Hi there , ihave recently aquired a celestron firstscope 80 refractor , the objective lens although in good condition was very dirty ( the result of being kept in dusty shed with no dust covers ) having removed and cleaned objectives i have noticed that the front lens of the doublet seems to be more convex on one side compared to the other, and as a result or my stupidity and not noticing i am unsure whitch side should fit to the second element ( i.e. more convex side facing second element or facing away ) i would realy appreciate any advice u may have as i currently have a dead scope ....thank ? s alot hope u can help......
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Put the eyepiece with the largest number written on it into the telescope. DO NOT USE the 2x barlow if you have one. This will double the power of the eyepiece. Your scope is too small to use the 2x barlow.
Now go outside during the day time and practice focusing on a distant object.
This may also help you: http://www.texasastro.org/telescope.php
This is an air separated doublet (invented in the 1700s). Each lens element is made of a different type of glass to reduce false color. So if you get it back together wrong you will notice the bad image. Look at the edges of the elements the thinner one usually goes in front. The concave surface of the rear element should also face front. With the plastic separation ring in place the convex surface of the front element should not come into contact with the rear element's concave surface. It shouldn't rock, there should be about 1mm air separation between them. On shorter focal length refractors (under 500mm) the front surface of the front element has less concavity that the rear surface. On longer focal lengths they are about the same. All I can say is try this and if the image isn't that great flip the front element and try it that way. And don't feel too bad we've all learned the hard way to mark the edges of the elements as we take them out. HTH
SMA is for symetrical modified achromate. A Kellner eyepiece design. This is an inexpensive eyepiece, but not a bad one. A lunar filter is basically a sunglass lens for the eyepiece to cut down on the moon's brightness. ScopeStuff.com for camera adapters. HTH, Geo.
The rattling sound is a KNOWN ISSUE with these scopes. It actually does not affect anything. The scope is what is called an acromatic refractor. ALL ACROMATIC REFRACTORS show color fringing around bright objects. You would need to buy an APOCROMATIC refractor with 3 lenses to get true color correction. These scopes are very expensive to buy.
You can also use a "minus violet" filter to eliminate most of the color fringing in that scope. If the scope cannot be collimated it should be returned to Meade.