[Solved] Unusual Integration Blotchy Areas

Would you mind telling us what solved it? 🙂 Could be valuable for others as well. Thanks!

Hi Vincent

Actually, I found out what caused the problem but not sure if I can fix it.  The did two objects one night after the other using the same setup and using the same flats and dark flats.  The remade the flats and dark flats both using NINA and SharpCap just to see if a change occurred.  They are all identical as I am in a permanent setup and no equipment was touched.  The Bubble Nebula histograms of both Ha and OIII look normal as I stretch them but the ones from the Little Dumbbell do not stretch properly.  The midtones level, when moved to the left, responds as expected but as I start to move the black level from left to right, the # of clipped black pixels jumps to the thousands.  It does not behave as a normal histogram stretch.  My APP settings are the default ones and have always worked and my NINA settings were the same for both objects.   So, I am at a loss as to what caused this.  I guess I must wait for another clear night and take more images and see if the same problem occurs.  If you have any ideas, I am all ears.

Interesting. Did you maybe mix data from both packages? That can cause issues.

@vincent-mod

No- I was careful to separate both data sets but something is clearly wrong with the calibration of the Little Dumbbell data.  I was able to get a somewhat decent image by just aligning and integrating the lights without using the darks, flats, and dark flats.  Yet, the same darks, flats, and dark flats all worked perfectly on the Bubble nebula.  I can’t understand what could be causing this.  Hopefully, I will have a clear night on Sunday to run more lights and see what happens.  

It appears my dark frames might be the problem and a friend seems to be confirming the same thing.  My darks are taken at the same temp and exposure as the lights.  I dither every third light frame but not the darks.  When both of us process my data without the darks, they are noisy but the image looks normal and so does the histogram.  So, could this be the problem and how should I fix it? 

@umasscrew39 Dithering has no influence on darks because darks don't involve light and are independent of the orientation of the optical train or camera. Did you take the darks with the same software as the lights? If not then that's the cause. 

Good question- no, not always.  I never thought of it as a potential problem as I was using SharpCap but moved to NINA and darks were made with SC or NINA while lights, flats and dark flats with NINA.  Thanks for the tip.  I need to recheck and probably re-do all of these.

Finally resolved!!!!!!!!!!!

I trashed all of the darks, dark flats and flats and re-did them using NINA.  Collected new lights with NINA.  Ha sample of the Pacman nebula. 

and it worked perfectly.  Thanks again for the help.