Pelican Nebula WIP / Clouds, so time to experiment

[Menno555]

The Pelican Nebula
The Netherlands in Bortle 7/8

Every time great predictions for the nights, every time just clouds
So, busy with experimenting with processing on a set I am busy with: the Pelican Nebula.
Had some troubles with my camera but after contact with Zwo, an uninstall and new install of Zwo drivers, it works fine again.

This my first time at an object like this ... and I am loving it!
This is with the Optolong L-Pro. Going to gather more data and then after that with the Optolong L-eNhance and blend all that together.
There is more blue in what I have now but I need more data to work with that.
Also done some star reduction for the first time. Bit hard because of my long focal length (2032mm) the bit bigger stars have streaks.
And last but not least: a lot more calibration files. Especially going from 20 to 100 darks had an impact: there was rather a lot of horizontal banding but that's almost gone now. And I did the darks during the day: in a dark room with covered scope and camera at -10 degrees Celsius and then, while having a coffee (or 2), just take the darks. And also the (dark)flats at -10 degrees since I was busy anyway.

And any tips on capturing these kind of objects are welcome of course!

Meade LX65 8" f/10 ACF OTA
Ioptron CEM25EC mount (no guiding)
Optolong L-Pro filter
Zwo ASI294MC Pro camera

Captured with SharpCap @ -10 degrees Celsius / 200 x 60 sec / Gain 121 / Offset 30 / White balance R50/B50
Stacked in DeepSkyStacker with 100 darks + 100 flats + 100 dark flats
Processed in PS: Levels, (lot of) Curves, Shadows/Highlights, color strengthening, star reduction. Astronomy Tools actions: Contrast enhancement, noise reduction. Scaled down from 4000px.

Pelican_WIP.jpg (511.08 KiB) Viewed 1210 times

[Candieman]

I don't have much advice to offer because this is looking pretty good already (IMHO), but I do have a question concerning the camera settings. I see you used a gain of 121 and brightness of 4 in SharpCap. ZWO gives the "unity gain" for the 294 as a gain of 120 with a brightness of 30. How did you decide on 121/4, and do you know how much of a difference it makes to images to use 121/4 rather than 120/30? Also, for color balance you use (R)50 and B(50). Everything I see from ZWO shows R(52) and B(95), How did you decide on 50/50 (which I believe sounds better than using 52/95)?

Candieman

[Menno555]

Hi Candieman

Thank you.
The brightness is an error, I did use 30.
As for the gain, 120 or 121 doesn't really matter. I just wanted to be on the safe side, so I did 121.
The color balance of 50/50 is the default setting in the Zwo driver itself. I don't know why in SharpCap that is set to 52/95. But I checked in the Zwo capture software itself and with default it's 50/50 and that works fine Disadvantage is that green is dominant then and with 52/95 it's more "balanced". But in both cases nothing that can be dealt with during processing.

The difference between the brightness/offset of 4 and 30 I can't really explain in detail. I do know that it has to do with black- and white level. I am still learning More info here: https://docs.sharpcap.co.uk/2.9/11_CameraControls.htm
For now I did use the default 30 and the values that I get with the Smart Histogram Brain tool for real captures. That can give for example 24 seconds, gain 121 and brightness 4. This all specific for my setup and sky at that moment.
And I experiment with values: I keep an eye on the histogram, make sure that my brightness is always above 1 and below 80, try different gain and exposure values. And then see what happens

Menno

[timh]

Hi Menno,

I have been admiring some of the pictures that you have put up. That is a great image of the Pelican. Lovely detail in the core. Better then the one I got a couple of nights ago using the same camera but a wider field F 560 mm picture.

The offset thing does seem to be a bit strange with the ZWO AS1294. The Sharpcap Brain recommends an offset (brightness) value of 4. For bright (5 e) skies it then works out that lots of rather short exposures are best. However - if you go right down to the 6 or 7s exposure time recommended and stick with an offset of 4 it just doesn't seem to work because then the histogram is right down on zero with for example at least one of the channels in fact within a standard deviation of zero. Therefore like you I set the offset to about 30 and then it all seems to work fine

Tim

[Menno555]

Hi Tim

Thanks!!
And yes, I have the same experience here with the 294: short exposures up to 30 seconds do work fine with the lower brightness/offset. But longer exposures simply miss out then with lower brightness/offset. The 30 value really works best then indeed.

And (finally) collected all the data I want on the Pelican. I have over 5 hours of data with the Optolong L-Pro and L-eNhance now and going to process and blend now. Don't know yet if I will make crop where the centre part is rotated to a horizontal plane and/or that I'll make it grey-scale. I did notice that in grey-scale it's all "easier" to view, there is no red color distracting your eyes and brain