Omega 2

[Peter Ward]

Not that the world needs another Omega Cent, here is my Easter rending (http://www.atscope.com.au/BRO/gallery539.html)under a full moon. (rare clear skies required a quick imaging fix...sorry no colour)

Still getting my head around CMOS imagers and to my amazement this image shows absolutely no CMOS banding which,
while a great result, I can't explain given the camera settings were identical to that used in my RC.

The 3.7u pixels seem to be an excellent match for the 820mm FL of the AP130...
Roland Christen at AP has clearly waved his magic wand over the field corrector...pristine stars to the edge. :)

[Zubenel]

Crisp!. I can't figure which PGC galaxies you have captured but I can see at least two. Nice one.��

[Startrek]

Beautiful Omega !!
Pin point perfection from core out to the edge of frame
A joy to view , well done again

[JA]

Super sharp image Peter :thumbsup:

I was interested to see no low level banding as you mentioned it last time and hey presto ...none. Did you dither the exposures? Any different USB cables, interfaces, hubs or ports used?

Best
JA

[Peter Ward]

I wish I could say I changed up something.
Not a thing.
Dithering still used, same , same etc.
One of life's mysteries :shrug:

[JA]

Hi Peter,

Whilst you didn't change anything, except for the optics* of course, I re-read your initial post above and it dawned on me that the sky possibly changed significantly between your two images.....

As mentioned in your opening post above and your original Omega thread,
your Omega 2 image with the AP130 was imaged under a full moon, whereas
your Omega image with the RC16 was imaged under a rising moon.

Depending on the difference in the moon's phase and position in the sky during both of your images you could potentially have seen anything up to 2 to 3 times more sky background illumination (I've estimated this based on an SQM difference of ~1 to 1.5 between Full moon and no or partial moon). This extra illumination would have been collected by the sensor and possibly pushed it into a more comfortable zone where no or less banding is present. I suspect if there is any difference in overall illumination, it would show in a comparison of the exposure histograms from raw subexposures of the Omega & Omega 2 images. I do feel that the whites are whiter in the Omega 2 image so there may be something to it, but that's just my visual comparison and the images posted aren't raw so not sure. It would be interesting to know to help with the mystery.

*edit
There is a difference in the focal ratio between the 2 optics which might come in to play: f/6 and a 60(?)mm Image Circle for the RC16 with Reducer versus I think f/6.7 and a 65mm Image Circle for the AP 130GTX with AP Flattener. These differences should in fact favour the RC16's light collection per unit area. This advantage does not seem to be evident, given the low level banding on the original Omega (RC16) image versus none on the Omega 2 (130GTX) image. This to me, even more, suggests a difference in sky illumination as the possible reason why one image shows banding whereas the other does not.

Best
JA

[multiweb]

Nice quickie Peter. Top notch :thumbsup:

[leon]

Yea I suppose its alright, :eyepop::P, bloody hell I thought the first one was awesome, so what is the adjective for this one, or cant we say that on IIS. :shrug:

Just a bit of fun, excellent work indeed Peter, beautiful and crisp all the way through.:thumbsup:

Leon:thumbsup:

[Peter Ward]

Ta Leon, Marc. I am about to go on a short vacation, hence needed a fix
before we set sail.



I think there is some merit to your argument. I suspect a very dim sky background will reveal CMOS banding which is masked with a smidge more sky signal. More investigations required....

[spiezzy]

one of the best omega's i have seen for a while well done Peter
cheers pete