When shopping for a new riflescope or spotting scope it’s easy to get confused by all the technical terminology. Do you wish you had a better way to compare scopes — beyond just size, weight, and price? Well Swarovski Optik can help. The Swarovski Hunting Blog offers a helpful guide to technical terms used when comparing scope specifications. Here are some important definitions, expressed in layman’s language:
Objective Lens Diameter
The objective lens diameter determines the size of the optical system’s entrance pupil. The bigger the objective lens diameter, the more light the system can capture. However, the size of the objective lens does not determine the size of the field of view.
Exit Pupil
The size of the Exit Pupil is determined by the objective lens diameter and the magnification. If you look at the eyepiece from a distance of around 30 cm (11.8 in), the Exit Pupil appears as a bright disc.
For calculating the Exit Pupil the formula is:
Exit Pupil = objective lens diameter ÷ magnification (expressed in power number).
The larger the Exit Pupil, the more light will reach the eye.
Field of View
The Field of View is the size of the circular section of the area which can be observed when you look through a long-range optical device. In the case of rifle scopes, it is specified at a distance of 100 meters or 100 yards. For example, 42.5 m at 100 m or 127.5″ at 100 yards. As an alternative, the Field of View can also be stated in degrees (e.g. 6.6°).
NOTE: The technically-feasible size for the Field of View is essentially determined by the magnification. The higher the magnification the smaller the Field of View.
Twilight Factor
The Twilight Factor defines the optical system’s performance in poor light. The statement “the greater the twilight factor, the better the suitability for twilight” only applies if the exit pupil is larger than or at least as big as the eye’s pupil. The pupil in the human eye can only open to around 8 mm. As we get older, our eyes become less flexible, which limits our ability to see things in twilight or at night. Therefore [an optic’s] exit pupil cannot always be fully utilized.
For calculating the Twilight Factor the formula is:
Twilight Factor = root of ( magnification x objective lens diameter ).
NOTE: Spotting scopes have extremely high twilight factors because of their high magnification and large objective lens diameter. But [when used at high magnification] their small exit pupil can make them [somewhat difficult] to use in twilight.
MIL-system scopes are popular with tactical shooters. One advantage of MIL scopes is that the mil-dot divisions in the reticle can be used to estimate range to a target. If you know the actual size of a target, you can calculate the distance to the target relatively easily with a mil-based ranging reticle. Watch this helpful NRA video to see how this is done:
Let’s say you’ve purchased a new scope, and the spec-sheet indicates it is calibrated for quarter-MOA clicks. One MOA is 1.047″ inches at 100 yards, so you figure that’s how far your point of impact (POI) will move with four clicks. Well, unfortunately, you may be wrong. You can’t necessarily rely on what the manufacturer says. Production tolerances being what they are, you should test your scope to determine how much movement it actually delivers with each click of the turret. It may move a quarter-MOA, or maybe a quarter-inch, or maybe something else entirely. (Likewise scopes advertised as having 1/8-MOA clicks may deliver more or less than 1 actual MOA for 8 clicks.)
Reader Lindy explains how to check your clicks: “First, make sure the rifle is not loaded. Take a 40″ or longer carpenter’s ruler, and put a very visible mark (such as the center of an orange Shoot’N’C dot), at 37.7 inches. (On mine, I placed two dots side by side every 5 inches, so I could quickly count the dots.) Mount the ruler vertically (zero at top) exactly 100 yards away, carefully measured.
Tactical ace Zak Smith of Thunder Beast Arms employs a simple, handy means to store his elevation and wind dift data — a laminated data card. To make one, first generate a come-up table, using one of the free online ballistics programs such as JBM Ballistics. You can also put the information in an Excel spreadsheet or MS Word table and print it out. You want to keep it pretty small.
Above is a sample of a data card. For each distance, the card includes drop in inches, drop in MOA, drop in mils. It also shows drift for a 10-mph cross wind, expressed three ways–inches, MOA, and mils. Zak explained that “to save space… I printed data every 50 yards. For an actual data-card, I recommend printing data every 20 or 25 yards.” But Zak also advised that you’ll want to customize the card format to keep things simple: “The sample card has multiple sets of data to be more universal. But if you make your own data card, you can reduce the chance of a mistake by keeping it simple. Because I use scopes with MILS, my own card (photo below left) just has three items: range, wind, drop in MILS only.”
Once you have the card you can fold it in half and then have it laminated at a local office store or Kinko’s. You can keep this in your pocket, tape it to your stock, or tie the laminated card to your rifle. If you regularly shoot at both low and high elevations, you may want to create multiple cards (since your ballistics change with altitude). To learn more about ballistic tables and data cards, check out the excellent Practical Long-Range Rifle Shooting–Part 1 article on Zak’s website. This article offers many other insights as well–including valuable tips on caliber and rifle selection.
Scope-Cover Mounted Ballistics Table
Another option is to place your ballistics card on the back of the front flip-up scope cover. This set-up is used by Forum member Greg C. (aka “Rem40X”). With your ‘come-up’ table on the flip-up cover you can check your windage and elevation drops easily without having to move out of shooting position.
Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit. And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”
Need a high-magnification scope for long-range competition? Among quality scopes with 40+ power, we think the Sightron SIII 10-50x60mm scope may be the best value on the market right now. For a limited time, these scopes are available through Amazon.com for under $980.00. That’s less than half the price of a Leupold 7-42x56mm VX-6, and about 42% of the cost of a Nightforce 15-55X competition model. The Sightron is a good product with a lifetime manufacturer’s warranty.
Half the Cost of Leupold 7-42x56mm
Proceeds from Each Sale Help Support Shooter’s Forum
MOA-2 Reticle
Target Dot Reticle
Fine X-Hair Reticle
Mil-Dot Reticle
NOTE: There are a variety of reticle options and both 1/4-MOA and 1/8-MOA click versions are offered. Read the product description carefully when ordering to be sure you’ve selected your preferred reticle type and click value.
Nightforce’s 42x44mm fixed-power Benchrest scope mounted on James Mock’s 6mm Dasher.
Nightforce 42x44mm Comp Scope for Benchrest Shooters, by James Mock
Among long range shooters the name Nightforce has long commanded respect because of NF’s great optics and durability. However, the Benchrest disciplines that require either a 10-lb or 10.5-lb rifle had to forego the use of the Nightforce scopes because of their two+ pounds of weight. Some used the Benchrest model in the Heavy Varmint category (13.5-lb max weight) but not many in the Light Varmint, Sporter, or Hunter categories. That may change thanks to a new scope from Nightforce.
The folks at Nightforce Optics listened to benchrest shooters in the lighter classes and developed a new, light weight 42x44mm Competition Scope that weighs just 20.7 ounces. This scope comes as a fixed-power 42X and is without some of the “bells and whistles” of its larger cousins.
Key features of this scope important to Benchrest shooters are: ED glass, 42X power, 44mm objective lens, 88mm eye relief (~3.5 inches), 45 MOA elevation adjustment, 35 MOA windage, 10 MOA per revolution, 2.87-foot field of view at 100 yards, quick focus, click value of .125 inch, parallax adjustment from 10 meters (~33 ft.) to infinity, and an overall length of 15.2 inches. Also, you can set a “zero” easily. After obtaining conventional zero simply loosen one set screw per turret and set the dial at zero.
I received this scope on Monday, February 15th and mounted it on my BAT-action 6mm Dasher and zeroed it for a 600-yard match on Saturday, February 20th. My first impression of this scope was the amazing image produced by the ED glass. Although it is made with a 44mm objective lens (to save weight), one cannot say that the image is not clear. The image is outstanding from edge to edge and the image color is true. Nightforce offers two reticle options: the CTR-2 and CTR-3. Both reticles feature .016″ MOA vertical and horizontal lines, but the CTR-2 includes a .095 MOA center dot.
It took a small amount of faith to shoot the scope in a 600-yard match a few days after receiving it. Although I had shot only a few rounds with the scope mounted on my BAT Dasher, I knew that the Nightforce reputation was solid and my results would depend on the “nut” at the end of the rifle.
At the match, I fired a few shots to confirm zero and really appreciated the scope’s crisp 1/8th-MOA clicks. The adjustments were spot on at the 600-yard range and there was no problem getting my zero at the 600-yard distance. Remember, I had not shot at 600 yards with this scope, but I dialed in 11.5 MOA from my 100 yard zero and the resulting impact was correct. Each eight clicks delivered a precise one-MOA movement (about 6 inches) on the 600-yard target. The picture below is at the range as I was preparing for the first relay.
Our 600-yard match (non-registered) features 20 record rounds fired on the IBS target with steel gongs for sighters. The winter mirage can be brutal in this part of the country, but the Nightforce handled it without problems. Before the match was over, the left to right wind caused me to dial in two minutes (~12 inches) of windage and the scope was precise and I posted my 3rd best score with 191/200. The very fine .095″ dot allows for great precision in aiming.
Actual target shot by James Mock at 300 yards using Nightforce 42x44mm scope. James won the match.
My next match to use the scope was a 300-yard score match on March 5th. I had one chance to zero my rifle for this match and again I had no trouble changing the zero with the crisp, repeatable adjustments of this fine scope. The day was cool with bright sunshine and switchy tail winds. The new Nightforce handled the conditions very well, even with the horrible mirage. We shot two, 10-shot targets on the IBS 300-yard target. I shot 99-3X on the first and 99-3X on the second to win the match by one point over Mitch Young. Above is my second target, and the new scope let me see every shot through the mirage. There were many others who said that they could not see their bullet holes.
Summary of Nightforce 42x44mm Review
This 42x44mm optic is everything that I want in a scope. The 1/8th-MOA adjustments are crisp and repeatable. The center dot is small (.095 MOA). The image is sharp and clear all the way to the edges, and the ED glass provides a sensational image. The turret markings are distinct and there are 10 MOA per revolution. And you get all this in a scope that weighs 20.7 ounces with a 44mm objective lens. The low weight makes this scope viable for all benchrest classes. I believe the short range Benchrest shooters will welcome this scope and pay the sales price of $1742.00 (MSRP is $1795.00). Good shooting — James Mock
Recently the CMP adopted new rules that allow the use of magnified optics, up to 4.5X power, in Service Rifle competition. The Nightforce NXS 1-4x24mm Compact Riflescope, while not designed specifically for Service Rifle competition, complies fully with the new Service Rifle optics rules and works very well. In fact, our correspondent Johnny Fisher used this scope to take third place in the recent California State Service Rifle Championship. Here’s a run down of the scope’s features and performance. Johnny says this is a “great scope” and “results are extremely promising” so far.
Gear Review: Nightforce NXS 1-4x24mm as Considered for Service Rifles by Johnny Fisher
2016 has brought with it a long anticipated rule change that allows for the use of optics in Service Rifle competition. The rule allows scopes (fixed or variable) up to 4.5 power with an objective lens no greater than 34mm. Given the strict limits on max magnification and objective size for Service Rifle optics, there are somewhat limited options on the market at this time. Service Rifle competitors are now challenged with selecting an optic that fits the rules while offering high-end performance. Thus far, it seems the biggest concerns that Service Rifle shooters have when considering an optic are: quality, repeatability, parallax, reticle choices, and durability.
Click Image for Full-screen Version.
PARALLAX Considerations
The vast majority of Service Rifle Rule-compliant scopes currently on the market have a fixed parallax. That means there is no separate focus knob to adjust parallax to target distance. Accordingly, there has been much concern about the potential for parallax error over the three different distances in Across-The-Course competition. It is possible that the repeatably-indexed head position maintained while shooting a Service Rifle, along with a little extra emphasis on sight alignment to ensure that the shooter’s eye is directly behind the scope, can greatly mitigate the potential effects of parallax error.
The Nightforce NXS 1-4x24mm comes with the parallax factory-set at 75 yards. Combined with the right amount of eye-relief and low-enough rings to ensure an easy-to-maintain and clear/full sight picture, it seems like the fixed parallax is not really the problem some folks think it may be. Below are two, 10-round test strings shot at 300 yards (each with a magazine change). Note that I didn’t drop a point, even with the non-adjustable parallax.
The Fixed Parallax is not a “deal-breaker”. Witness 20 shots at 300 yards — all 10s or Xs.
RETICLE Options
For the NXS 1-4x24mm scope, Nightforce offers two reticle types: the International Hunting Reticle (IHR) and the FC-3G (with 5.56 NATO or .308 NATO BDC hold-over features). My scope has the IHR Reticle, which provides a very clear, unobstructed and simple sight picture. The IHR reticle for the NXS 1-4x24mm boasts an illuminated center cross-hair. Unfortunately, the red-color illumination is really only intended for low-light situations and is not bright enough to offer any aid to National Match shooters competing in broad daylight at stationary targets.
ZERO-STOP (Optional)
For Service Rifle shooters accustomed to keeping track of their sight settings as “clicks from bottom”, the optional Zero-Stop might be welcome. After loosening the turret and establishing the desired Zero-stop location, tightening the set screw blocks rotation below this point. NOTE: Once set, the Zero-Stop turret only allows for one full revolution of elevation adjustment. However, the Nightforce NXS 1-4x24mm offers 20 minutes of elevation adjustment per revolution. That should be more than enough elevation adjustment for come-ups to 600 yards (even with a 100-yard zero established near bottom).
PRICE and DURABILITY
The Nightforce NXS 1-4x24mm carries a price tag of just over $1500.00. The scope just feels solid –nothing plastic — especially when compared to some of the other consumer- or recreational-grade options on the market. All touchable tolerances feel extremely tight. There was quite an amount of attention given to every little detail, as you would expect from an optic at this price point. It is hoped that the scope’s mil-spec robustness will assure continued excellent performance — even after seasons of the kind of abuse that High Power shooters put on their equipment. More will be revealed as I use the scope at future competitions, but initial results are very good. This is a quality optic. I have high hopes that it will prove a good investment.
This article appears courtesy Target Shooter magazine from the UK.
Field Target (FT) and Hunter Field Target (HFT) airgun disciplines are popular outdoor shooting sports that simulate the challenges of hunting small game. One of the unique aspects of FT competition is target range-finding using parallax and optical focus. (HFT is limited to lower power scopes, so this type of range-fiding is not used in HFT.) Range-finding is very important because the pellets shot by FT airguns drop rapidly once they leave the muzzle (pellets can drop roughly 5″ at 50 yards). If you don’t have your scope set to the correct distance, you’ll probably miss the target high or low.
FT competitors employ high-magnification (35-55X) scopes to sight targets placed from 10 to 55 yards (7.3 to 50m in the UK). Because these scopes have very short depth-of-field at high-magnification, the target will be out of focus unless you have the scope focus/parallax control set very precisely. But competitors can use this to their advantage — once the target is precisely focused, you have effectively established its distance from the shooter. FT scopes often have large-diameter wheels on the side parallax control so the focus can be set very precisely. You can then read marks placed on the scope to adjust the amount of elevation need to put the pellet on target.
To simplify the adjustment of elevation on FT rifles, competitors will place tapes on the windage knobs with marks that correspond to distances in 3-5 yard (or smaller) increments. These marks allow you to quickly spin your elevation to the setting matching the target range established with your focus/parallax control.
Field Target Accessories
There are a variety of specialized products for FT competitors that help you set up your scope for precise ranging. First, Compufoil offers a computer program, ScopeKnob, that lets you easily create accurate elevation knob tapes for your scope. ScopeKnob even comes with a built-in Ballistics Module that will calculate the pellet trajectory for you and plot range settings for your tape. Chairgun.com also offers ChairGunPRO, specialized airgun ballistics software that lets you simultaneously compare four different pellets, or different scope heights.
In the past, the A-Team offered replacement elevation knobs optimized for use with yardage marking tapes. These were offered in two versions, one which replaced the existing turret altogether and a second which clamped OVER the factory turret. Shown at right is the larger-diameter version in place over the factory turret. Unfortunately we don’t know a current source for this product, but this may help you crate something similar on your own.
Last but not least, Pyramid Air offers large-diameter parallax control wheels. According to Pyramid: “The enlarged sidewheel is the most popular FT scope accessory of all. It lets you put white artist’s tape around the rim to mark the actual distances at which the scope focuses”. A 6″ sidewheel provides over 18″ of space on which to inscribe yardage, and that means you can have a meaningful separation between 18 yards and 20 — where there is a huge parallax and trajectory difference. Though the ranges are already engraved on the rim of the wheel, field target competitors will measure them again on an actual range and write the markings on a strip of white artist’s tape.
Tips on Field Target Scope Set-Up
The creator’s of the A-Team knobs suggest taking your time when setting up a scope for Field Target competition: “We normally take from three to four hours preparing a scope to be mounted on a gun. We mark the scope in 1-yard increments from 9 to 40 yards, then to 55 yards by 3 or 5-yard increments depending on the scope being calibrated.”
Leupold now offers easy online ordering for custom riflescope dials for your elevation turrets. A custom CDS dial lets you simply “dial the yardage” to have the correct elevation at distances near to far. For example, as shown below, if your target is at 550 yards, you simply dial 5.5 on the turret index. This is possible because the dial has been customized with the particular ballistics of your rifle and your load.
“Leupold engineers do all the hard work in the lab, making sure it’s easy and fast in the field,” said Rob Morrison, Leupold’s global marketing VP. “All the shooter has to do is provide us with ballistic information. From this simple data, a custom-calibrated dial is laser engraved for that specific load.”
Order Multiple Dials for Different Bullet Types
Leupolds’ custom CDS dials are tailored to the exact load used. With the ability to quickly change dials, it’s easy to set up several loads in a single rifle with a single riflescope. Transition from coyote loads to big game cartridges with a simple change of the dial. Or you can get different dials for different cartridges if you move your optic from one rifle to another. To order a CDS dial, call 1-800-LEUPOLD or visit Customshop.leupold.com/custom-dials and click on the appropriate dial for your riflescope.
At the request of our readers, we have launched a “Deals of the Week” feature. Every Monday morning we offer our Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.
Come on, admit it — who wouldn’t like to have a .300 Winchester Magnum in their personal arsenal. Here’s a chance to pick up a nice Rem 700 in .300 WM for under $650.00. The Model 700 Long Range features a 26″ heavy varmint barrel mated to Remington’s Long Action. This model comes with a Bell and Carlson M40-type tactical synthetic stock with dual front swivel studs for a sling and bipod. The 700 Long Range also features an aluminum bedding block for accuracy. The trigger is the externally-adjustable X-Mark Pro, factory set at 3.5 pounds.
Right now Nikon is running a “Rock your Rimfire” promotion with instant savings of up to $50.00 per scope. With this program, you get a super-low price at time of purchase — there are no rebate forms to fill out or delays. While a variety of Nikon rimfire scopes are on sale currently, we think the most attractive deal is the Nikon 4-12x40mm Prostaff scope with BDC (bullet drop compensation) reticle. Right now, this scope is just $99.95 at Grafs.com. That’s a steal.
Bullet-maker Bart Sauter used this RAVpower portable charging unit to power his LabRadar chronograph at a short-range shooting match. He reports: “I bought a RAVPower pack from Amazon. It was the most powerful cell phone charger they had and it was reduced to $31. It was able to run the LabRadar for two full days without recharging and still had juice.” This unit has impressive specs: “4.5A Output: Highest output in the market, featuring a 4.5A total output capable of simultaneously charging two tablets, making it faster and more powerful than the rest. Exclusive iSmart Technology… ensures fastest and most efficient charge.”
Need quality .22 LR rimfire ammo at an affordable price? Consider Norma. Most folks think Norma only produces centerfire ammo and cartridge brass. As a result, people haven’t been looking for Norma rimfire ammo. Their loss is your gain. Accurate, reliable Norma .22 LR ammunition is in-stock right now at leading online vendors. This is good quality ammo, made in Europe. Bullets.com has Norma Tac-22 ammo in stock at $5.25 per 50-rd box (SKU: BL7819). In addition, Bullets.com offers Norma Match-22 ammunition at $7.50 per 50-rd box (SKU: BL11887).
Everyone needs a good .22 LR rimfire handgun, and the Browning Buck Mark is a classic. This stainless, bull barrel version is marked down this week to $379.99. That’s a very good price. Buckmarks, with their excellent triggers and great ergonomics, are fun to shoot and VERY accurate. This is a pistol you can keep for a life-time and pass on to your kids. Browning says: “Every Buck Mark starts out as a solid piece of aircraft-grade 7075 aluminum alloy, and then is CNC machined to exacting tolerances. The crisp single-action trigger, hand reamed chamber, target crowned barrel and finely adjustable target sights mean the Buck Mark comes ready for fun straight from the box.”
6. Widener’s — Norma 203B and 204 Powders on Sale
Looking for an excellent powder for your .308 Win, 6BR, or other small-to-midsized cartridge? You should consider Norma 203B. This Bofors-made powder is essentially the same as Alliant Reloder 15, which has set many records in the 6mmBR and 6mm Dasher cases. Right now Norma 203B is on sale at Wideners.com for just $19.95 per pound. That’s a great deal for an outstanding propellant. Other vendors charge up to $29.00 per pound for Norma 203B. Widener’s also has 8-lb jugs of Norma 204 powder is also on sale now for $139.00 (which works out to $17.35/lb). Norma 204 has a burn rate similar to H4350.
7. Amazon — Kowa 60mm TSN-601 Spotting Scope Body
If you are looking for a rugged, reliable, and affordable spotting scope to watch flags, mirage, and shot spotting discs, this angled-body Kowa TSN-61 will do the job. These Kowa spotters have been used successfully for years by prone and High Power competitors. Sure the glass is not as sharp as the latest top-of-the-line HD spotting scopes, but the TSN-61 is a small fraction of the price of high-end models which can run $2000 or more. The money you save can buy four premium hand-lapped barrels. NOTE: This item is the scope body only. Eyepieces are sold separately — expect to pay $260.00 – $300.00 for a Kowa 20-60X Zoom eyepiece.
8. Harbor Freight — Ammo Box and LED Light Super Savings
Here are two great deals from Harbor Freight — both coupons are good through the end of March, 2016. We like these plastic ammo boxes better than metal .30-cal milsurp ammo cans because the plastic boxes are lighter, don’t rust, and they are much kinder and gentler to human shins and vehicle interiors. This $2.99 compact LED light works great to illuminate the interior of your gun safe. At this price you can buy three and keep a spare for your Emergency kit or vehicle glove compartments.
When shopping for a new riflescope or spotting scope it’s easy to get confused by all the technical terminology. Do you wish you had a better way to compare scopes — beyond just size, weight, and price? Well Swarovski Optik can help. The Swarovski Hunting Blog offers a helpful guide to technical terms used when comparing scope specifications. Here are some important definitions, expressed in layman’s language:
Let’s say you’ve purchased a new scope, and the spec-sheet indicates it is calibrated for quarter-MOA clicks. One MOA is 1.047″ inches at 100 yards, so you figure that’s how far your point of impact (POI) will move with four clicks. Well, unfortunately, you may be wrong. You can’t necessarily rely on what the manufacturer says. Production tolerances being what they are, you should test your scope to determine how much movement it actually delivers with each click of the turret. It may move a quarter-MOA, or maybe a quarter-inch, or maybe something else entirely. (Likewise scopes advertised as having 1/8-MOA clicks may deliver more or less than 1 actual MOA for 8 clicks.)
Scope-Cover Mounted Ballistics Table
In the past, the A-Team offered replacement elevation knobs optimized for use with yardage marking tapes. These were offered in two versions, one which replaced the existing turret altogether and a second which clamped OVER the factory turret. Shown at right is the larger-diameter version in place over the factory turret. Unfortunately we don’t know a current source for this product, but this may help you crate something similar on your own.
