Sky and Telescope
|8 inch Reflector with 1400mm focal length at f/7
|Reflecting telescope on a German equatorial mount.
This version came without accessories as it was being rebuilt.
Hello everyone! This will be a look at a classic, vintage, 'scope.
This particular 8 inch F/7 Cave Astrola sat in a backyard junk, bric-a-brac collection for years. Every now and then, when I would drive by it on my
way to the town of Imlay City, I would notice it, and think "What a shame, but it can't have a mirror in it." Well it turns
out it does have a mirror in it, and what a mirror it is!
One day, when I came to work, some of the guys came up to me all excited, saying they had something to show me. I came around the corner, and there
it was, one sad, rusted, ancient Cave Astrola. It seems one of the guys had repaired a VCR for the guy with the junkyard
and being as he had no money, my co-worker accepted this 'scope. He was all excited, and wondering what it was worth. I told him we would look it over
at the club meeting the next evening, and let him know.
As it turns out, the 'scope as presented to him was almost worthless. Someone had repeatedly "cleaned" the mirror with paper towels and windex
until it really was more of a window, than a mirror. The pedestal eq. mount was hopelessly rusted in place, and the latitude
adjustment was set at about 10 degrees. (great if your near the equator, not so good at 43 degrees
north latitude.) The low profile focuser, (crayford type? looked like a mixture between that and rack and pinion) did not do anything. The
secondary was totally trashed also.
We gave our all of a sudden not so happy with his barter deal technician the bad news the next day. A day later he donated it to the "Eyes on the Sky"
The Restoration. When we took the 'scope apart we were shocked to see that the mirror had a "1961" date on it! WOW. I knew it was old,
but I did not realize it was one of the first commercially available 'scopes. We sent the mirrors to
Clausing, and had the standard Beral
coatings put on them. They came back flawless, and I would recommend them to anyone thinking of having a mirror redone.
The pedestal mount as mentioned earlier, needed considerable t.l.c. to get it working again. We never did get it right. We got the azimuth working,
but the latitude adjustment was rusted at 10 degrees and that was that. We took a quick poll around and decided to go with a Dob style mount, which has
worked out well for us.
The focuser was a bigger problem than it looked like at first. I could not find a modern focuser with the same amount of focusing range. I knew a rack
and pinion could be made to work if I took a hole saw to the fiberglass tube. I did not want to do this and further damage a beautiful old 'scope.
In the end I went with a low profile helical, and added a tele-extender to get the right focal length.
Under the stars, this telescope really shines now. It really is nearly the equal of my 10 inch f/6, a 'scope I have been told by many who look through
it, has Zambuto like quality. Planetary detail is excellent. Deep sky is just great. I find myself surprised over and over again by this telescope.
The figure on that primary is just excellent. We did not touch what the original guys at Cave Optical did with the figure, we just recoated it. I
reviewed this 'scope on the Todd Gross astro equipment ratings site, and I'll tell you now what I said then. If you like vintage 'scopes and you
don't have one of these, try to find one. You won't be disappointed!
Submitted by Edward Conley - email@example.com
- North Branch, MI