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Subject: [M]: "Classic" 2080 upgrade
From: Geoff Gaherty
Reply To: mapug@shore.net
Date: Wed Nov 12 08:39:43 1997
I was one of Meade's early guinea pigs: I bought an 8" 2080 in December 1981, which must have been one of their earliest SCTs. Recently I've been getting back into astronomy, and wanted to make some upgrades to my telescope. Some interesting things have emerged:
1. I decided to add a 2" diagonal. I purchased a generic diagonal from my local dealer, and discovered that it didn't fit the threads on the back of my 'scope: it would take about one turn on, and then would jam, so that the diagonal hung loosely on the mirror cell. I discovered that the threaded ring from my 1981 vintage T-mount adapter would fit on the diagonal in place of the ring supplied, so was able to make do temporarily, and was very pleased with the view with my new 56mm Super Plössl.
However, I was not prepared to give up my T-mount permanently. I thought that perhaps the threads on the generic diagonal were sub-standard, so took it back to my dealer and traded it for a genuine Meade diagonal. Alas, the ring on the Meade diagonal wouldn't thread on any better than the first one, plus the barrel size of the Meade diagonal was slightly larger than on the generic, so my old T-mount ring wouldn't fit. At this point I vaguely recalled that there had been incompatabilities in the threads back in the early days, and called Meade's tech support line. Mike there was unfamiliar with early Meades; his suggestion was to find a local machine shop and have them fabricate a new ring for me.
Another idea came to my mind: swap the Meade diagonal for the generic diagonal at my dealer, so that I could use it with my T-adapter ring. Unfortunately he was out-of-stock on the generic, but had a diagonal another customer had just traded in. I noticed that this diagonal's ring, like the ones on my T adapter and my 1 1/4" eyepiece holder, had a painted black finish, rather than the anodized finish on the modern Meade ring. I had my OTA in my car, so I rushed out and tried it on my scope: a perfect fit! This diagonal must have been purchased originally about the same time as my 'scope. My dealer hadn't tried it on a modern SCT, but I'll bet it wouldn't fit. So, I left, happy with a diagonal which fitted my 'scope, and my dealer happy to be rid of a diagonal which probably wouldn't fit anything else in the store!
2. Over the years I've noticed that the corrector plate on my 'scope appeared to be getting cloudy. Last weekend, armed with the many helpful instructions here on MAPUG, I removed my corrector plate. I discovered that the cloudiness was what a deposit on the INSIDE of the corrector plate. After I removed this deposit carefully, the plate is now perfectly transparent again. There does not seem to be any similar deposit on the primary or secondary mirrors, which appear perfectly clean and clear. Although the telescope spent its first few years in the polluted air of downtown Toronto, it has spent the last 11 years out in the country, inside a winterized cottage. Anyway, if it were some sort of atmospheric deposit, why would it only affect the corrector plate?
This was one of the first Meade SCTs with coated optics (simple magnesium fluoride). I'm beginning to wonder if somehow this was improperly done and somehow the coating broke down chemically over the years and became cloudy. Any theories?
3. My next project is to install flocked paper inside the tube, following the insrtructions posted here. I've never been happy with the image contrast of this telescope, and the film on the corrector plate certainly didn't help things! What really tore it was comparing the image contrast of this scope with my newly purchased ETX. There's no way a 3.5" should show better lunar and planetary images than an 8", but that is in fact the case.
4. My major fear is that the optics of this scope may just be sub-standard, which wouldn't surprise me from some of the comments I've read here and in s.a.a on the quality of Meade's early optics. If so, at least I will have given it my best shot, and learned quite a bit about SCTs in the process.
Geoff Gaherty
Toronto, Ontario
Geoff.Gaherty@logicbbs.org