Globular Clusters

TrevorW · #1 10-04-2010, 05:41 PM

Tried for a couple of globulars last night second light with the QHY8

M4 in Scorpius is a loose globular

1hr 1min 8X6 and 13X1minute subs some darks no flats or bias

probably needed longer subs on this just couldn't get the colours I wanted

NGC2808 in Carina is a dense globular over a million stars

1hr 37min 10x6min 11x2min 15x1min some darks no flats or bias

C&C

duncan · #2 10-04-2010, 06:42 PM

Hi Trevor,
The first one is my pick. On my monitor it exudes a lovely golden hue.
Look forward to more.
Cheers,
Duncan

TrevorW · #3 10-04-2010, 07:03 PM

Thanks Duncan I wasn't happy with either I've reworked NGC2808 with only the 6 minute subs and thinks it's an improvement

duncan · #4 10-04-2010, 07:10 PM

Hi Trevor,
I'm not familiar or cant remember this Glob. So i'm assuming that it must appear small visually. Does this explain the resolution into the core?
The repro is definately more appealing.
Cheers,
Duncan

multiweb (Marc) · #5 10-04-2010, 07:43 PM

Quote:

Originally Posted by TrevorW

Thanks Duncan I wasn't happy with either I've reworked NGC2808 with only the 6 minute subs and thinks it's an improvement

Yeah that's a hot shot! Well done.

TrevorW · #6 10-04-2010, 08:13 PM

Thanks Marc here is a rework of M4

I think when stacking the varying exposure length FITS files in DSS it degrades the image. Probably better of doing individual stacks on each exposure length and then combine in PS

toryglen-boy (Duncan) · #7 10-04-2010, 08:27 PM

Good to see you up and running on the QHY8 mate, great images, although they look a little clipped, or posterized maybe

thanks for sharin

trick · #8 10-04-2010, 08:43 PM

Quote:

Originally Posted by toryglen-boy

Good to see you up and running on the QHY8 mate, great images, although they look a little clipped, or posterized maybe

thanks for sharin

Duncan just wondering what does the term clipped mean? I have heard it a few times in here.

TrevorW · #9 10-04-2010, 09:04 PM

Hi Trick

Clipping is used to enhance features within an image. You provide a threshold level to determine how the clipping occurs. The values above (or below) the threshold level remain the same while the other values are set equal to the level.

In this case clipping can occur trying to get the background as dark as you can to remove such things as LP and make foreground objects stand out

NGC2808 isn' IMO clipped although M4 probably is as their was some severe LP in the top part of the image which I had to work out

hope this makes some sense

trick · #10 10-04-2010, 09:07 PM

Thanks Trev just learning the lingo

TrevorW · #11 11-04-2010, 10:19 AM

No problems I'm still learning