Image of the day

Captured by
RICHARD COFER

VdB 141 Ghost Nebula

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Posts Made By: Roland Christen

June 15, 2007 11:15 PM Forum: CCD Imaging and Processing/Deep Sky

NGC6888 wide field

Posted By Roland Christen
Here it is in color. I used the new Baader narrow band filters of Ha, O3 and S2. Exposures were 60 min for H-a, 30 min for S2 and O3.

Rolando

June 15, 2007 11:48 PM Forum: Astro-Physics

NGC6888 with 140mm refractor

Posted By Roland Christen
Here is a color version, taken with Baader narrow band filters, Ha, O3 and S2. 1/4 size.

Rolando

June 20, 2007 03:18 AM Forum: TeleVue

UFOs in my TV-85?

Posted By Roland Christen
I saw it too. Thought it was two airplanes at first until I realized that it was out in space.

Rolando

June 25, 2007 06:06 PM Forum: Bad to the Bone Autos

I coulda Had a Mewlon 300

Posted By Roland Christen
Hey, you got the light red version. Very nice (I have the dark "Merlot" version of the GT). I really like mine - great performer for the money.

Rolando

June 29, 2007 10:08 PM Forum: Refractors

17 Years in the making

Posted By Roland Christen
Nice work!

Rolando

July 3, 2007 07:33 PM Forum: Astro-Physics

NGC6888 with 140mm refractor

Posted By Roland Christen
I finally was able to get a decent night to try all 3 of the Baader filters. In processing I tried to combine the colors in such a way as to get more natural coloration. This shot uses H-alpha for red, O-3 for blue and an average of H-a, S-2 O-3 for green. This shot shows the full view of the camera with the 140 operating at F5.7, image reduced to 1/4 size.

Rolando

July 3, 2007 11:12 PM Forum: CCD Imaging and Processing/Solar System

Jupiter, June 23 from Murrumbateman

Posted By Roland Christen
Aaawsome!

Rolando

July 5, 2007 07:34 PM Forum: Astro-Physics

PEMPro for Mach1GTO

Posted By Roland Christen
The Mach1 is identical in all ways to the 900 mount.

Roland Christen

July 6, 2007 02:40 PM Forum: Landscape Photography

Lava Flow, June 2007

Posted By Roland Christen
SUPER!

Rolando

July 7, 2007 12:51 AM Forum: CCD Imaging and Processing/Deep Sky

Network Nebula (false color)

Posted By Roland Christen
You scope has coma and you also have some tracking/guiding issues. You cannot normally elimiate coma in a refractor by simply adjusting the collimation, i.e. the tilt of the lens cell. That's because refractors are designed with zero inherent coma, therefore adjusting the tilt of the lens cell will not allow you to introduce opposite coma to compensate like you can in a Newtonian. All that will likely happen is that you will introduce astigmatism when you tilt a refractor lens. The one exception is a Petzval, which must have the front lens accurately squared on, otherwise there is massive coma.

Coma in an airspaced objective arises either with poor homogeneity in one or more of the elements, or improper spacer thicknesses around the perimeter. Therfore, to really fix it requires very careful adjustment of the three spacers. Some refractor designs allow you to move the rear element sideways to cancel out the coma, but this actually adds a small amount of lateral color to the image.

Rolando

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