Lagoon RGB attempt

kinetic (Steve) · #1 03-05-2009, 01:17 AM

Hi ,
tonight the seeing enabled me to try 10 second
exposures instead of my usual 5 sec ones.
But this time I didn't go mono, I tried a quick set
of RGB on the Lagoon.
No sharp luminosity was used here, just purely RGB.

Steve

jase (Jason) · #2 03-05-2009, 08:28 AM

Good effort Steve. It helps to shoot basic RGB to get your colour balance correct before adding luminance to the set. Often luminance with throw the colour balance out, hence its important to know what your working with. In this instance your green channel is heavily black clipped which is resulting in the strong weighting of magenta. You may need to weight the green channel higher and/or in post processing keep an eye on the histogram as you go through the routine. Keep at it.

kinetic (Steve) · #3 03-05-2009, 08:52 AM

You know what Jase, it looks terrible now on the inside LCD!
It looked quite respectable and not so grainy on the Dome CRT
last night.

The object of the exercise last night was to see what filter
factor I had to add to get the RGBs to match a 5sec Lum
if I ever get that far.
It seems like 10sec is a good start point because it didn't
need too much extreme stretching to bring all that out.
When I did a 5sec RGB set the other night it was only after
a great deal of stretching that very noisy data came out.
All of my data, as you can imagine with 5 and 10 sec subs
is all way down the black end of the histogram.
It's still there though...god bless CCD dynamic ranges!

It's only because I do LOTS of exposures that I make the
noise floor drop away and leav a clean data set.
On warm nights I battle with more noise obviously, so a
very cold night with excellent seeing and this camera/ 12" newt
performs.

I did do an auto 'colour offset adjustment' and it made the colour
seem very natural. But that was at the expense of some
contrast. When I fire up the dome PC today I'll dig out the
RAW RGB combined FIT and post it here for comparison.

Thanks Jase so much for the encouragement!

Steve

kinetic (Steve) · #4 03-05-2009, 06:10 PM

Now here with the auto colour offset applied.

Steve