Finder scope

From Scope F70076

The finder scope is a simple 5x24 (5x magnification, one inch aperture, helix focuser) all-plastic scope. The limiting magnitude of such scope supposed to be 8 but in my conditions it seems to be 5. The finder scope is very useful, you should move the telescope so that the object is in the center of the crosshair, and the object would then be visible in the eyepiece. I have been able to see the crosshair even against the darkest sky, though it is difficult, you can though certainly always see the edges of the field of view. Some more expensive finder scopes have the crosshair or a dot in the center lightened, but this appears to be not so good, as seeing a lightened object may make you not been able to see the fainter stars and objects.

The field of view of most finder scopes is 5 degrees, so likely also this finder scope has that field of view. Such field of view is enough for some combination of fainter stars, but not enough for having even two stars in the same constellation in the same field of view.

I couldn't find any objects without the finder scope. There is also some additional use for the finder scope -- you can just look over the edge of the finder scope to see where your telescope is pointed, for that you should look at the finder scope so that your eye is on its axis, which means that you don't see the sides of it, and move the telescope so that the outer circle of the finder scope is around the area which you want to see. That way you can also see whole constellations. When you move the telescope that way, you would see the star which you want your telescope to point to, appearing in the finder scope, then move until that star is in the center of the crosshair. There is also a hole below the finder scope, you can move the telescope so that you can see the star through that hole, but it is somewhat difficult to look through that hole. I found that the best way to move the telescope is by holding it with the left hand from the two lower thumb knobs of the screws which fasten the spider.

The finder scope should be aligned first, it has three adjustment screws, but it isn't so precise instrument as it looks like. When you cannot fix it properly, open all the adjustment screws, remove the finder scope, then wrap the film inside the fastening ring around the finder scope, and put the finder scope back into the ring, making sure that the film isn't below the adjustment screws. At a daytime, move the telescope so that some well-determined object such as the corner of a house, is in the center of the eyepiece. Open the upper adjustment screw, with two lower adjustment screws move the object as close to the center of the crosshair as you can, and then tighten slightly all the adjustment screws. Then bend the scope to align it even more exactly, and finally tighten the adjustment screws even more. That way you can align the finder scope very exactly, and it only goes slightly out of the alignment when you strongly knock it with hand.

Some telescopes similar to this telescope, such as SpaceProbe 3 Altaz, have no finder scope. They have a viewfinder with a bright spot, which is really useless and is better to switch off, as anything bright makes seeing the sky even more difficult. If you have light polluted skies, the best solution is to buy a finder scope, plastic finder scopes are very cheap, but are almost indispensable with light polluted skies. But if for some reason you cannot buy a finder scope, then the only option is to do all the star hopping with the widest view eyepiece. This is more difficult than with a finder scope, and thus not a good option especially for beginners, who have difficulties in finding objects and so. But it is still possible, don't lose hope, you can use your telescoe even without a finder scope, though it is somewhat more difficult.

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