Posts Made By: Doug Scobel

Ooh! Ahh!

Dmitri, here's an article on the subject I wrote for our club newsletter a little while back. It relates my experience. Hope you find it useful. (The title was supposed to be "Can You Do It?", but the webmaster who posted it to the site used the wrong text.)

Doug

http://www.umich.edu/~lowbrows/reflections/2003/dscobel.11.html

Here's my homemade 13.1" f/4.5 workhorse, with my homemade observing chair. Just add eyepiece and observer!

Doug

And here's my 8-inch f/8 I built for the Mars opposition of 2003.

Doug

Didn't the Okie-Tex SP used to be held at a different site every year? I even heard that it has been held at the Prude Ranch (TSP site). Is this true? Do they still do that? I've been to the TSP, would love to see the "other side of the universe" from there in the fall!

Doug

Justin De Guire said:

I was calculating the true field of view for each of my eyepieces using this formula.

True Field of View = Magnification / Apparent Field of view

Example 32mm Plossl with 50 degrees of apparent field of view
Scope’s focal length 1250mm.
1250 / 32 yields a magnification of 39.06. Plug the magnification into the formula above.
1.28 = 39.06 / 50 True field of view is 1.28

I think that this is inverted. The way you have it, the higher the magnification, the larger the true FOV. It should be:

True Field of View = Apparent Field of view / Magnification

You were actually doing this in your calculations and didn't realize it. 8)

Best regards,
Doug

Yeah, I see what you mean. I'd be embarrassed to post a picture like that - NOT!

Gee, can't wait to see a "good" one!

Best,
Doug

With a Zambuto primary and only 50% more $$$ for the good secondary then it would be a no brainer for me. I think you've answered your own question, Floyd. Go for it. 8)

Doug

Growing up in Detroit in 1969, when I was 14, a neighbor from across the street, his name was Ed Kondratko, came over one day and asked me if I would like a telescope. I’m thinking to myself he’s talking about one of those cheap little 60mm refractors. So I tell him “sure”. He goes and comes back, wheeling (what I considered at the time) a HUGE, homemade 6-inch f/8 reflector, on a heavy duty machined pipe mount. It was complete, with eyepieces, Norton’s Star Atlas, S&T magazines, mirror making materials, Edmund Scientific books, and a copy of Allyn Thompson’s “Making Your Own Telescope”. Well, complete, except there was no primary mirror. The story was that he had spent countless hours building everything, and making the primary mirror. He was in the final figuring stage, and while attempting to star test it uncoated in the telescope before sending it to the coaters, he dropped it and broke it. He didn’t have the heart to start over, so he gave it all to me, figuring I could maybe make use of it. After reading through Thompson’s book umpteen times, I made my first mirror in my garage that summer. I was working alone with only the book to guide me, so it ended up at f/9, couldn’t get the curve deep enough. But it came out decent enough, and the first two things I looked at through it were the Moon and Saturn, arguably to two most spectacular objects you can look at. I couldn’t believe my eyes! Needless to say I was hooked, and the rest is history.

I’ve long since rebuilt that scope, so that little of the original remains, but I still have it. In fact, I still use that pipe mount for my 8-inch f/8 “Mars Scope” that I built for the 2003 opposition. Making good use of that mount made me think of Ed, wondering what had happened to him, since I had not seen him in more than 30 years. He probably had no idea what his selfless act meant to me, so I looked him up on the Internet, and wrote him a letter. I explained to him where that scope and the others that followed have taken me, and all the wonderful sights I and others had seen through it, and that I owed it all to him. In his reply I learned that he had fallen on some hard times, but he was extremely gratified that something good came out of his gift. I hope to keep in touch with him in the future. He definitely “paid forward”, and for that he has my gratitude. Thanks, Ed!

Doug

Wow, Floyd, that's some kind of feat! Congrats, sounds like you've got one great scope there.

What magnification(s) were you using? What eyepieces?

Doug