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Posts Made By: David Simons

July 17, 2008 06:11 PM Forum: Reflectors

Orion 3.6" off axis reflector on SALE

Posted By David Simons

Hi Darian,

Thanks for bringing this up. If I did not already have an off-axis telescope project in the works, I probably would have jumped on this, just to "try it out". I love exotic designs, and the price is right.

The picture is of a 4" thick Zerodur substrate large enough to make a nearly 12" f8.3 off axis scope. It is from a 1/3 "section" of a 25" f4 mirror. It weighs about 50lbs. I have yet to check to see if this is actually a parabola or spherical surface.

July 23, 2008 07:33 PM Forum: Equipment Talk

Walking in the footsteps of giants

Posted By David Simons

Simply awesome.

I will have to make the pilgrimage someday.

Thanks for sharing. smile


August 14, 2008 06:39 PM Forum: Telescope Making

Which better- holing a flat, or making a flat from

Posted By David Simons

Hi Jess,

The fellow who made my flat, bored the hole first, and the "plug" was held in place with wax I think during grinding and figuring. I didn't bother with having the hole bored at an angle, as the actual angle is fairly slight, although for a second mirror, I would try to have a slightly oversize flat, and the bore angle factored in.

Walter Scott Houston made a number of observations with the 12" Stellafane "Porter Turret" scope you reference that were written up in his observing columns.

I have some pictures of a scope somewhat similar to what you describe on my web page:

http://www.planetatm.com/

Scroll down a bit to get to it. I decided not to use a 45 degree angle, as the requirements on a 45 degree flat get very severe. One of the advantages to this design is how easy it is to get near "perfect" collimation, since you are looking essentially straight into the parabolic mirror. The images are not very Newtonian-like as there is no spider diffraction and the central obstruction can be made very small.

August 20, 2008 10:56 PM Forum: Telescope Making

26 inch F8 or higher

Posted By David Simons

Hi Jess,

Is this actually a decent flat mirror ? Have you tried to test it against any other known flats ?

It might be more useful as a flat, rather than a blank to be ground into a telescope.

September 28, 2008 10:17 PM Forum: Telescope Making

CCds for Celestron Schmidt Camera

Posted By David Simons

Sounds like a very interesting project.

Is there field curvature at the image plane ?

December 10, 2008 09:57 PM Forum: Equipment Talk

New pier in 20min

Posted By David Simons

Hi Keith,

Looks great as usual !

Any problems with minimum lengths ? Cutting fees etc. ?

I have the same mount but it needs a lot of work, serious rust removal.




May 26, 2009 09:41 PM Forum: Equipment Talk

If I only had one telescope.

Posted By David Simons

Hi John,

For me, I don't think the ideal <$3K scope has yet been marketed.

I am partial to lightweight, and aperture.

I would need some kind of carbon fiber / aluminum dob-style scope with a thin Quartz mirror ~14" diameter.

I've seen handmade scopes like this last year, and early in the evening Jupiter was showing about 8 bands with details, later we looked at the horsehead nebula with a Hb filter, it was standing out obvious.

The upper scope assy. without rocker box could be picked up with one hand.

Not sure if this could be built commercially for $3K, but this would be a lifetime scope for most of us I think.

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Jack Bruneau said:

I have been thinking about what the best general purpose astronomy telescope is under $3,000. Two of my lifetime favorites have been the Tak FS 102 and the TEC 6. I no longer own either and am in the market for the perfect general purpose scope. Any thoughts?
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June 22, 2009 10:36 PM Forum: Equipment Talk

What is your dream scope?

Posted By David Simons

Hi Keith,

As I am somewhat of a big bino fan, I think this fellow has the right approach. 8" lenses. : )

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Keith Lawson said:

I believe everyone has a dream instrument that is either beyond their bank account or is no longer made or a combination of other factors. So I ask: What is your dream scope and why? No professional observatories please.

Here is mine: A Questar 12. Optical and mechanical perfection! No GOTO but man what an instrument 8) As a lunar/planetary observer this would be an ultimate instrument. Now if I could have it and good seeing to match...
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July 3, 2009 11:59 PM Forum: Solar System Observing

titan shadow transit

Posted By David Simons

Hi George,

It was my first Saturn transit. I was using 270x with an 8" f10 doublet refractor, and 7.5mm Tak le ep. Seeing was fairly turbulent, with a few moments of steadiness. As I recall the small shadow was right up against the ring, it was a little tricky for me to recognize at first.



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George Golitzin said:

Anybody see the Titan shadow transit on 7/1? (UT 7/2, about 4:40) It was very nice in my 16", very briefly, before the fog rolled in during late twilight. The shadow was on the northern edge of the A ring, about 45 degrees in from the eastern limb, while Titan itself was just NW of the planet, even with the pole. I used 375X.

--geo.
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August 30, 2009 09:45 PM Forum: Telescope Making

New Tripod Spreader

Posted By David Simons

Hi Bill,

Great Job !

Thanks for posting, I'm hoping to get inspired and try it.

David


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Bill Byrd said:

[COLOR="Purple"]Sorry! Read my posts from the bottom up. I did them as individual posts to keep from having extra pics all over the place and the posts are backwards now. Confused?
Bill[/COLOR]
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