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Posts Made By: David Simons

September 7, 2002 12:45 PM Forum: Equipment Talk

high quality gem goto for imaging?

Posted By David Simons


What's the criteria for goto? Many of the CCD pictures I see posted are familier and easy to find Messier objects. Some of the best performance / dollar for sturdy mounts I would say are the previous generation AP QMD 900 and 1200 mounts. They include digital setting circles, which would make finding even dim objects fairly easy.

Are you thinking about automated sky surveys? Or minor planet tracking?

David Simons

November 7, 2002 09:33 PM Forum: Equipment Talk

refractor design 'simple?' question...

Posted By David Simons

Hi Andrew,

(Warning, hazy recollections of optics theory ahead, read at your own risk)

Although my copy of "Telescope Optics" is out of reach at the moment, from what I remember, one needs two glasses with quite different dispersion, or the ability of glass to act like a prism and spread white light into different colors. The key item was that if you had a low dispersion glass such as "ED" or fluorite, you could use almost any other common glass and get good color correction by adjusting the curves of each element. By carefully selecting the second glass, one could get really good color correction. If I recall, Lanthanum had some special properties (high refractive index?), but low dispersion was not one of them. So it may be useful to compensate for eyepiece aberations, but I don't think it would get you very far as a main element of the objective as compared to much cheaper glasses.

David Simons
(flame suit on)

March 13, 2003 10:20 PM Forum: Equipment Talk

Orion 120ST advice

Posted By David Simons

>>I'm considering buying an Orion 120ST as a rich field, grab and go scope <<

I ordered the OTA only, and fortunately had some 115mm rings and dovetail to mount it with. I can't speak for the mount Orion offers with it. I use a heavy duty Samson Tripod with a good vertical lift. This really is a grab and go setup. I keep it all setup in my den with the ep. installed, and grab it and go when the seeing looks good. Since this is alt-az, I also bought a pnumatic (sp?) stool that adjust in height. This is actually fairly important since it is so easy scanning the sky with this setup, and being able to quickly adjust the hieght is really needed. I am thinking of getting the Williams 45 degree Amici diagonal to match the views in my charts and binoculars. I also stole the rightside up finder from my ST80 which makes star hopping much easier.

I tried this OTA at ~100 power and really felt like the scope was working hard. Although the moon will still hold up at these powers. It really likes about 24-60x.

Orion now ships this scope with much better packaging, so the delicate collimation should stay tight. I have dark skies and really enjoy my ST120. However, if you are a city dweller, then the wide fields might not help you as much, as the sky glow will be fairly bright.

David Simons

June 12, 2003 10:42 PM Forum: Equipment Talk

Burned on an Astromart deal

Posted By David Simons

Hi Vincent,

As a side comment, I have had similar issues with UPS, I now insist any kind of significant Astromart deal be shipped Fedex, either 2nd day, or ground service, and have not had a shipping problem since. They also deliver on saturday, which is very nice.

I also think the right approach is to try to return the scope, once you get your money back and offering to send it at your expense seems like a reasonable compromise. Involving UPS can only complicate things moreso.

Another option,might be having the repairs done at Texas Nautical? Maybe the seller may be willing to fund that effort instead of a full refund? Hopefully the Astromart rating system will help move your situation to a reasonable conclusion.

Something I would like to see on the Astromart Home page is guidelines for packing and shipping a few kinds of common items (double boxing for instance) and some hints for doing transactions, and resolving conflicts, maybe some kind of "handshake" contract that both parties might agree to that spells out contigincies before any monies or goods are sent.


David Simons

July 11, 2003 06:52 PM Forum: Equipment Talk

Bino scope long baseline?

Posted By David Simons


If you could somehow combine these two images so the light wavelengths were in phase, I suppose that would give some of the benefits of a larger effective diameter, but then only in the one dimension, the other dimension would still have only a 4" resolution. However a persons eyes do not have the ability to discern light phase information, but only the intensity of the light, so the added 12" of separation of the two 4" lenses would not add any extra resolution over the 4" all by itself. However the brain has the ability to do some signal processing on the two seperate images and the binocular image will usually look better than a single view through one eye alone.

David Simons

August 28, 2003 07:18 PM Forum: Equipment Talk

Astroview 120 f5 vs 120 f8.3

Posted By David Simons

Hi Pam,

Virgo fuzzies need dark skies.

Can you see much of the Milky Way from your observing location naked eye? If there is a lot of Milky Way, you should be able to pick up a lot of the Virgo fuzzies at around 30X if there is not much sky glow in that area. If no Milky Way, then you will most likely need more aperture. I routinely see many of these objects with my ST120, but I run at around 25X, if your can get 30X the brightness should be fairly close.

David Simons

September 9, 2003 02:39 PM Forum: Equipment Talk

Big AOP or Dob help pick!

Posted By David Simons

The 12" Mewlon Mars picture on Anacordes "Image of the Day" was pretty amazing. I'd say the 250mm, or 300mm Mewlon's are good contenders as well.

David Simons

September 13, 2003 10:27 PM Forum: Equipment Talk

Astonished & Disappointed - Please Comment

Posted By David Simons

Hi Gary,

Great posting. A lot of hobbies have a sort of "Kings new Clothes" mystique to them. Astronomy and it's equipment maybe more so. I just turned 40 this year myself, and did my first observations back in grade school with a homemade 50mm (2") refractor scope that used a lense from the condenser of a projector and the mount was from my grandfathers old surveying level, I taped my tube onto it. (Yes it's a true story). I was not really expecting much with such a humble setup. Yet I was amazed at the craters on the moon, also the rings on Saturn, and the red spot on Jupiter was very red back then. I have gotten back into the hobby about 10 years ago, and now have a 16" Dob, (along with a few other scopes : ) and I enjoy finding faint fuzzies, yet there is nothing to compare to a school kids excitement seeing the planets for the first time. So perspective has a lot to do with it.

>> I think my $5k will be going elsewhere.
I purposely omitted the location because I didn't discuss my comments with the people present last night - I don't want to hurt anyone and if any of the individuals present last night reads this I intend no disrespect <<

I could not agree more. Spending $5K on ones first scope is like buying a $5K best set of skis, poles and bindings before you really know how and where to ski. Likely to be some disappointment here. I think your friends who bought the equipment are very satisfied with their scopes, and would be interested in your viewpoints, but I do not think they would be offended.

Astronomy, like skiing is not for everyone. But I really would recommend trying it again in a more favorable time or location, your friend will tell you when.


David Simons

September 18, 2003 05:28 PM Forum: Telescope Making

Two plate primary dob mirror?

Posted By David Simons

Hi Mark,

I actually have one of these mirrors, 11". It is physically made well, but I have not had a chance to look through it yet !!!!

Anybody else have one?

David Simons

September 26, 2003 11:35 PM Forum: Equipment Talk

100mm apo refractor or giant 20/25/40x100 binos?

Posted By David Simons

Ultimately I think many people would enjoy 25/150 Fujinon binoculars to go w/ a 16" dob and a 6" AP refractor, and of course 50 million other scopes. I forgot where I was going with this...

Hi Don,

You're right, that makes for a really good combination !!

Although a C14 works well in this mix also : )

One binocular that I have recently started enjoying is the very wide angle "Outsider" from Orion. Not top of the line, but really has a wide view (9.4 degrees), that gives a perspective on many targets before the big guns are used.

Also any binocular will seem to work much better when it is mounted, either using a tripod, or on a parallelogram setup. It is a good way to breath new life into bino viewing.

Bino Fanatic ....

David Simons