clear sky chart

Job 9:9

Job 9:9-10
9 He is the Maker of the Bear and Orion,
the Pleiades and the constellations of the south.
10 He performs wonders that cannot be fathomed,
miracles that cannot be counted.
NIV

Saturday, March 19, 2011

Refractor Building Underway

The lens arrived from Surplus Shed Thursday, and I went to a local surplus dealer today and bought some 5" OD aluminum tubing.  I bought 48 inches, but I really only need half that.  I got extra in case I mess up, which is a very good possibility.

The lens is real nice!  I was surprised by the quality vs price.  These lenses are an excellent deal.  I got the 127mm / 700mm fl lens.  I went with the short focal length because I feel it would be a great moon scope as well as a planetary one for photography.  Also, I do believe it will actually ride on my cheapie equatorial mount.  I have been having trouble with the longer telescopes and the webcam, having a tad too much magnification, so I thought this size would work out nicely.

I tend to get into too big a hurry when I start building stuff.  This was no exception.  I actually got a lot done in just one day.  I got the tube filed down so it fits the objective, cut the tube to rough length, and painted the inside flat black.  Here are the 2 pieces.  Remember, this is a 5 inch, short tube refractor.

The tube still needs primed and painted on the outside.  Being I dont have a machine shop,  the end where the objective goes looks a little rough, it looks worse than it is.  I'm almost certain that a coat of primer and white paint and the rough filing wont show through.

And yes, it does fit together so far:

I laid this assembly outside on the porch bannister and aimed this across the highway and into a treeline about 1000 feet away and held by hand, a low power eyepiece, and the trees appeared close and sharp.  Not a bad first little test.

Of course there will be more pictures and stories as I continue with this project.

5 comments:

Doug said...

Looking good so far. I do a lot of this too, mostly 60mm size.
Your right, the paint will cover the file marks.
I know! LOL

Doug76

desert said...

I have the same lens and made a similar telescope. It works but the stars have huge blue halos around them due to chromatic aberration. I even used two 127 mm lenses from surplus shed (1200mm and 700 mm) in a Petzval arrangement and got better results but still pretty big blue halos on stars. There are minus violet filters that might improve the halos, but I haven't tried these yet.

-Edward Little
edlittle@yahoo.com

Mike H - KD0AR said...

Noted... I'll watch for it. I will probably try it out tonight in limited fashion. I just installed a home made focuser, and waiting for the epoxy to dry. I will be buying something better, but...im in too big a hurry to try it out! (no baffles yet either.

I'll write another story later today

Ed said...

Mike, Where did you buy 5" OD aluminum tubing?
I've searched all around Los Angeles wit no results. Need 2.5, 4, 8" thin wall.

Ed

Mike H - KD0AR said...

Ed,
I got it from a company called "Star Supply" in Youngstown, OH., about 10 miles from where I live. It is a surplus store, so their stock varies. They had perhaps 10 pieces, 10 feet long when I bought my piece. They will cut it for you, so I got 48 inches for about $20. Their website is at http://www.starbarg.com/index_test.htm

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