The Beginner’s Guide to Scopes and Optics, 2019 Edition
We received a generous contribution from Josh Montgomery, author and founder of “Minuteman Review”.
He wrote a general guide for beginners on how to choose a scope.
In order to choose the top quality scopes, I (Mari) have added couple of comments to his article in orange.
Thanks Josh for writing for us and for the enthusiastic shooters just beginning.
(Thankfully we are receiving many inquiries. However as being shorthanded,
reluctantly we are not accepting third party contribution article at this moment.
We will notify on our website where there is a change. Thank you.)
The Beginner’s Guide to Scopes and Optics, 2019 Edition
Purchasing your first scope can be confusing. It can feel like there’s so much to learn,
that there’s no way to sort out which is the best scope for you.
But, choosing an optic isn’t as complicated as it seems. If you understand a few important things,
you can look at any scope and quickly determine whether or not it will work for you.
That’s what we’re going to cover here: the things that will enable you to assess any optic.
Note: We’re not going to cover the stuff that you can learn by reading your manual, like what the windage and elevation knobs do.
We’re going to help you understand what all these numbers on the package mean.
When you get a scope or check them out online, they’re usually labeled with a number like this: 3-9×40.
Let’s break that down one number at a time. There are 6 items to consider.
The first numbers in the specifications, “3-9x,” is the magnification (power).
Magnification is just how much larger an object will appear when viewed through the scope.
Magnification can be set at just about anything.
And, a common mistake that new shooters make is assuming they need the highest magnification possible.
Because bigger is better, right? That’s not always the case.
There’s a reason they make scopes with low magnification powers.
Choose the power of your scope based on how far you plan to shoot.
Size of your target matters as well but here’s a general guide for how much magnification you need:
0-200 yards: 1-6x magnification.
100-400 yards: 2-10x magnification.
300-700 yards: 4-25x magnification.
600-1000 yards: 10-80x magnification.
Now, there’s some wiggle room here.
As I’ve mentioned above, you need to take in account of the size of your target.
If you’re shooting targets the size of a dime at 200 yards, you’ll need more magnification just to see the target.
However, you can get away with lower magnification at longer ranges if your target has a lot of room for error.
But, avoid using a fixed 52x scope for something like shooting deer at 150 yards.
Using too much magnification for the distance and target size makes it difficult to get a stable sight picture.
We (manufacturer of March Scopes) talk to our customers all the time.
As Josh mentioned above, we came to comprehend that shooters choose the magnification according to
2 elements: distance and the target size.
For general 100 yard shooting competitions, many use 25x – 32x.
They don’t use higher magnification as it is hard to find the target with it.
Also you can see the mirage easier with a higher power and you might not like that when shooting.
On the other hand Benchrest shooting at 100 yard where the target is very small, 40x-50x are used.
Now with Field Target shooting, even though the distance is 15m – 50m,
Field Target shooters like to shoot at 80x.
For Service Rifle competitions, shooters shoot at 500m and 600m using 4.5x which is a low magnification.
Therefore for some competitions they won’t fall into the category above.
Please remember to always take in account of both distance and your target size.
(2) Objective lens diameter
The number after the “x” (=power) in the spec line is the objective lens diameter.
In a 3-9×40 scope, the objective lens is 40mm in diameter.
The objective lens diameter is always measured in millimeters.
A larger objective lens will collect more light and produce a brighter image when you look through the scope.
This is one of those cases where bigger is almost always better. In almost all cases, a brighter, clearer image is better.
The downside to a huge objective lens is that it makes your scope really bulky.
This may not seem like a big deal, until you try to hike when hunting with your rifle or shoot without a shooting bench.
Then you realize that those huge scopes make a rifle really difficult to handle.
So, you want the largest objective lens that you can get, without turning your rifle into a boat anchor.
The goal is to get a scope with a large enough objective lens to generate a clear image in your typical light conditions,
without turning your rifle into an unmanageable behemoth.
The size of the Objective lens is determined by the magnification of the scope.
When the magnification increases, exit pupil (bright circle centered in the ocular lens) becomes smaller.
That’s why we need to enlarge the objective lens in order to amplify the exit pupil.
For example at 80x, exit pupil is 0.7mm even with a 56mm objective lens.
When the magnification increases, the exit pupil decreases.
We increase the size of the objective lens when we want to enlarge the exit pupil.
(However there is a limit to optics according to maginification)
Here’s a guide for objective lens sizes of March Scopes:
(For some models we have different sizes of objective lens even for same magnification.)
(3) Lens coatings
The lens coatings enhance the performance of the lenses.
Good lens coatings will improve light transmission and color fidelity, in addition to adding durability.
There are four types of lens coatings:
- 1. Coated lenses have a single layer of coating on one lens surface.
- 2. Fully coated lenses have a single layer of coating on all air-to-glass surfaces.
- 3. Multi-coated lenses have multiple layers of coating on one lens surface.
- 4. Fully multi-coated lenses have multiple layers of coatings on all air-to-glass surfaces.
Clearly, the more layers and surfaces that are coated, the more expensive the lenses will be to produce.
Therefore, the scope will cost more for the buyer. This is true.
However, technology has advanced to the point where even budget scopes are equipped with fully multi-coated lenses.
There’s really no reason to settle for any other level of lens coating. Always opt for fully multi-coated lenses.
As Josh mentioned, almost all the scopes nowadays state that they use multi-coating.
More than a single layer (even for 2 layers) of coating will be called multi-coating.
However sometimes even if it is stated as fully multi-coated lens, they may be only painted
like the color of multi-coating (greenish color) and the transmittance may not be what you have expected.
You need to have a discerning eye for lens coating.
By applying multiple layers, reflection can be reduced and the transmittance can be increased.
Generally, the light transmittance will be ;
One lens surface without a coat : 96%
Single layer of coating : 98.5%
Fully multi-coated (more than 2 layers) lens : 99.5%
When transmitting 10 layers, light transmittance will be ;
One lens surface without a coat : （0.96）10＝66％
Single layer of coating : （0.985）10 ＝86％
Fully multi-coated lens (more than 2 layers) : （0.995）10 ＝95％
If we use a multi coat with the transmittance of 99.5% as in above for general coating,
when we calculate by the 20th power of 99.5%, the transmittance will be 89.5%. （0.995）20 ＝0.895％
That’s why we use only the top quality multi – coating whose transmittance is extremely near 100%.
We also try to present the color to be close to nature.
This is one of the most important aspects of any rifle optic. The clearer the lens, the clearer the image.
Unfortunately, it’s also one of the most difficult parts of a scope to assess.
Most companies have their own proprietary lens technology that they claim produces the clearest lens ever.
And, it’s tough to find out how clear the lens is, even if you can look through the scope in the store.
Most stores just don’t have bright enough light or enough space to assess glass clarity.
But, we do know one thing: you get what you pay for.
The lenses are one of the most expensive components to produce.
So, many companies skimp on lens quality to keep prices down.
It might feel unscientific, but the price is generally your best indicator of glass quality.
More expensive scopes and optics will be fitted with clearer lenses.
That’s true Josh, lens is one of the most important element to consider when choosing a scope.
March Scopes adopt ED lens.
ED stands for Extra-low Dispersion.
ED lens disperses light less than ordinary lens and reduces chromatic aberration.
Chromatic aberration normally appears when you are looking at a white object such as a white swan.
There will be a color blur at the border line between the white object and the background.
To reduce chromatic aberration, we incorporate ED lens for most of our scopes though they are more expensive than ordinary lens.
Except for March scopes with 24mm objective lens. These are scopes with lower magnification.
When at lower magnification, it is harder to find a chromatic aberration.
As there is hardly any difference in chromatic aberration between ED lens and normal lens when it comes to scopes with 24mm objective lens.
That is why we use normal lens for scopes with 24mm objective lens.
In 2017 we started adopting Super ED lens for High Master model March Scopes.
Incredible Super ED lens formula which is closer to fluorite than ED lens for superior correction of chromatic aberration.
The resulting sight picture provides unsurpassed edge to edge definition
and renders color in true-to-life hues across the entire field of view.
We have even adopted Temperature Anti-Drift Lens System in 2019 as well.
In the latest optical systems for automotive cameras, a new lens material has been developed
to accommodate changes in environmental temperature by altering the refractive index of the lenses.
This new lens material has been adopted for the new High Master model March Scopes to create a more stable lens system that naturally adapts to changes in temperature to maintain focus and clarity over a wide range of conditions.
We try to adopt the best glass ever searching even outside the optics industry.
We only use top quality Japanese lens so we can inspect their factory occasionally. That is how serious we are.
(5) Parallax adjustment
Parallax itself is pretty complex, and would require many pages to explain fully.
But, the short explanation for the sake of this article is that a scope with an adjustable parallax distance
is better than a scope with a fixed parallax distance.
If you can adjust your parallax range to match the range of your target, your reticle will move less in relation to your target.
That means it’s easier to stabilize your reticle for an accurate shot.
Yes, you can make accurate shots with fixed parallax.
That’s why many budget scopes use fixed parallax.
However, it’s much easier to get a high degree of precision if your scope offers adjustable parallax.
If you are a precision shooter, you will need to adjust the parallax precisely. We recommend that you use an adjustable parallax.
On the other hand if you are a beginner and do not know how to adjust the parallax,
if you set the focus at a wrong distance there is a risk of increasing the parallax.
We recommend that you use a scope lower than 10x with fixed parallax.
(6) FFP or SFP
Can I add another characteristic Josh?
We get a lot of questions concerning whether to choose FFP or SFP.
For FFP-First Focal Plane reticle, when you change the magnification,
the target and the reticle will zoom in and out collectively.
The reticle line will be fine at lower magnification and thicker at higher magnification.
The point of aim (POA) does not change throughout the entire zoom range.
This reticle is suitable for hunting as the scale value will always be consistent regardless of the magnification.
On the other hand, the thickness of the SFP-Second Focal Plane reticle is always constant
and only the target image will be zoom in and out according to the magnification.
Scale value of the reticle is designed at the specific magnification.
This means that you will need to convert the scale value at other magnification.
The advantage of the Second focal plane reticle is that you have a thick and easy to see reticle even at the lowest magnification.
Therefore this reticle is suited for precision shooting.
Please choose the reticle according to your preference.
That’s it. If you check these 6 characteristics, you should be able to get a scope that matches your needs every time.
There are other things that affect performance.
But, they’re largely standardized, and there’s very little variation between scopes.
So, check out some of the Scopes, and use this guide to help you decide which one will work best for you.
Written by : Josh Montgomery, author and founder of “Minuteman Review” http://www.minutemanreview.com
Notes added in orange by : Mari Morita