Omega Centauri

[jase]

Now have my mount tracking reasonably well (+/- 1.2 arcsecs), but still experiencing optical issues with the Lumicon GEG. Its simply not made to handle large format CCD cameras such as the STL11k. Strange considering it was made for 35mm film. Pixels are more discriminating than film grains.

Anyway, finally got around to some quick imaging...
http://www.cosmicphotos.com/gallery/starclusters/index.php?path=./&page=0&img=NGC%205139%20-%20Omega%20Centauri.jpg&idx=1

After selling the Astronomik LRGB 50mm unmounted filters more than a two months ago, I should finally have the Custom Scientific HaLRGBC 50mm unmounted filter set early next month. Looking forward to some colour imaging again and trying different combos such as (R)RGB, (Ha+R)RGB etc etc.

Thanks for looking. All comments welcome.

[Ric]

Very nice image Jase, it very nicely resolved.

Cheers

[iceman]

That's a fantastic image, Jase! Great resolution and well processed.

[Phil]

nice shot Jase sharp.
Phil

[h0ughy]

looks like its coming after me, great stuff

[jase]

Thanks for the positive feedback guys. :thumbsup: Still on a learning curve.

[leon]

Jase that is sooooooo good, it really is a beautiful object to image.

Leon

[Striker]

Looks great Jase,

I know what you mean regarding the Lumicon GEG, its probably the best way to reduce your focal length considerably then anything else on the market. but still not ideal.

What configuration you running the GEG.

[jase]

Hi Tony,
I predominately run the GEG in F/5.5 mode, but find I still need to bin 2x2 to get decent results. No binning results in ~1.2 arcsec/pix, a resolution I would rarely achieve from the observatory location - perhaps twice a year if lucky (and only when all planets are aligned and the wind is blowing in a westly direction at 10 knots).:lol:

F/4 delivers really nice views, but vignetting is too extreme on the STL11k. I've taken some flats to correct this, but seriously its not acceptable. The quantity of image processing through reduction/calibration is clearly not worth the effort in restoring the image. In particular, I found after the dark and flats are applied I still see gradients. I've taken multiple flats at a 30% pixel well count saturation (approx 15,000 for the KAI-11000 chip) and sigma rejected them. I know the flats and darks are of good quality and match the imaging train profile well, but it does not clean up the images as much as I'd like. Don't get me wrong, I could spend hours post processing to restore them, but I don't think thats ethically right. There comes a point where an image is too processed and not natural.

I've never tried F/6.5 as I don't feel the focal reduction is enough, but does depend on the object you intend to frame.

Ultimately you are right, from a SCT focal reducer perspective it is one of the best around. There are other options such as those from Optec http://www.optecinc.com/optec_026.htm, however I've never used one. I've heard the AP telecompressor is fantastic - http://www.astro-physics.com/products/accessories/photo_acc/photo_acc.htm#2
but again have not tested one.

Thanks for the feedback.:thumbsup: