47 TUC Issues

[peeb61]

Hi All,
I was wondering if anyone could shine a bit of light on this issue?

My target was 47 TUC of various exposures, started off with 20s, 30s, 40s and 120s and when my run was finished grabbed darks using same exposures.

To combat light pollution in my area I have included a you beaut 2" LP filter to the imaging train.

I ended up with 172 light subs of various exposures.

When all light subs including new darks and on file, flats and bias frames stacked in DSS, most of the 20s and 30s were rejected due to not enough stars to detect even though I changed the value to 2%.

The debayer matrix is set to my camera, QHY8L.

The attached image is a stack of 66 subs excluding the 20s and 30s, totaling 1 hour 3 minutes and processed in photoshop.

Any ideas why the image comes up a bit on the red side?

To combat light pollution in my area I have included a you beaut 2" LP filter in the imaging train.

Many thanks in advance.

Paul

[morls]

Was this image taken with the Mak-Newt? I came across these online the other day, and they look pretty good...

[Startrek]

Paul
I image quite a few globs but with a DSLR ( pixel size 4.3uM ) and I’m under Bortle 8 skies
I don’t use any filters either
I never stack different exposure lengths in DSS , never have
Same exposure and same ISO
Here’s my settings in DSS
Don’t know if this helps at all
For processing I only use Startools and get a great result every time

Raw Files / Fits Digital Development
Raw files tab
White Balance
Uncheck both “use auto white balance” and “use camera white balance”
Bayer Matrix Transformation
Check Bilinear Interpolation
Leave Set the black point to 0 box unchecked
Fits files tab leave blank or unchecked

Stacking Parameters
Tick use all available processors in all tabs
Result check Standard
Light tab check Kappa Sigma clipping
Dark tab check Kappa Sigma clipping
Flat tab check Median
Alignment tab check Automatic
Intermediate Files check Fits
Output tab tick create output file, check autosave tif/fits , tick Append a number to avoid file override, check Create output file in the folder of the reference frame

In Stacking Steps
RGB Channels Background Calibration - No
Per Channel Background Calibration- No
Register Settings Advanced Tab check “Reduce noise by using a Median filter

Good luck and hopefully others will comment with some help
Cheers

[peeb61]

Yes Stephen it was taken with the Mak-Newt, lovely imaging scope, I have a lot of successes with it in my old house but now I have moved and a new set up? Having minor problems with my imaging camera?

[peeb61]

Thanks Martin will check mt DSS setting and have another go...should I stack all of the 120s and then 40s etc separate with darks etc and then do a stack at the end of the different exposures into one final exposure?

Thanks for you help with the settings...much appreciated.

Paul

[peeb61]

Well Martin,

I think your settings for DSS worked! :thumbsup:
Attached is the 120s version with darks and flats, 20 subs totalling 40 minutes worth. I think its come up a lot better?

Many thanks

Paul

[LostInSp_ce]

That looks much better Paul even colour and with a nice flat background that hasn't been clipped too hard. In my experience, using multiple exposure lengths in DSS is a recipe for disaster. This is because each set of exposures needs to have accompanying calibration files with the same ISO/Gain values. Best to stack your exposure sets individually and then combine them later. There are programs that can handle 'mixed bag' data sets but unfortunately DSS isn't one of them.

[Sunfish]

Looks like you have lost the colour. The stars in Tuc should be blue or yellow white. I am not sure if LP filters add a little violet which might be part of the problem and you need to balance that out. Perhaps others know more than I.

I also find that sometimes background colour balancing is required in DSS to help get the colour sorted out if you are stretching in DSS before exporting to PS.

Also if you are stacking, run a registration with all subs ,choose the one with the most stars and right click to make it the reference file rather than letting DSS pick one, and check all your subs one by one zoomed in to make sure there are no very bad ones.

[Sunfish]

Ps . But generally much better and almost got that colour .

[peeb61]

Thanks LostInSpa_ce, its a lot better than the first one published so I have taken a couple of steps forward thanks to Martin, I will do what you say stack individually and see what this yields...many thanks for your input most appreciated.



Thanks Ray, whenever some sort of DSF is involved there is always going to be collateral damage of some sort probably in this case the lost frequency, filters as we know don't take away LP but they may help, I will however remove the filter on the next run and see how it pans out, at the moment its a bit of trial and error...street lights v dark skies.

I never do any sort of processing in DSS, I just grab the 32bit and export into Photoshop.
Also thanks for the tips in DSS. :thumbsup:

[Startrek]

Paul
Glad to see your images are a lot better now
I don’t alter my image in DSS once stacked , it’s saved as a fits file and loaded straight into Startools. Startools requires clean linear data to be able to perform at its optimum level

Cheers

[peeb61]

Thanks Martin for your valued help in updating me with the settings for DSS, I thought I was going mad, didn't matter how many times I uninstalled and reinstalled it would always find the config files and update the unwanted settings....Now? I'm happy again.