No matter what style of telescope you use, you need to have some way of aiming it Instruments with wide fields of view require a rough alignment to get you into the general vicinity of your target, while higher powered, longer focal length scopes with narrower fields of view require more sophisticated aiming devices. Finders can be divided into three general classes:

1. Line of sight
2. Zero power/reflex
3. Small telescopes.

Line of sight finders are basically variations of mechanical gunsights.

They can be as simple as a cardboard tube or straw attached to the scope or be a little more sophisticated and have V-notches to align with a pointer to aid in aiming. These units are overall lightweight, inexpensive, but they work with wide-field instruments such as binoculars and the Astroscan from Edmund Scientific and its' clones.

Zero power/reflex sights all use LEDs. They all project an image on an optical window, have variable brightness, and can be divided into three general groups.

1. Red dot
2. Rigel Quickfinder
3. Telrad

Red dot finders are just that, they project a red dot on a window that is aligned with the object of interest. All zero power finders are best used with both eyes open. This speeds acquiring the target and decreases parallax. Their attributes are low price, light weight and simplicity. The original red dot finders were modified BB gun sights and had small fields of view. Apogee recently released a wide-field red dot finder with a 9 degree field of view. It also can be used in either red or green dot. Its' price has also been dropped to $21.95, which is a bargain even with shipping. These finders work great with the Short Tube 80mm F-5 rich field scopes sold by many vendors under numerous names. One shortcoming is the use of watch batteries whose replacement costs can add up over time.

The Rigel Quickfinder is a step up from the red dot finders, and are full featured in a small package. The Quickfinder reticle consists of two concentric circles, with the inner having a diameter of ½ degree, and the outer two degrees. The Rigel unit is lightweight, at 3.3 ounces and stands tall to allow easy use on giant binoculars and small scopes. Although its' battery will last a long time, it's a specialized watch battery like the ones in the red dot finders, and can be expensive to keep replacing if you're forgetful in turning it off at the end of a viewing session. The Rigel units contain one feature that is not available on red dots and are available at extra cost on Telrads. This is a Pulsar system, where the LED will blink on and off to allow acquisition of dim targets. The interval in which the LED stays on as well as the time it's off is adjustable. Price of this unit runs about $30 at discounters.

The third zero power finder is also the most popular, the Telrad. This is a reflex style, where a reticle is projected on an optical window which is at a 45 degree angle to the line of sight. This arrangement makes it appear as if the reticle pattern is actually being projected on the sky. The Telrad's reticle has three concentric circles, encompassing ½ degree, two degrees and four degrees. The Telrad is heavier than the Rigel, at 11 ounces. The Telrad uses AA batteries which seem to last forever, even if you are forgetful and leave the unit on for a week. Options for the Telrad include a Pulsar unit and a dewshield. Most star atlases, including digital ones have provisions for placing Telrad circles around targets to aid in acquisition. There are also some guide books, such as the Sky Spot series from Brent Watson that are specifically dedicated to using a Telrad. Harvard Pennington's "Year Round Messier Marathon" book also is A Telrad dedicated book and should be in all amateur's reference libraries.

One problem that plagues all the LED finders is dew. Dewshields are available for the Telrad, and depending on design range from marginally to very effective. The unit supplied by the manufacturer for $10-12 is worthless in my opinion. The Astrosystem's unit for about $18 works well. Adding a Dewheater strip from Kendrick Studios is probably the best way to go. A second problem with reflex finders is that they don't work well in bright skies. Since they don't gather light, you can't locate and center dim stars.

The third type of finders consist of small telescopes. The first number refers to the power, the second to the diameter of the objective or light gathering lens. Until recently the most common type of these finders were straight through viewing, with the image turned upside down and flipped left to right. Recently right angle versions appeared which can be more comfortable to view from at certain angles. These usually give an image that is correct vertically, but flipped right to left. Correct image finders with either 45 degree or 90 degree diagonals are also now commonly available. The big problem with erecting prism diagonals in the optical train is the loss of light that can be encountered with additional reflections. The positive attributes are the ease of use, and usually more comfortable viewing position. When it comes to mounting brackets, those with two rings and six point adjustments (three on each ring)have also been the preferred design. Recently some brackets with two adjustment screws and a spring loaded plunger at the site of the third screw have become available. The other ring has a rubber O-ring to fix it in place in a stable fashion. These are actually easy to adjust and hold their adjustments quite well. The higher the power, the smaller the field of view. They can be grouped into the following types:

1. 5x24
2. 6x26/6x30 - inverted and correct image
3. 8x50/9x60
4. Giant finders - 80mm and up

The 5x24 finders are included with many beginner scopes. There are two words that can be used sum up their quality and usefulness - TRASH and GARBAGE. Unfortunately these finders have major shortcomings that have probably dissuaded more newbies from further pursuing the hobby than the shaky mounts and poor quality eyepieces that are included as original equipment with beginner scopes from department stores. If you can find it, you can't observe it, and these units are deemed for failure from the start. To begin with many of the more recently manufactured units have PLASTIC objective lenses. Those that are manufactured from glass are simple lenses, not achromats. What's the big deal? They can't focus all colors of light to the same point of focus, so there is a color fringe around all bright stars. To combat this, the manufacturers place a plastic annulus of small diameter in mid barrel to correct this chromatic aberration. Unfortunately this also blocks half the diameter of the objective and you end up with not much more aperture than your naked eye with a fully dilated 7mm pupil. A simple sight tube with a cross hair would work just as well. Add to this a poor quality mounting bracket that is easily knocked out of alignment, narrow field of view and you have all the ingredients for major frustration. Bottom line, if you have a scope with one of these finders, plan on replacing it ASAP.

The next size larger are the 6x26 and 6x30 finders. These are usually of higher quality, although there are still some with non achromatic objective lenses. These will show some larger globular clusters and usually have higher quality mounting brackets. The erect image versions are usually the 6x26 versions. They will collect less light than the 6x30's, but are a little easier to use. These are light years better than the 5x24's. They cost any where from $35-50 with brackets. They are available for half that used on Astromart.

Far better and much more practical than the 30mm finders are the 50 and 60mm sizes. These will penetrate to deeper magnitudes and tend to come with sturdy mounts. Some also have the ability to add an illuminator for the crosshairs which makes precise centering of faint objects possible. The illuminated 7x50 Takahashi finder I use for centering guide stars for CCD imaging is capable of getting the star centered on the chip due to its' excellent reticle design and the illuminated crosshairs. These will cost anywhere from $45-75 with brackets, but once again can be found on Astromart for half that , especially if you're willing to accept a few scratches from adjustment screws.

Finally there are the giant finders. These are of 80mm and larger size and are great for locating faint objects and large objects with low surface brightness, such as M 33, the Helix and the Rosette nebulae. These require heavier mounting hardware such as the rings and mounting from Losmandy. In addition they may require additional counterweights on the scopes.