Posts Tagged ‘dot sight’
by Tom Gaylord, a.k.a. B.B. Pelletier
This report covers:
• Tech Force TF90 dot sight
• How does a dot sight work?
• Easier to use than open sights
• Not the latest and greatest
Tech Force TF90 dot sight
I was right there when this Tech Force TF90 dot sight was being designed. I watched it evolve over several years of development, as each new model was revealed at successive SHOT Shows. I even tested a forerunner of this sight in the 1990s for The Airgun Letter by mounting it on a Beeman P1 pistol.
The Tech Force TF90 was developed by Compasseco, who used a Chinese optics factory that also made sights for their military. According to Duane Sorenson of Compasseco, the optics and manufacturing details of this sight were superior to similar Chinese-made dot sights because of who built it. In the 1990s Compasseco did a lot of business in China and had enough influence to get products designed to their specifications, and Duane was especially proud of this sight.
You can see from the picture that the outer shell of this sight is square, yet the optics are round. The objective lens is 28mm in diameter, which is in the middle size range for today’s dot sights. Still, when you look through the sight, everything is clear and sharp, because the optics are very clean and there is no magnification.
The base is adaptable to both 11mm dovetails as well as Weaver dovetails. Everything you need comes with the scope, including elasticized square lens covers. It can fit on a wide variety of airguns and firearms.
The base is integral with the sight tube. There’s nothing to do except clamp the sight to your airguns or firearms, and, yes, this sight should work well on firearms of at least the rimfire class. You’ll need a recoil stop if you mount this on a gun that recoils and use the 11mm mount base, because it has no stop built in. The Weaver base takes care of that, of course.
This is a very small sight. It’s only 4-1/2 inches long, and the clamping base is just 2-3/8 inches long. That makes it ideal for those vintage air rifles that weren’t really made for scopes but have 11mm dovetails for peep sights. I mounted it on my Hakim rifle and there was room to spare. Now, guns that are difficult to scope – such as the vintage Walthers, FWBs and Dianas — can have this optical sight installed.
The adjustments are the same elevation and windage knobs you’ve used with scopes. I don’t have any information about how far each click of the adjustments will move the 3 MOA dot, but I’ve been adjusting it as though it has quarter-minute clicks, and so far (at 10 meters) it seems to have adjusted correctly.
What appears in the first picture to be the adjustment knobs are really caps. Remove them, and the knobs are adjusted with a screwdriver or coin. The clicks are very precise in both directions. The scales on the knobs, however, have no corresponding reference marks on the body of the tube. So, adjusting the sight is a matter of counting the clicks for each adjustment.
The lenses appear to have a ruby coating. The tint is red, and I remember Duane telling me something like that. Ruby coatings are not really made from the mineral ruby. They’re just called that because of the color. The red may help with certain light transmission. Steiner made them famous years ago, but they aren’t commonly seen today. They can leave the other colors looking washed out, but they don’t look like that to me. I am red-green colorblind, so I’m not the best judge.
The dot is a 3 MOA dot, which means it covers approximately 3 inches of area at 100 yards. But there are 7 different rheostat settings, so the dot can be made very bright. I find this sight to be many times brighter and more visible than the cheaper sights that sell in the same price range. This is more in line with my vintage Tasco Pro Point sight, as far as visibility is concerned.
As the light is intensified, the dot expands in size. There’s no good way of measuring this, so don’t ask how much. You use only as much brightness as you need to see the dot against the target, and I believe that cancels the expansion tendency. In other words, if the dot is just bright enough to see, it will always me about 3 MOA.
How does a dot sight work?
A dot sight works like a telescopic sight. When the adjustments are changed, the internal mechanism (an LED aimed at a lens with a reflective surface on one side) moves the dot without apparent movement to the user. The dot remains centered in the window as long as your head is on the stock at the same place every time.
People will tell you that dot sights don’t have parallax, but that’s incorrect. They have the same tendency for parallax as scopes. Because they don’t magnify the target, the movement (of the dot against the target as the aiming eye moves) is hard to see — but it’s there. And the sight will do its best at one range over all others.
Easier to use than open sights
But here’s the deal. The amount of parallax error from a dot sight is less than the aiming error that results from an incorrect sight picture with traditional open sights. Said a different way, it’s easier to be accurate with a dot sight than with traditional open sights. And, as eyesight degrades, this benefit becomes more pronounced. So, people with poor eyesight will often find that dot sights help them shoot better than they’ve been able to shoot with open sights.
Not the latest and greatest
A lot of time has passed since this TF90 was new, and the technology has certainly advanced far in this field. Today, we have dot sights with different colored dots, as well as different reticles to select — all in one sight. The TF90 was advanced for its day, but in today’s market the same features are offered by a number of manufacturers. However, there’s one huge difference. Nobody is selling a sight of this quality at this price! You get a bundle of quality for the price of a bargain-basement sight. That is what you have to consider when looking at this one.
There are a limited number of these available; and when they are gone, there will be no more. If a dot sight is something you’ve thought about buying, you may want to consider getting one or more of these. I have 2 Tasco Pro Points that I’ve owned for more than 15 years. At one time they were considered very good sights. Today, they have been surpassed by technology — but that doesn’t make them worse. They’re still very good dot sights, and so is the TF90.
I’ll be reporting on this sight in future reports of other airguns — with the Hakim air rifle at 25 yards being the next one I do (click to read the Hakim 10-meter test with this sight). While there won’t be a Part 2 to this report, you’ll get to see how well this sight performs. I don’t think I’m sending this one back to Pyramyd Air, because I can always use one more good optical sight!
by Tom Gaylord, a.k.a. B.B. Pelletier
Today, you’ll get a twofer — thanks to blog reader Les, who asked about adjusting dot sights and lasers. I said I would test the Umarex MORPH 3X with a dot sight, so I thought I’d combine that test with instructions on how to adjust the sight to hit the point of impact.
I hadn’t considered testing a laser on the Morph, but I can certainly describe how to do it. I’ll get to that at the end of the report.
The dot sight
What is a dot sight? Well, once you understand what it is, you’ll understand that adjusting one is the same as adjusting a scope. Because that is what a dot sight is — a scope without the magnification (usually) or the crosshairs!
On scopes, the crosshairs or reticle are lines that you see through to see the target. By adjusting where the lines are, you can adjust where your shot strikes the target. I think most folks understand that.
All a dot sight does is substitute a glowing dot of light for the center of the crosshairs. In other words, the intersection of the crosshairs is replaced by a glowing dot of light. Put that over what you want to hit; and if the sight is adjusted properly, it works the same as a scope. No one other than the shooter can see the dot.
The glowing dot is different than the crosshairs because it isn’t a solid object. It’s a reflection on the surface of a lens that appears in your line of sight. You can see it because the reflection is physically there, but it isn’t anything that can be touched, anymore than you can touch an image in a mirror. But you can adjust where the dot is seen by adjusting the lens that reflects it.
If you have a dot sight, try looking through it and moving your head around from side to side and up and down. You’ll note that the dot moves against the target quite a bit. That’s because you’re moving your eye, and that changes where the reflection of the dot appears to be. You can do the same thing with the reticle of a scope, but not to the same extent. Where a scope reticle will appear to move just a little against a target, a dot appears to move more. That’s the difference between looking at something that is physically there and something that’s just reflected off a curved piece of glass.
That should warn you that dot sights have a lot of parallax problems and require consistent eye placement for every shot. The same is true with open sights, but open sights give cues when the alignment isn’t right. The front sight moves relative to the rear sight. But a dot sight is just a single point of reference, so you can’t see the misalignment as easily. Therefore, the placement of your head is extremely important if you expect to hit the target every time.
What I’m saying about dot sights applies to the older tube-type sights, like the one I’m using in this test. I suspect, like all technologies, dot sights have become more precise in recent years. But my experience is with the older style.
Don’t get the idea that dot sights are impossible, though, because they’re not. Though they are somewhat dicey to use. It’s not as bad as ice skating on stilts.
Dot sight adjustment
Now that you understand what a dot sight is, you should know that it adjusts in the same way as a conventional scope. One knob controls the up and down movement, and the other controls the left and right. Sighting-in a dot sight is no different than sighting-in a scope. You select a point of aim, which you hope will also be the point of impact and hold on it as you shoot. If the pellets strike the target low and to the left, the sight has to be adjusted up and to the right.
Like a scope, it helps to begin sight-in of a dot sight at a close target. I like starting at 10 feet away, and I adjust the sight until the pellet is striking the target on the centerline and as far below the point of aim as the center of the sight is above the center of the bore. Then, I know I can back up to 10 meters, and I’ll be on paper. I may need to refine my sight adjustment a little when I shoot at 10 meters, but this is the fastest way I know to sight in an airgun — especially one that cannot be boresighted.
But what if you’re at a public range and can’t shoot at 10 feet? That’s when I put up a 2-foot by 4-foot light-colored paper backer and staple my target in the center of that. Even at 50 yards, there’s a good chance my shots will land somewhere on that big piece of paper if I shoot at the center of the target. When even that fails, I enlist the help of a spotter to watch the berm. I shoot at a dirt clod we can both identify and he watches through the binoculars that I always carry to see where my bullet strikes relative to the dirt clod.
Tasco Pro Point
I mounted a Tasco Pro Point dot sight to the rail on top of the Morph and was ready to commence sight-in. The Pro Point is a dated design, but it was good quality 15 years ago and still works well today. The amount of parallax is small for a dot sight, but I still watch my head placement every time.
It was very easy to install the Pro Point on the Morph. The Weaver bases on the Pro Point clamp right to the Morph’s rail, and clamping pressure plus the keyed cross-slots hold the sight in place.
Tasco Pro Pont dot sight fits the Morph quite well.
I think it was Victor who asked me how I stop the BBs from bouncing back, so today I thought I’d show you. I photographed my target setup, so you can see the light and the Winchester Airgun Target Cube with the Shoot-N-C target pasted on its front.
Absolutely no BBs bounce back using this setup. The target cube is starting to slough off small pieces of styrofoam, now that over a thousand shots have hit it, but nothing gets through it and nothing bounces back.
On to the shooting
At first, I shot the Morph in carbine form offhand at 15 feet (I’m using Umarex Precision steel BBs). I dialed the red dot intensity up to No. 8; because when the Shoot-N-C target turns green, it’s so bright that it masks the dot. Even at the 8 setting, I could barely see the dot against the target, once it changed from black to green (or yellow — I can’t tell…I’m colorblind.). Of course, when you shoot offhand, the dot seems to move all over the target — even at 15 feet.
Seeing the accuracy of the carbine made me want to shoot the gun rested. I brought in a kitchen chair, turned it around and used the back as a rest for my next group.
Seeing this result made me want to see just how good the gun could shoot. So I adjusted the dot to the right and shot another 10 rounds.
Let’s back up
Seeing how good the Morph could do at 15 feet prompted me to back up to 25 feet and try again. This was also a rested group of 10 shots. I adjusted the sight a little more to the right for this one.
I was running out of the smaller bulls, but with a dot sight that poses no problem. Since the BB goes where the dot is, the size of the target has no influence over where you hit, as it would with a peep sight or a post and notch using a 6 o’clock hold.
At 25 feet the group opened up a bit, but it’s still respectable. There’s a single BB above the bull in the cardboard. This is a larger bull; but with a dot sight, that doesn’t pose a problem. The sight is still not far enough to the right, and notice that the impact point has climbed just a little. The orange dot in the center of the bull was the aim point.
I don’t have a laser that will fit on the Picatinny rail of the Morph, so I can’t mount one, but let’s talk about how a laser differs from a dot sight and a scope. A laser actually shines a light on the target. What you see is reflected from the target — not from a lens inside an optical device. The laser dot can be seen by everyone — not just by the shooter — the way a dot sight can. And because the laser dot actually hits the target, there can never be any parallax. What you see is actually there, on the target.
With a laser, there’s nothing to look through. Think of a laser as a very powerful flashlight. It isn’t actually a sight. It’s more of a designator.
A laser is adjusted just like a scope or dot sight, except you’re adjusting where the light actually falls. So, the procedure is to use a separate sight to sight-in the gun, then adjust the laser so it’s on the target when the other sight is.
Adjusting a laser is usually different than adjusting a scope or a dot sight. There aren’t click adjustments, as a rule, but there are screws that push the laser tube in the direction you want it to go. This may be backwards of how a scope’s adjustments move, so read the laser’s manual before you start adjusting.
Distance is limited
Lasers can’t be seen very far on bright days, so they’re limited in distance. You can look at them through a scope which increases the distance at which the dot can be seen, but even then the laser is a limited-range sighting aid. A 50-yard shot is very far for a laser. Most shooters set them up for very close shots, like 20-30 feet. They use their other sights for longer distances.
Les — I hope this helps you with the sight-in procedure for dot sights and lasers. Let me know if you have more questions.
The Morph 3X rifle and pistol is a unique airgun that’s accurate and powerful at the same time. The double-action trigger-pull may take getting used to, but it poses no problem as far as accuracy goes.
I find the Morph accurate, conservative of gas and trouble-free to operate. If you want an accurate BB gun that also has power, check this one out.