JeffPo's Finders Page
Last update: 09/05/19
For the most part, telescopes offer a very narrow view of the sky. Trying to point it at a specific spot can be frustrating. There's where finder scopes come in to help. They offer a wide field of view, that makes it much easier to point your telescope. Once they are aligned with the main telescope, it's a simple matter of just putting the crosshairs of the finder scope on the object or region you want to look in. With magnified finders, you can sometimes see the brighter deep sky objects. And of course a finder scope allows you to hop from one star to another as you narrow in on your target, guided by the stars of your star chart. Below you'll see the various finder scopes and pointing devices I use on my telescopes.
Finders
This is an Orion illuminated finder that I now have on my Meade LX100 telescope. It's an 8 x 50, which means it magnifies 8 times, and has a 50 mm objective. The reticle is illuminated via a battery operated red LED that attaches to the side (the silver thing). The advantage of an illuminated finder scope is that sometimes the black lines of a standard finder are hard to see against the dark sky. Glowing read lines are readily visible.
The illuminated reticle is actually designed to help with polar alignment. It has a circular hour section meant for the placement of the star Polaris, the north star. Given Polaris is offset a bit from the true celestial north, it slowly rotates around the celestial north. It does one revolution in approximately 24 hours.
By dialing in the date and time on this Polaris setting plate, it will tell me which section to place the star Polaris in for my telescope mount to be polar aligned (which is needed for deepsky photography). Actually, Polaris has moved enough in the sky such that it is now slightly below the boxes, so the finder has become outdated. But it's still close enough such that I can estimate where it should be.
This is an Astro-Physics 8 x 50 illuminated finder that came with the used Celestron Nexstar Schmidt-Cassegrain telescope. It is just like the Orion finder scope above, in that it has a glowing red polar alignment reticle to aid in polar alignment.
This is the 8 x 50 finder scope that originally came with my Meade LX100 Schmidt-Cassegrain telescope.
It has the standard black crosshairs, typical of common finder scopes. This finder is large enough to be very effective. I have switched this finder to my Meade Starfinder telescope because I upgraded the LX100 to an illuminated finder and the Starfinder had a smaller 6 x30 finder as a default.
The finder scope on my Orion Shorttube 80mm refractor is a bit unique. It has standard black crosshairs. It's a 6 x 26 power, and it gives a correct orientated image. Normally a finder scope, which is just a small refractor, will give an upside down view. Most astronomers don't really care about this. But if the telescope is used for terrestrial viewing, like as a spotting scope, one would want the image to be upright. Though true be told, I've used my refractors all my life with the upside down images and never thought twice about them.
This is the finder scope on my Vixen 80mm refractor. It has standard black crosshairs. I don't see any markings on it, but it's typical of the small finder scopes on small refractors. It gets the job done.
This is the finder scope on my Orion Skyquest 8XT dobsonian telescope. It has standard black crosshairs. It is however, unique in two ways. First of all, like the finder on the Orion ShortTube, it gives a correct orientated image. And secondly, instead of a straight thru view, it has a diagonal such that the viewing angle is a right angle (i.e. 90 degrees). Some folks find this to be more comfortable to look through, though I find it a little more difficult to use when initially pointing the telescope (this is where reflex sight finders, discussed below, come in handy).
Reflex Sight Finders
Reflex sight finders work by projecting an image on a glass window, which is then displayed against the sky. It's basically a heads up display, like you'd see in a fighter jet. They have zero magnification. You're basically seeing a red dot, or cross hairs, or circles projected upon a natural looking sky. They have two distinct advantages. The first is that they are very easy to use/point. While normal finder scopes are easier to point than the main telescope given their wide fields of view, they can still be a little cumbersome to use when trying to get them on target. With the reflex finder you see the sky as it is, so it's easier to point. And the second advantage, which also makes it easier to point, is that you use both your eyes. You just look naturally through it. You don't have to shut one eye like you'd normally do with a regular finder. The disadvantage of course is that if you're trying to star hop using faint stars, you might need the magnification of a normal finder. And of course a normal finder can also sometimes show the brighter deepsky objects you're going after. Nevertheless, reflex finders have revolutionized the hobby. Some telescopes are now shipped with them instead of a normal finders. I actually use them in conjunction with a normal finder. That's right, on some of my telescopes I have both a normal finder and a reflex finder. I use the reflex finder as the initial pointing device. Then if need be, I'll switch to the magnified finder to zero on in. They also double as a teaching tool when a visitor wants to know where your telescope is pointed. They can easily glance at a reflex sight to see where the scope is pointed in the sky.
This is a Telrad reflex sight and basically the one that started the revolution.
This neat little device projects concentric rings of red light onto the sky, like a bullseye. What you get is an un-magnified, and non-inverted view of the stars with these rings of light pointing the way. I use it on my Meade Starfinder telescope.
I'm still totally amazed when I can find a faint galaxy just by positioning the Telrad pointer where I think the object should be. "...lets see....it's half way between that star and that star....bingo!!!". It's that easy. I really recommend getting one of these devices or one of its "cousins" that are on the market.
The only "negative" is that given the viewing window is open to the sky, it's prone to dew up very quickly. There are some dew shields out there to help keep the dew at bay, but I took an active route and wired a couple of resistors (covered in shrink-wrap) under the glass (powered by 12volts) to heat it up a bit. This keeps the dew away just fine.
This is a Rigel reflex sight. It's the major competition to the Telrad.
It also projects red concentric rings onto the sky. The major difference is that it's about half the field of view of the Telrad (4 degrees versus 2 degrees), it has a smaller footprint, and it's lighter. It also has the ability to pulse the reticle off and on, though I've never used that feature. I use a Rigel Quikfinder on my Orion Skyquest 8" dobsonian telescope. I'll probably eventually add a heating resistor to it to keep away the dew, like I did with the Telrad.
This is a Daisy Electronic Point sight. It is made for use on pellet and BB guns.
It uses an LED to project a tiny point of red light onto a lens. It basically works just like the Telrad, although less complicated and it is very light. Unfortunately, it is made for daytime use. The lens has a dark coating that only the brightest stars show through. On top of this, the LED is too bright at night for my liking. The brightness problem was remedied with the installation of a variable resister into the circuit. I can now dim it to what ever level I want. I have noticed that I keep it at the same level all the time, so a simpler approach would be to just add a straight resister. As for the dark lens, this isn't a problem if you use it with both eyes open. I made a little wood mount for the sight and use rubber bands to attach it on top of my finder on my LX100 telescope. It works great. It's not as good as the Telrad, but it gets the job done. I use it to point my scope in the general area of my target. I then switch to the normal finder if needed.