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Posts Made By: David Simons

November 6, 2009 11:05 PM Forum: Refractors

optics mavens needed

Posted By David Simons

Hi Greg,

I have been pushing for an optics forum for years.

Maybe someday.

Heck, I'll even help moderate it !!

November 22, 2009 08:21 AM Forum: Telescope Making

Memorial service for John Gregory

Posted By David Simons

Hi Kurt,

Thanks for passing the news. I got a chance to briefly talk with John during lunch at the 2006 RTMC. He was giving the lecture on Optics and Optical Design: "My 60 Years of Astro-Optics"

It was amazing all the cutting edge projects this fellow had designed and worked on.

About the nicest guy you can imagine also.

Kurt King said:

We have lost a truely great man. John has passed away after a car accident and Carolyn is in very serious condition. Posted is memorial information:

I can't remember if I told you the plan for an open informal memorial service for John at Lake Travis UMC (Lake Travis United Methodist Church is at 1502 RR 620 North in Austin) this Saturday, Nov 21st at 3:00pm. The sons and family of John would love to have all that touched or were touched by John's life to attend and meet them.

The sincere hope is for a formal memorial service after Carolyn's recovery but Johns sons and family need to have this service at this time.

Carolyn is still in serious condition and in need of prayers.

Would you be so kind as to share this with the local astronomy group and any others you can think of. A notice of service will be posted in the newspapers.

Thank you so much for all you are doing.

love you and John,


November 27, 2009 12:11 AM Forum: Telescope Making

Mirror making

Posted By David Simons

HI John,

Thanks for sharing. For those of us not too Focault literate, maybe you could give some pointers at what's going on in the picture.

Thanks !

January 27, 2010 11:03 PM Forum: Telescope Making

Periscope accessory for Newtonians

Posted By David Simons

Hi Dick,

There was a telescope design I heard of that created a collimated beam by using a special curved secondary. The scope I think was called an Afocul Mersenne. There was a fellow in Texas Clyde Bone, that essentially "relayed" the afocal image down to the bottom of his 20" dob, then re-imaged the parallel light with a refractor. His main concern was being able to sit down while viewing.

I recall hearing there was some unusual effects with this design, one of them was a lot of field curvature.

I have tried some simple relay experiments, and found it was possible for a newtonian to give a correct view image !

If Vladimir is still around, he could give you some concrete info on any pitfalls to this idea.

Dick Jacobson said:

I am building a periscope accessory that will attach to the side of a big Newtonian to lower the eyepiece height. Does anyone know if this has been done before? I've heard of a periscopic Newtonian that was spotted many years ago at the Texas Star Party.

May 4, 2010 09:53 PM Forum: Reflectors

another mirror cleaning problem

Posted By David Simons

Gary Klein said:

I accidentally got a little silicone adhesive on the front surface of my 11 inch flat (part of a diagonal for a large scope).

Gary Klein
Hi Gary,

If you don't mind me asking, what kind of a scope needs an 11" diagonal ?

: )

June 26, 2010 12:29 PM Forum: Refractors

Intane Optics "Beware" Do not buy!!!!

Posted By David Simons

Hi Bobby,

For what it's worth, I have an 8" f6 lens from Intane. I did an auto-collimation Ronchi image of the lense, and while not perfect, was very reasonable for the type of wide field viewing I was planning. About 100x is as high as I go. It is one of my favorite scopes for dark skies.

Although I did not have a problem, your experience makes one think twice about any future deals.

July 3, 2010 09:10 PM Forum: Refractors

Short tube vs. Long focal length refractors

Posted By David Simons

Hi Robin,

Curious why you want a refractor?

Your previous description sounded a lot like a C6 OTA. smile

Getting back on topic, I have a Burgess 127 f8 ( a good one) and although the focuser is marginal, the optics are killer.

July 21, 2010 03:22 PM Forum: Equipment Talk

"C14 is a Small Scope" (The Movie)

Posted By David Simons

Hi Greg,

Great video!

I am a bit of a C14 rebel, and use an alt-az mount.

Although it's a bit crude, it is very portable. I use rings for the C14 which reduces the scare factor of mounting the scope.

I have also tried rings on an AP900 and although it needs a lot more counterweight, it pretty easy to mount ht e scope that way also.

See scroll down a bit for the C14 mount.

May 14, 2011 10:51 PM Forum: Telescope Making

Sand Blasting large mirror blanks for web structur

Posted By David Simons


Another option, although seems far-fetched is machining with diamond tools to get the web pattern.

I have seen this done on very expensive low expansion conical blanks.

Didn't say it was cheap, just possible. : )

August 6, 2011 11:07 AM Forum: Refractors

80mm preference

Posted By David Simons


The old-school Celestron / Vixen 80mm Fluorite works for me.

These Vixen Fluorites don't seem to understand they are just 80mm scopes. They take crazy powers on the moon, planets and double stars.

John Whitby said:

Explore scientific, Stellarvue Svr80 ED, or Orion ED80T CF?