Mike Morton gets immersed in the world of lightweight, short eye relief sights as he tests the new 10×40 prismatic model from Immersive Optics.
Are you the sort of shooter who appreciates the benefits technology has to offer, but likes to keep things simple when it comes to a sight? If so, the fixed-magnification 10×40 prismatic scope from Immersive Optics is one for you.
This optic is side-parallax-adjustable down to six metres. It has a choice of two different reticles, Mildot, which is the one on test here, or the more complex Mildot Extended, which provides more aim points. It measures just 135mm long and weighs 485g, including the supplied single ring mount.
While an ordinary telescopic sight relies on lenses to transfer light to the shooter’s eye, the 10×40 uses a prism to refract it. This helps keep the weight down and the length short. Best of all, it offers a field of view wider than a standard scope.
The obvious application for this is in the hunting field, where the shooter will spot his quarry and will then want to acquire it through his scope as fast as possible.
However, some target shooters will benefit from being able to lock on to their target quickly, particularly when shooting timed disciplines.
Immersive Optics 10×40 MD – key specifications
Manufacturer: Immersive Optics (immersive-scopes.co.uk)
Supplied by: Thomas Jacks (thomasjacks.co.uk)
Model: 10×40 MD
Objective lens: 40mm
Eye relief: 17mm
Field of view: 11.4m @ 100m
Minimum focus distance: 6m
Click value: 0.1 mil
Clicks per revolution: 50
Travel per rotation: 5 mil
Max elevation adjustment: 28 mil
Max windage adjustment: 28 mil
Sight dimensions: 80mm x 60mm x 135mm
Weight with mounts: 485g
Reticle: Mildot or Mildot Extended
Illuminated reticle: Six levels of brightness
Prismatic scopes are unconventional sights, and while the Immersive Optics 10×40 is shorter than usual, it’s also wider than usual, requiring the use of a correspondingly unconventional mounting system.
Luckily this scope comes with a dedicated ring clamp, which the optic has already been fitted into.
I’m usually leery of factory-mounted scopes and was concerned that the reticle would not be level once the scope had been fitted to my rifle.
But while I was expecting to have to loosen the ring mount and adjust the position of the scope, I was pleased to see it had been set up perfectly.
While levelling the reticle is important, it’s absolutely vital to ensure perfect eye relief with this scope. Immersive Optics has supplied us with three Picatinny bases of varying lengths to ensure that the 10×40 can be set up just right for you and your chosen airgun, whether that’s a full-length sporter or a shorter bullpup.
The scope comes with the medium length base already fitted, but I swapped this for the longest base, which has four Picatinny mounting points, in order to get the correct eye relief with my Weihrauch HW100 BP.
I was startled to find out that in order to achieve proper eye relief, I had to mount the optic so far back that only two of the four Picatinny mounting points were actually engaging with the rail on the rifle.
However, it turned out that this was nothing to worry about, and the manual even has a picture of a rifle configured exactly this way.
It may look a bit odd with the base mount overhanging the rail of the gun, but in all my subsequent testing I had no problems whatsoever with the scope losing zero, so the mounting base is certainly beefy enough to properly support the optic.
One problem that some rifle and scope combinations can exhibit is running out of elevation adjustment when you’re trying to zero.
The usual practice is to either replace the mounts with a fully adjustable set or to shim the rear ring. Neither of those options is relevant here, however, as the supplied scope mount can be adjusted by up to 80 minutes of angle either side of neutral.
All you need to do is loosen the screws on the mounting plate and angle the entire scope up or down.
Not only will this let you attain the correct zero in terms of elevation, but it also means you can keep the scope optically centred while doing so.
In order to do this you’ll have to remove the scope from the rifle, but because it uses the Picatinny system, the newly MOA-adjusted scope can be relocated in exactly the same place on the rail that it was in before.
Using The 10×40
The first order of business is to adjust the fast focus ring to sharpen the reticle to suit your eye.
This control was a little stiff, but will at least keep the ring in place, protecting it against accidental shift.
In contrast, the side parallax control was very smooth in operation, while the hunter-style elevation and windage turrets offered positive, uniform clicks once the turret caps had been removed.
Immersive Optics’ 10×40 comes with a scope enhancer, which many shooters will love. These devices block peripheral light from interfering with the sight picture.
Some shooters don’t get on with them, but that’s OK because the 10×40 can be shot perfectly well without the enhancer, and the scope comes with a dedicated rubber mount to hold the rear lens cover in place if the enhancer isn’t used.
When you’re shooting, the front and rear lens covers can be removed or left dangling from the optic.
However, there is a third way as the lens covers have been designed with a turret cap-shaped indentation so they can be pressed over the elevation and windage turrets respectively, effectively locking them in place.
While this is a clever solution and does work in practice, I would have preferred to have had flip-up covers, but that’s only a minor gripe.
All five scopes in Immersive Optics’ range are fixed magnification, the 10×40 being 10x, which is a pretty useful level for general airgun use.
The advantages of fixed magnification are lighter weight, fewer lenses and therefore better light transmission, and of course there’s no need to learn more than one set of holdover points for a fixed-mag scope such as this.
The main feature of this scope is its wide field of view, and to test how wide I grabbed a standard telescopic sight, turned it to 10x to match the magnification of the Immersive Optics scope, then compared the two side by side when looking downrange on a dull and miserable winter’s day.
Field of view of the 10×40 was more than double the regular scope, and the image was brighter too. Furthermore, the sight picture was sharp from one edge to the other.
I found the only real downside was the fact that eye relief and head position are critical with this optic. If I deliberately moved my head and shooting eye away from the optimal position, the conventional scope was more forgiving. However, this does mean that the 10×40 will let you know in no uncertain terms when you’ve got incorrect eye relief – and it’s then down to you to fix it.
I like the Mildot reticle. In my opinion it has just enough aim points to be useful, while still maintaining a nice clean image.
For those shooters wanting more aim points, especially in terms of windage, then this scope can be bought with the Mildot Extended reticle instead.
Crosshair thickness is a personal thing, and I initially thought the hairs were a little thick. However, having shot my HW100 BP with this scope on numerous occasions I think Immersive Optics got it right. The crosshairs will cover both a .177 and .22 pellet hole at 30 yards, making it perfectly acceptable for target use.
However, this optic is really intended for hunting, and the crosshair is thick enough to be placed over the killzone of a small quarry animal where it can be quickly and easily seen.
This scope has an illuminated reticle in red, with six levels of brightness. The control is located on the side parallax turret, and one press of the button will turn on the IR function.
Subsequent presses will toggle through the various levels of illumination, and an extended press will turn off the feature altogether.
Immersive Optics’ 10×40 is an accomplished scope that achieves its aim of delivering a wider than normal field of view in a lighter and shorter than normal overall package.
And it does all this with really great glass. I suspect some people will reject a scope like this purely because it’s unconventional. Perhaps it’s time to defy convention.