Celestron Rich-Field 80


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Subject: Re: vote by xxx.xxx.211.143
By: Anonymous (xxx.xxx.189.129)
Date: 09/28/2002 01:19:36 pm PDT
>I found this telescope a pleasure to use and a pleasure to look at. It does, however, have defects which may or may not interfere with an owner's satifaction with the possession/use of this instrument; that being dependent on the use the scope is being put to and the expertise of the user.
>
>Good: The focuser functions well. It is light and easily transportable. It sets up and takes down quickly. Many would prefer to just leave it set up all the time. The tube has a high quality glean, it is metal, the objective is clearly multicoated on all surfaces: the color is a deep green and there are no white reflections indicative of uncoated surfaces. The focuser works well and smoothly. It provides very good terrestrial views through all magnifications up to 50X per inch of aperture (not tested above that figure). It provides good astronomical magnifications up to 80X, fair into the hundreds-X, adequate/borderline quality at 50X. In focus, stars appear as pinpoints across the entire field of view. Though one can detect the cassini division, one cannot actually see it. The double double in Lyra is clearly seen/resolved into 4 airy disks with diffraction rings at 80X and above.
>
>Negatives: The star test is ugly; a fuzzy reddish circular ball with a double line near the fuzzy perimeter on one side, an unfuzzy oblate shape on the other side of focus with a bluish ring of blue serving as the boundary of the perimeter. At the very highest powers, the just outside of focus image has the appearance of an airy disk with a series of touching airy-like disks descending away to one side; each disk being about half the brightness of the former. On the moon, a very pleasant view is gained. It is obvious that there is only one focuser position of best focus. In this sense it snaps into focus. However, I found I was always squinting my eyes, because the view, just was an indefinable bit off of being crisp. Venus is well defined but does have a reddish side and a greenish side. The moon had a visible, but hardly distracting purple fringe. The finder seems cheap and shoddy. It works well when I have my glasses on (for normal vision) but if one needs to focus for near-sightedness, once the stars become dots, the cross hairs are almost invisible (out of focus). The manner of focusing has a cheap feeling to it (rotating/unscrewing a plastic eyepiece holder).
>
>More favorable: there are stargazers who have largely corrected the optical defects by dismantling the objective, rotating the two lens elements to different relative positions and by changing the separation of the two elements. One observer has told me that this caused the view of the cassini division on Saturn to go from being barely detectable to a vague but very noticeable light pencil line.


I attempted last night to take the objective apart to see if I could improve the resolution. I discovered that the objective elements seemed to be tightly bonded together; perhaps glued. I did not attempt to separate them.


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Subject: Re: vote by mtburr
By: Anonymous (xxx.xxx.7.54)
Date: 01/15/2003 03:51:48 pm PDT
>Lots of false color on my copy. Jupiter looks like it's boiling in purple ink. But this is not a planetary scope. It gives nice wide-field views for looking at clusters, and I imagine it would perform admirably as a spotting scope -- which, after all, is what Celestron says it is!

Dear mtburr:

Pop a 9mm Nagler on this scope (make sure to tighten the drawtube screw) and look at M42 in at a darksky site and you'll see its forte. It is definitely not for the planets, and shows color on bright stars, but then again, you get what you pay for. I have had mine for almost 7 years and take it on trips for nature and stars. It was great for Hale-Bopp with a 20mm wide field (i.e. 20x) and views of the Pleides are outstanding.
ch


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