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Posts Made By: David Simons

January 20, 2008 10:11 AM Forum: Equipment Talk

Tinsely 8" Cassegrain Type

Posted By David Simons

Hi Folks,

Does anybody know whether the old 8" Tinsley cassegrain was a "classical" or some other variant.

Thanks !

January 20, 2008 10:12 AM Forum: Antique/Classic/Vintage Optical Instruments

Tinsley Cassegrain type

Posted By David Simons

Hi Folks,

Does anybody know whether the old 8" Tinsley cassegrain was a "classical" or some other variant.

Thanks !

January 20, 2008 10:18 AM Forum: Telescope Making

Tinsley Cassegrain type

Posted By David Simons

Hi Folks,

Sorry if I have repeated this post too many time in other forums, but the granularity of the forum headings is getting pretty fine these days.

Does anybody know whether the old 8" Tinsley cassegrain was a "classical" or some other variant.

I have what I have been told is secondary from an 8" Tinsley.

Is there any simple way to test such a cassegrain secondary mirror to check if it is hyperbolic or spherical ?

Thanks !

June 22, 2008 02:34 PM Forum: Equipment Talk

Meade 10in SN focuser replacement

Posted By David Simons

Hi Folks,

I was looking at the new Orion two speed focuser. Any thoughts if this would work on the 10"SN ?

Or any recommendations about replacement focusers? I would like to do some basic photography, and the stock unit seems a little flimsy.

Thanks !

July 14, 2008 10:54 PM Forum: Telescope Making

Another 8in Refractor

Posted By David Simons

I've had this 8 inch f10 doublet lense from the Ukraine sitting around for almost a year, and finally have gotten the parts and time to put it all together.

Although first light was last weekend, there is still lot's more to do, painting, anodizing, baffles etc.

The glass has a very slight light tan color, which has helped reduce the violet fringe. However the visual images are everything an 8" refractor should be. Pinpoint stars, and detail on the moon that just seems to keep going and going. I have not been much of a double star viewer, but this scope may change all that. grin

August 28, 2008 12:28 AM Forum: Deep Sky Observing

Tracking down the Big Game

Posted By David Simons

Hi Folks,

I'll be at a dark sky spot this friday (Sonama Lake for you N. Cal. folks) with some big binoculars. I hope to track down some of the large open clusters. I'll be looking at the likes of M23,24,25,IC4756 and NGC6633 around the Sagittarius, Scutum and Serpens area.

Any other suggestions for some big open clusters ? wink

(picture borrowed from: http://www.allthesky.com/constellations/scutum/constell.html)

January 30, 2009 12:16 AM Forum: Deep Sky Observing

Clusters of Clusters

Posted By David Simons

Jan 29, 2009

A moderate 39F temp. near Santa Rosa, one hour north of San Francisco. At 10:30pm, seeing was about a Mag 4.8, with the Little Dipper stars directly visible, but with a slight haze, as the lights from jet airplanes would show a projection beam ahead of them. Targets were clusters, some nebulas and a few galaxies. I hadn't used my 8" f6 cardboard tube refractor since last fall, and had to dust off the mount, but the scope and lense were still in fine condition from their slumber in the garage these last few months. One of these days I will get around to painting the tube.

I tuned up the 30mm finder while observing M42. Can't go wrong starting a winter observing session with that. I then tried for the Rosette Nebula and would probably need the OIII filter. I was right, only the 6 bright stars of the inner cluster were obvious, but with the filter in, the giant hazy donut started to appear around the ladder of stars. This nebula is really big, I was viewing about 2 degrees FOV, and I still panned around a bit to catch it all. This would really be a treat at a truly dark sky site.

Jumping down to the Canis Major region I proceeded to cluster-hop starting from M50 in Monoceros down to NGC2335, 2343, 2345, left to 2374 and the truly awesome M46,47, and NGC2423 trio of clusters. All three were almost fitting into the FOV. The beautiful contrast of the carpet of fine small stars in M46 compared to the clumpiness of the bright stars in M47 always give me a smile. I then searched out the lone big cluster of dim stars M48, and further north to M67 and on to the giant Beehive cluster which just fits in the widest FOV of the 8" short tube refractor.

I swung over to Leo to bag a few of the bright galaxies. M105, 96, and 95 nestled in the dim "square" in the middle of Leo. These three required a bit more magnification to tease out from these not too dark skies, so they did not quite all fit the same FOV. But the ovel shapes were tantalizing glimpses of the Messier / Galaxy season yet to come. NGC 3384 came along for the ride as well. Moving to the Leo Trio M65,66, and NGC3628 in the back "Leg" of Leo always makes for a fine sight in the same field of view. Wrapping up, I swung over to the double cluster, and then ambled over to cluster M103 in Cass., which to me has a dual personality. It was just starting to show the cluster of fine stars stars behind the few bright stars. I continued a bit farther with the clusters NGC659, 663, and 654, again nearly fitting in the same field.

This was a fine night of clusters of clusters and groups of galaxies. Looking forward to Virgo and a proper Galaxy tour in the next few months !


March 16, 2009 12:00 AM Forum: Reflectors

Ronchi Test of an unknown mirror

Posted By David Simons

Hi Folks,

I just received a 16" f1.2 mirror that I think is supposed to be spherical. It has a large central hole with an epoxied on aluminum mounting flange.

I recall a spherical mirror would have straight lines in a Ronchi-gram ?

Any thoughts on what is going on with this mirror ?

Thanks !

May 27, 2009 10:35 PM Forum: Pictures of Me and My Telescope and........

Red Tube Coulter 13.1in - Final demise

Posted By David Simons

Hi Folks,

My red tube Coulter 13.1" dob was just getting to be too heavy to lug around, and the mirror is destined for a truss someday.

My wife just got some cats and was threatening to buy a $100+ cat climbing condo.

What would any telescope builder do?

The big red tube was a natural choice for this application. wink

June 22, 2009 10:39 PM Forum: Pictures of Me and My Telescope and........

Re: apo fetish

Posted By David Simons

Wow !

What's the story on the lense ? Curious minds just wanna know : )

[COLOR="Blue"]
david goldman said:

here's one scope that takes care of aperture envy.
[/COLOR]