1/5 or 1/4 or 1/3 the distance between any 2 mildots...making for greater "reading" errror.

Another way of saying this--> yes, a fixed power "works"...but is "in-practice" harder to apply because of the higher-fixed power (only) that is being used.

Am I saying ( seeing this) correctly ??? Or am I missing something fundamentally? Thanks for your patience.
 

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Nevermind... I am an idiot.....

Here is a direct quote from (apparently) Mel's review of the Weaver Tactical scope ( 3x9, Tactical Grand Slam, 3-10X/40mm, Mil/Mil)--->

"The scope has a traditional mildot reticle of wire construction and according the detailed diagram that came with the scope, it has .25 MIL diameter dots which would be the USMC dots, though they are round and not football shaped. All of the dimensions are the typical standard mildot dimensions and since it is a second focal plane scope, the mildots are only accurate at one power, 10x in this case. This does allow the clever little trick of zooming in on a 2 yard tall target, such as a 6' tall man, until 2 MILs covers that target, then look at the power ring and that is the range to the target in hundreds of yards. This is a quick and dirty method of range estimation that works fairly well. Of course, you can cover a 1 yard size target with 1 mil and do the same thing.."

Simply....without a "zoom" capability...then *this* method is not possible with a fixed power scope.

Carry on guys...sorry for the confusion....
 

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IPSC said:
Carry on guys...sorry for the confusion....
Been there. Done that. Have the t-shirt. Several in fact.
 
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