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Posts Made By: David Simons

April 15, 2004 08:26 AM Forum: Deep Sky Observing

How Many Galaxies in Bill's picture of the day?

Posted By David Simons

Aside from 2.

I looked at the image full scale, and was amazed how many fuzzy little galaxies were hidden in that image.

David

April 26, 2004 01:42 AM Forum: Telescope Making

First Light For TT2 (Turret Telescope 2)

Posted By David Simons

I finally got enough pieces together to do a decent first light test of my version of the Turret Telescope at Stellafane.

Earlier post:

http://www.astromart.com/messages.asp?message_id=189733&page=

For comparison I also used a Tak 152 f8 refractor for a fairly reliable bench mark : ) I only did a quick star test, also Jupiter and the Moon. From what I could tell, the two big mirrors on the TT2 were taking their sweet time cooling down this eve. Slow undulating wavery views, with sometimes very fine detail on the moon and Jupiter. The star test was not really showing any rings, just a symmetric donut with a very small hole out of focus on either side. But the good news was no discernable astigmatism, as this was a concern since the main steering mirror is not exactly a "flat" but a >very< long focus spherical mirror. Sorry I'm not really a star test evaluator yet : )

Collimation was intuitive. A laser down the focuser tube was aligned to hit the center of the parabolic mirror and return into the focuser. With the big cutout in the side of the OTA it was clear what needed to be aligned. Cooling will be the next hurdle in this design !

My wife and three year old son wanted to see what Daddy was spending all afternoon doing : )

The Takahashi did not seem to have the same cooldown issues. The same level of detail was usually present most of the time in the Tak, but the really detailed views did not seem to pop into view very often, as the TT2 occasionally did. The Tak showed nice diffraction rings on either side of focus, with a slight amount of purple on one side of focus, and a good hard sn-a-p when it hit best focus with no extra color. Powers were ~60/48,169/135 and 250/228 for the TT2 and Tak respectively. Eyepieces: Vixen silvertop plossl, and Pentax ortho 9,6mm.

I suspect the views I had through the TT2 are similar to what premium dob owners are getting, but without the spider diffraction effects.

Comments welcome !

David Simons

May 13, 2004 12:55 AM Forum: Antique/Classic/Vintage Optical Instruments

RE Brandt Lens

Posted By David Simons

I have an 8" doublet ~f13 that looks to be a Brandt lens from the early 80's. Has anyone used or looked through one of these lenses?

Thanks,


David Simons

June 3, 2004 08:16 PM Forum: Equipment Talk

C8 on a pier mount

Posted By David Simons

I couldn't resist trying this as I had an adapter that happened to mate the two pieces together. Even though the sidereal tracking is only in azimuth, it still held Jupiter in the FOV for a few minutes at about 60X with small adjustments to the altitude control. Not a lot better than pushing a dob, but was some improvement.

Anyway, I thought it looked cool.

David Simons


June 3, 2004 09:28 PM Forum: Equipment Talk

RTMC: Celestrons Big one

Posted By David Simons

I never got a chance to look through Celestrons new C20, but I think it lives up to their new motto pretty well.

David

June 7, 2004 09:45 AM Forum: Equipment Talk

Wide Field Viewing

Posted By David Simons

Had some fun scanning Cygnus last night with a Meade 10SN and wide field 80mm Flak binoculars. I got tired of assembling the GEM mount for the 10" when all I wanted to do was do was a little star hopping.

I was inspired at RTMC by a simple pipe mount I saw and wanted something simple for the 10"SN. So, $35 and an hour later, and I was set. The SN amazes me with the sharp wide field views it gives. I wish Meade would do a 12 or 14" version smile

David Simons

June 7, 2004 03:19 PM Forum: Telescope Making

Correct Image Newtonian

Posted By David Simons

I was going back and forth between my wide angle 80mm flak binoculars, my Meade 10"f4 SN and the star map, and shifting views between the correct view bino's and the inverted Newt started driving me crazy. Does anybody know how to get a correct view out of a Newt and still keep a wide field? I'm using a 27mm Panoptic, which is about perfect or this scope.

David Simons

June 14, 2004 08:20 AM Forum: Deep Sky Observing

Veil at last

Posted By David Simons

I finally managed to see the Veil with a pair of 10x80 binoculars last Saturday, the left side was the brighter, and looked very much like the picture. The top star is Epsilon Cygnus.

Knowing exactly where to look made a big difference.

David Simons

July 8, 2004 12:58 PM Forum: Telescope Making

Modified Red Reading Lamp

Posted By David Simons

OK, not strictly telescope making, but I had a little but of fun putting this together. I was about to toss out an old unused weighted stand reading lamp, when I thought how handy this would be if it were usable at night. Well a quick trip to Radio Shack for some red 12V lamps, and a 12V outlet plug, and I was in business.

David Simons


July 15, 2004 08:59 AM Forum: Equipment Talk

Sky-Watcher 150 f5 refractor

Posted By David Simons

Sky-Watcher 150 f5 refractor

I just received this scope a few weeks ago, and finally had a chance to use it a little.

Mechanicals: Very front heavy, I had to remove the heavy dew shield to get it to balance on my Quickset photo tripod. The scope is heavier than it looks at around 13lbs, and is really the limit of this tripod. The tube without the dew shield is very short. It almost does not look like a "classic" refractor. I like this OTA format, as tilting the tube does not require too much raising or lowering of the tripod. The coatings were OK, a little brighter than I would have liked, not stunning or nearly invisible like a Tak or AP. No streaks or anything like that, just a little bright. The lens cell is not adjustable (see concerns below) The focuser is a typical 2" Synta type, lightweight, but functional. The lens cap has a nice large secondary cap that gives about a 4" opening for better color correction at the expense of aperture.

Optical: To cut to the chase, the views are sharp, but start to show color after about 75X. I was very nervous the collimation would be off since the lense cell is not adjustable, but the in and out of focus images were nice and round, so far so good. I tried to get diffraction rings, but could only get a hint of such things around 125X, the highest power I tried that night. Other refractors I have used such as a Vixen 4" f9 fluorite showed a beautiful 1st ring around 200X. Since I really bought this as a wide field scope I wanted to know if I could get tight star images at the 25-60X range I was planning to mostly use this scope at. No problem here, I used a 27mm Panoptic which gave a stunning 2.4 degree 27.8X wide field sharp to the edge view. The stars focused to pinpricks and many dim little stars popped into focus at the sweet spot. The Cygnus region was filled with stars and large clusters. The bright side of the Veil was obvious without a filter. One of my favorite large open clusters, NGC6940 near the veil was glittering with faint pinpoint stars. I wanted to see where the scopes color error was starting to be objectionable, and at around 100X, the purple halo starts to be fairly obvious. I tried to reach Vega, but the tripod I was using did not want to reach the zenith, so I settled for Deneb. Stars were still very sharp at this magnification.

A scope like this is kind of a niche instrument. It allows for sharp very wide bright field of views. Big clusters and star clouds are it's game. Large dim structure that is only hinted at in binoculars become star filled swathes of sky. Extreme low powers like this sometimes don't work as well with similar size newtonians, as the secondary mirror needs to be full size to get good field illumination, and the obstruction can start showing a shadow at the lowest powers. The Sagittarius region will be a treat this summer. These type of scopes may be for the refractoraholic only, but I am curious to see how wide a field I can get before my exit pupil starts to clip the entrance aperature. Anybody have a 35mm Nagler ? smile

David Simons