Posts Made By: Ron Harper

My wife recently remarked that her IPOD has developed a taste for Stevie Ray Vaughn. She means, in the shuffle, supposedly random-play mode, she senses a systematic behavior.

I'm a dinosaur myself, and put on the record I want to hear, but I got to wondering, can you put Go-To into a shuffle mode? If you could do that, and select easy, medium, or difficult objects, it would make a fun game to look in the eyepiece and guess what was being viewed. There might even be a way of interpreting the objects pointed like Tarot cards, as an indication of your personality, or future, or a message from the sky. Could this be the next phase of Astrology?
Ron

The other night, with the moon 9hrs past first quarter, I was looking through a binocular, and to my surprise that I saw the old moon. I had never noticed it so late in the cycle. I tried again the next night, and saw it again. Then, last night, with the terminator past Copernicus, I at last could not see it. On all three nights, conditions were extremely clear and dry, at 7400 feet elevation, and the moon was well up in the sky.

Have you moon observers seen the old moon late in the cycle? I wonder what's the latest its been seen.
Thanks,
Ron

It has been nothing but clouds and rain here in northern NM all this spring and summer. My D&G 5" f/12 has set there on top of its wooden post, on its 2 inch "pipe mount" equatorial, with only a fake-leather cover over it, for MONTHS now, without use. 6 years, total. Maybe I have no respect for optics, I don't know. Tonight it was clear!

No big deal. I removed the weights that keep the scope stable in the wild winds we get here. I flipped her upside down, and slipped off the cover. Pulled off the lens cap and inspected with a red flashlight--no insects or mold, just the speckles of dust that have been there for a long time. Installed dew shield, flipped the scope towards the sky, put in the 7mm ortho, pointed at Alberio, finder still set perfectly. Seeing average good. Pointed at delta Cygnus. Nice spilt! M13, with an 18mm, with averted vision, nice spray of delicate points! Etc. I hadn't used a scope in so long I was pretty rusty, but it sure was nice to see my old friends again.

This is no hotshot report of observing at the edge, just a reminder that metal and glass, and nothing else, makes a tough mother of a telescope, that will stand what the earth dishes out and be there for you. Waltz out, and see, no fooling around. This is one of the advantages of refractors listed by the old books, and it's the truth.
Ron

I became aware of this website, containing some of the coolest old telescope catalogs, over on CN, and thought you would enjoy it if you haven't seen it already.
http://geogdata.csun.edu/~voltaire/classics/

Of special interest is the 1987 AP catalog, containing an comparison of the color correction plots of an achromat, Roland's early stuff which managed without fluoride glass, and an early fluoride model. There are also mentions of other aberrations. This one takes a minute to load, but hang on I promise it's worth the wait.
http://geogdata.csun.edu/~voltaire/classics/ap/ap87.pdf
Having pretty much mastered H. Dennis Taylor"s "The Adjustment and Testing of Telescope Optics", this looks to me like the dawning of the New Age.

Actually, I'm still getting along just fine with my 5" f/12 D&G, permanently mounted in the backyard on my homemade "pipe mount" from 1970. But it's not like I'm "In Denial"-- I just don't know what I'm missing, is all.

Happy Holidays,
Ron

The Cambridge Deep-Sky Album, by Jack Newton and Phillip Teece. You will need averted vision. Just beautiful. It was published in 1983, but you might find a copy used from Amazon or Alibris.

Herbert,
Your terse, dense post captures the magic of observing like Walter Scott Houston did in the early Sky and Telescope years. This is the essence of how we send our narrow beams of intelligence from desolate places, walk about the galaxy, and try to make some sense of an infinite universe, first hand, in our short time. It makes me want to get out there. Thank you.
Ron

Walter,

Typically, achromats are single coated with MgF2, which increases the transmission by 3% per surface. So, even if the coating looks terrible, if the wear and tear is only on the outer exposed surface, the transmission loss is insignificant.

A more important problem is the phase shift difference between rays that pass through 1/4 wave thick coating and those that don't, where it's missing. You don't really want an extra 1/4 wave error added to any fine lens. For that reason, if a lot of the coating is gone, say 25%, (which would look outrageously horrible under a bright light) best-resolution has been slightly compromised.

The up side is, if that much coating came off due to natural causes, it can't have been that good in the first place, and it probably will not require abrasives to remove the rest.

Ron

Everybody,
I guess this small chapter in the war of the refractors is about over, and I'd like to thank all who participated. I learned something from every post. There wasn't a bit of Apo snobbery or Achro defensiveness. Everybody listened, not just talked. Nobody got really silly, except possibly me. You are a classy bunch of guys.

I started the thread wondering if I should upgrade from my 5" f/12 D&G to an apo. I love that color curve jazz, but it is not like sharing real experiences. While more convinced than ever of the visual superiority of the Apo, I am also convinced that, compared to my present scope, it's a rather slim margin. Slim enough to live with. I will stick with what I've got for awhile. Hey, simple eyepieces are great at f/12!
Ron

Osvaldo,
I use a Rigel Quickfinder on the upper tube assembly and a widefield eyepiece to sweep up objects that I know right where are. I also have a 12x80 straight-through finder mounted on one of the poles at a comfortable height. It is good for star-hops(though harder to use than a wider field 8x50), and for nice views of large things, and will reveal Messiers and brighter NGCs at a dark site. It's pretty cool to put the crosshairs on the Crab Nebula and then climb up the steps!
Ron

Robert,
Fellow refractor ardent Rob Wiederich has some kind of raising and lowering pier for his 6" f/15. I'm sure he'd tell you about it if you got his attention or wrote him off-forum. I have seen survey instruments that cranked up and down with a rack and pinion arrangement that would be nice for your scope. Of course you still have to have a good neck for near-zenith viewing, but it would get the strain off your back and legs.

It seems I have read that the Japanese straight-through observers think looking up reduces the amount of "floaters" seen on bright planets at small exit pupil. I've never tried it, but I have noticed that I can control my floaters better in some positions than others, so there might be something to it.

Ron