Stargazing

I was up late last night, so I tried out a twenty dollar telescope from a everything-in-one pharmacy that was sitting around. Made in China. (of course... Thanks China!) Anyway, I've used it a few times to look about the neighborhood, and it performs fairly well--as one might expect from a cheap telescope. When directed skyward, however, it is a very tricky matter.

Relocated outside of town, in a rural neighborhood, the stars are much brighter. However, the performance was chaotic. The 4' tripod offered very little stability, and the swivel mount was very resistant, acting like a spring when applying small adjustments. In short, I look forward to buying a quality scope for stargazing.

Anyway, as far as telescopes go, I remember a little from physics classes. Aperture and focal length come to mind. If you are familiar with the dynamics of cameras, then telescopes are nothing new.


Aperture determines the brightness of the object by allowing more light in. So a larger aperture is a brighter night sky by allowing more light to enter the telescope.
Focal length is the distance between the primary lens or mirror and the eyepiece. The greater the focal length, the narrower the field of view just as your field of vision narrows as you look at something farther away.
Focal Ratio is focal length divided by aperture. I think my telescope has 43mm aperture with a 600mm focal length: f/14. This differs from photography's "f-stop". A smaller f/# will yield a larger field of view, whereas in photography a small f-stop reduces the depth of field.