Omega Centauri revisited

Post by **rcj** » Wed Jan 11, 2006 9:39 pm

Hi,
Something back, I posted a picture of Omega Centauri taken by a DSLR. Back then it was one single raw image. I have tried processing a collection of images of Omega Centauri again. Here it is, one normal version and another that is cropped and zoomed closer to see the cluster. The characteristic light glow from the camera on the top left of the image has been corrected, and the core was processed so as to make sure it is not washed out (from my monitor!). The series of subframes were all taken using the Epsilon210 8-inch hyperbolic newtonian with the Nikon D70. Exposures ranged from 4minutes to 6minutes at ASA200. Manual guided with G11. Let me know how it looks. This is the first time I am processing a DSLR image, and I am trying to get away from the framework process method of film images....
Oops! BTW, this was taken at the same Desaru location spot where the star parties for ASTROFOCUS2006 will be held.

Post by **rcj** » Wed Jan 11, 2006 9:40 pm

here is the cropped version

Post by **rcj** » Wed Jan 11, 2006 9:40 pm

Here are some other DSLR images:
http://www.geocities.com/remuscj/imaged ... e_dslr.htm

ariefm71 · Post by **ariefm71** » Wed Jan 11, 2006 10:05 pm

OMG!!! that E210 is really something!

Jeremy · Post by **Jeremy** » Thu Jan 12, 2006 5:30 am

Crikey, Remus - that's a splendid image! Wonderful resolution right to the centre.

Go well!
Jeremy

Kamikazer · Post by **Kamikazer** » Sat Jan 14, 2006 1:26 am

hi, remus

is it me or does the core look blurry or soft? whereas the edge of the cluster appeared sharp.

Post by **rcj** » Sat Jan 14, 2006 6:32 pm

hmm....looks fine on me monitor...

Jeremy · Post by **Jeremy** » Sat Jan 14, 2006 7:35 pm

....think it's only an effect of the large number of stars in the core. You tend to get the same effect visually. But in fact it's just as sharp in the centre. I always struggle to get the centre of globulars looking good (i.e. without being burnt out) in my CCD images, but this is an excellent example.

Go well!
Jeremy

boothee · Post by **boothee** » Sun Jan 15, 2006 9:27 pm

Beautiful one!

Post by **rcj** » Mon Jan 16, 2006 1:29 am

Hi everyone,
Been trying the Omega Centauri image again, but this time in colour rather than grayscale. Please let me know how it looks from your monitor, as I processed this image entirely from my old PC laptop which I think the display might be a bit off. Time to get a better monitor soon!
Previous attempt shown on was done based on grayscale image. Also no darks were used, purely a vignetting background profile extracted from the primary image of the globular cluster. I went on to take a series of dark frames again today, and also some flat frames plus bias frames, and combined them together and subtracted them from the original image of the cluster. This is definitely a more "orthodox" method and the colours result is more accurate. I have also tried to make it more film like, and try not to overexpose the core again by resampling the image thrice based on the same image. I did not take separate shorter exposures of the cluster to prevent the core from overexposing. Alternatively, I took the lazy-man's approach (through curves in photoshop and varying the opacity) to get the resulting image attached here.
And this exposure is only all based on a single 335seconds ASA200 image.

Can't wait to gather more 335seconds (or so) light images of the cluster and do a further combine to lower the noise more...