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Equipment Discussions >> Reflectors

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Reged: 09/27/13

Loc: Pinelands-near Cape Town,South...
Re: Zhumell TYCHO 254 new [Re: pftarch]
      #6118430 - 10/05/13 02:48 AM



It may be advertised at 600X, but I don't believe any claims over 2X the aperture in mm, (508X max), and, at least where I live, getting a clear view at 500X with my 10" is a tall order. My atmosphere conditions seem to dislike anything over 250X with an occasional, rare, fleeting, pristine view over 300X. (But those nights are like a once every three year occurrence for me.)

I call it a great night if I can go over 250X at all......

Peter T.

Morning Peter - thanks for your posting. Yes I am aware that any telescope that advertises magnification capability is meaningless and meant to impress the ignorant so I did not take that at all seriously other than perhaps get the hope it was a reasonable quality telescope. I must say its very well made - far better than some of the other scopes I have - my wife says I must open a "telescope sales" shop - but I was disappointed when I couldnt even get an acceptable image at around 50x. I am only interested in using the scope with newtonian prime focus photography - ie as wide field as possible so no eyepieces or camera lens. Now that I know its a B-J scope, and have a working collimator I am hoping that I can get good enough quality for my purpose - anyway I was doing the collimtion wrong initially as I thought it was a conventional newtonian and a B-J apparently is a completely different process. As regards seeing - I seldom have seeing better than about 8 arc seconds and usually around 12-15 arc seconds so fine resolution photography is ruled out. I am very familiar with seeing - I was involved with the site testing for the South African Large tlescope (SALT) - the largest reflector in the southern hemisphere - and on a good night we used to get sub arc second seeing. Anything over about 1.8 arc seconds or so is regarded as "bad seeing" - wish I had this in my location here in the city of Cape Town with its pollution, different air currents above my head etc. Incidentally even with the large telescopes I used we seldom went higher than around 200-300x and these were with telescope apertures as large as 40 inches. Incidentally in the early days of the site testing program we used a small QUESTAR - not a bad scope but then one of the observers dropped it and that was the end of that scope. Then we used an 11 inch Celestron for several years - in fact I think they still use it to measure the actual seeing every night the observatory is in operation. Anyway Im waffling - happens when you get old! Have an good weekend, Cheers Greg.

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