Best Telescope Finder Scopes
by Zane Landers
Almost any telescope, with the exception of astrophotography rigs that have plate-solving, needs a finder. The field of view of most telescopes is simply too narrow to make sighting along the tube a viable option. A good finder means the difference between quickly and easily locating your target or spending hours to get your telescope pointed at anything at all. Most telescopes include some kind of finder, but whether it’s enough for you depends on your intended use of the telescope, budget, and personal preferences.
Telescopic Finder – Zero Power Finder
Types of Finders
There are essentially two types of finders, each of which have two of their own subcategories: reflex sights or zero-power finders, and telescopic finders. Telescopic finders, or magnifying finders, are a small refracting telescope with an eyepiece with crosshairs, usually no more than a couple of inches in aperture and usually operating at a fixed magnification. Reflex sights are simply glass or plastic windows with reticles projected onto them with some kind of lens.
There are essentially two types of finders.
Zero-Power Finders
Lightweight
Low Cost
Simple
Zero-power finders can be divided into two categories: red dot finders and true reflex sights with reticles. Red dot finders, as the name implies, project a simple red dot, crosshair pattern, or similar and generally have a low cost. They look and work like a red dot sight used on firearms. Most red dot sights, in fact, are quite literally identical to the sights sold for firearms use, and tend to fit standard Picatinny rails; adapters are included or built-in to attach either directly to a telescope or a standard finder shoe. Reticle-based finders predate red dot finders, and originate with the Telrad in the 1970s. Reticle sights usually are bigger, specifically intended for astronomy, and have a large viewing window with circular reticles and/or crosshairs; the circular reticles tend to be specific sizes to help with navigating the sky via rough measurement.
Unless you are aligning a GoTo mount or trying to point at stuff that’s easily seen with the naked eye like the Moon or planets, a red dot sight is not very useful.
The advantages of red dots are their lightweight design, extremely low cost, and simplicity. However, red dot sights often have slightly tinted windows and tend to be hard to look through, are inaccurate, and often run on small coin-cell batteries which can be annoying or costly to replace. These are all concessions of the fact that they are cheap and usually weren’t intended to be put on telescopes when they were designed. Unless you are aligning a GoTo mount or trying to point at stuff that’s easily seen with the naked eye like the Moon or planets, a red dot sight is not very useful.
True reflex sights/reticle sights are usually easy to use, run on standard batteries, and can be all you need to aim even a very large telescope if you know how to use one. However, in light-polluted areas they can be hard to use as there are not many stars visible to the naked eye to use as a reference. The light from them can also interfere with dark adaptation if you are very picky. Most reflex sights also use proprietary base plates which can be either screwed or taped to your telescope tube, or attached to an adapter to fit a finder shoe.
Magnifying Finders
Shows Fainter Stars
Doesn’t Need Electricity
Heavy
Expensive
Magnifying finders are pretty much all refracting telescopes, but may or may not have an included star diagonal. Most magnifying finders without star diagonals present an upside-down image, while those with a diagonal usually have an Amici prism to present a correct up-down, left-right image and are termed right-angle correct image or RACI finders. The latter’s design means it’s easy to use one with star charts, whereas a straight-through upside-down finder matches the orientation of most reflectors but requires flipping your charts upside down. Magnifying finders may or may not have illuminated reticles, interchangeable eyepieces, or advanced focusing systems. Most cheaper magnifying finders focus by unscrewing the objective lens, while nice ones focus with a moving eyepiece like the diopter adjustment in binoculars. They are typically specified by magnification and aperture, much like binoculars. You can think of a typical 9×50 finder as one-half of a 50mm binocular; consequently using it will give slightly dimmer images than both eyes will with a pair of binoculars under the same conditions but with a similar field of view.
You can think of a typical 9×50 finder as one-half of a 50mm binocular
The main advantage of magnifying finders is that they show fainter stars than what can be seen with the naked eye and even some deep-sky objects. A 30mm aperture finder can reach about 1-2 magnitudes deeper than your eyes alone; a 50mm is about 3-4 magnitudes deeper, and an 80mm might be 4-5 magnitudes deeper. In a light-polluted locale where the naked eye limiting magnitude might only be 4 or 5 if not worse, a magnifying finder will show you roughly as many stars as the naked eye will at a dark sky site, where the naked-eye limiting magnitude is usually between 6.5 and 8.2 depending on the observer. Under dark skies, you ironically might have trouble with too many stars visible in the finder to figure out where you are aimed, as a 9×50 finder can reach down to magnitude 11 or so.
Magnifying finders also don’t need electrical power to be used, so dead batteries are at worst a nuisance if you have an illuminated reticle. They come with their own brackets to attach to a standard finder shoe, or can include one themselves too.
Standard straight-through finders are intuitive to coarsely aim without the assistance of a zero-power sight but can be uncomfortable to use when pointing a telescope high in the sky. RACI finders, on the other hand, are comfortable to use but can be extremely confusing to aim, as you have to roughly sight along the tube and then try to figure out where the RACI is aimed, which gets more confusing corresponding with the more stars the RACI can show you with its aperture and given viewing conditions.
Besides confusion as to where you’re pointed, the disadvantages of the magnifying finder design are its proneness to dew, fragility, cost, and weight. A cheap 9×50 is well over $50 USD in most cases.
The ideal combination for most telescopes is arguably a reflex/reticle sight and a RACI finder. However, in addition to the cost, a good reticle sight and RACI finder are enough to cause balance issues with many telescopes, as the center of gravity will be shifted very far back with a refractor and very far forward with a Newtonian reflector; a Dobsonian telescope may quite literally begin to tip over with a RACI and reticle sight affixed to the front, let alone a heavy eyepiece and coma corrector added to the mix. Additionally, many observers find that only one type of finder is needed, usually the reflex sight.
The ideal combination for most telescopes is arguably a reflex/reticle sight and a RACI finder.
Top Picks for Finders
The ideal combination for most telescopes is arguably a reflex/reticle sight and a RACI finder. However, in addition to the cost, a good reticle sight and RACI finder are enough to cause balance issues with many telescopes, as the center of gravity will be shifted very far back with a refractor and very far forward with a Newtonian reflector; a Dobsonian telescope may quite literally begin to tip over with a RACI and reticle sight affixed to the front, let alone a heavy eyepiece and coma corrector added to the mix. Additionally, many observers find that only one type of finder is needed, usually the reflex sight.
Red Dot Sights
SVBONY red dot sight: Version 1 fits to telescopes directly while Version 2 fits to a standard finder shoe. This is the same red dot supplied by Celestron, Orion, and a bunch of other manufacturers as the “EZ Finder II”, “StarPointer”, etc. Very basic but does the job.
Astromania Deluxe red dot sight. Has adjustable color/crosshair pattern and a slightly bigger window.
Reflex Sights
Telrad - The oldest and chunkiest reflex sight, essentially a giant empty plastic box running off AA batteries. The Telrad has 0.5, 2-, and 4-degree circles and is offered with upgrades to blink the reticle, raise the Telrad above the telescope tube, and dew shields/heaters also exist. It’s also fairly easy to wire it to run off DC power from your dew heaters or other electronics. The Telrad also holds alignment well and doesn’t suffer from parallax error, where the reticle shifts when your head moves, which can make accurate aiming difficult. However, it’s heavy, won’t fit on a small telescope, and is very prone to dewing up.
Rigel Quikfinder - The Quikfinder is a Telrad without the bulk or 4-degree circle, with the addition of parallax error, a blink/pulsing option by default, and a built-in dew shield. It weighs next to nothing and fits even a tiny telescope (albeit looking ridiculous) but the parallax error is annoying, the window is a little small, and the lack of a big outer circle makes it a little more difficult to use. Still a huge upgrade over a red dot sight, and pretty useful for casual observers or to accompany a RACI.
QuInsight - The QuInsight is a 3D-printed product from a small shop, but don’t let that stop you. It uses a glass lens for projecting its reticle, the window is extremely large and has its own dew shield, and the QuInsight reticle has 0.5, 2, 4, 8, and 16-degree circles with crosshairs and the reticle can even be rotated. The weight isn’t bad either.
Baader SkySurfer V - The SkySurfer V is entirely enclosed, won’t dew up on you, doesn’t suffer from parallax error, doesn’t have any plastic parts. However, the reticle isn’t the best, it’s heavy, and there really aren’t any tangible advantages over the Telrad.
Straight-Through Optical Finders
SVBONY 6x30 - The SVBONY 6x30 works, but the aperture is on the small side and it’s not the most comfortable to use.
Orion 8x40 - A good intermediate size between 6x30 and 9x50.
Orion 9x50 - The Orion 9x50 is again basic, but functional.
RACI Optical Finders
SVBONY 6x30 RACI - The SVBONY 6x30 RACI weighs very little and is comfortable to use, but the prism sucks up more of the meager light gathering ability of 30mm of aperture, and thus it’s not the most useful.
Apertura 9x50 RACI - The Apertura 9x50 RACI is well-made and has a lot more capability than a 6x30 or 8x40 finder.
Apertura 10x50 Illuminated RACI - With an interchangeable, separately focusing eyepiece, a classic screw-based bracket, and well-made optics, the Apertura 10x50 feels like a telescope in its own right and is much more comfortable to use than cheaper RACIs. However, you pay not only in cost but in weight and size too.
Stellarvue 13x80 Illuminated RACI - The Stellarvue 13x80 is a specialty product that needs another smaller finder or reflex sight to go with it and a big telescope to match - it’s as big as some beginner scopes, after all. As with the Apertura 10x50 however, it’s well-made and comfortable to use, and the 80mm aperture is capable of showing a lot at once.