Frustrated...going backwards

[Pscm]

Soul final.JPG (349.31 KiB) Viewed 6966 times

IC1848 AD.JPG (207.09 KiB) Viewed 6966 times

In recent weeks I have upgraded my DSLR to a Nikon D5300 and started guiding using an ASIAIR setup and scope is an AT 80MM triplet. All of this is fine operationally. The other night I went after IC1848. Ran 20 subs at 5 mins each, dithered and 15 flats. Until recently I was doing darks as well but trying to get a good library is hard with a DSLR and it seems dithering is the way with a DSLR from some research. I am shooting in a bortle class 3 area. The attach pics are snips of what the first auto dev looked like and the final after noise reduction. I understand that i have over done things but I can't seem to pull any detail out of this. I also ran into this with the last image I shot. I have upgraded both DSS and ST and am using the no white balance option. I have not checked the camera as of late to see if I have mucked up a setting. I am also pulling fts files directly from the ASIAIR. Looking for some suggestions on where to start. I have had some pretty good images in the past although I now regress.

[Burly]

If your dithering then you can take bias frames you only need to do it once ,take 50 then when stacking load these bias frames into the Darks tab don't reload into bias frames tab ,also bear in mind the camera is not modded ,what iso are you using the d5300 is iso invariable and the suggested iso is 200 info here http://dslr-astrophotography.com/iso-va ... n-cameras/ ,funnily enough i have just started using an unmodded D5300 i use APT for acquisition and dither 16 pixels when you load image into startools it gives you image size so mine reads 6016 x4016 hence im dithering 16 pixels ,i have never tried the soul nebula so i would not know what to expect with 2 hrs of data using an unmodded camera but star colour looks great to me you could try the life module and see if you can lift anymore out .

regards dave

[admin]

Hi all,

The significant halos around stars and low signal almost make me believe we are dealing with extremely poor transparency or simply dew.
If that definitely was not the case here, then your AutoDev result shows something wrong with you flats, causing some sort of "inverse" vignetting. Try stacking without the flats and see if your signal improves.

I'm optimistic it's something simple!

[Pscm]

Thanks for the input. With the AIR the most I can move is 5 pixels although not sure if that is a true 5 pixels or some variant of that. I can see a definite apparent shift between frames so I suspect 5 may be much more but I don't know. Have never thought about the bias to dark concept but I like it. I will try tonight to stack just the lights and see what happens. I am pretty sure it was not dew. If anything it would have been frost . I run dew heaters on both my guide and main scope. Both of my last image serious were at locations that should produce red although I am not being able to pull it out. I have seen some others that have imaged the soul nebula with an unmodified camera and it looks so much better than this. The only thing I have changed up is not using darks. The nikon has so much less noise than the canon I was using and being that darks are such a pain related to a dslr that I was trying a different route.

Will report back.

[Pscm]

So I started xshooting potential issues. My flats are between 1/3 & 1/2 on histogram. They could stand to be closer to the 1/2 area if I understand flats process. I am shooting at ISO200. I also noticed that the first 10 pics have quite a bit of glow if you will and then got really dark. I processed without flats and it seemed to remove the Inverness that was showing although not able to pull hardly any color out of it. I would say since I got the D5300 my pic quality is lacking from the cannon which shouldnt be so as there is much less noise. Wonder if something in the camera is set wrong. I am shooting 12 bits. Any suggestions on the best settings or where to go?

Also if using the suggested bias concept, do I need to dither those as well?

[admin]

I also noticed that the first 10 pics have quite a bit of glow if you will and then got really dark. I processed without flats and it seemed to remove the Inverness that was showing

Ok, that is significant - any ideas why this might have happened? Consistency of signal is incredibly important...

[Pscm]

Not real sure. Could have been atmosphere or maybe scope hadn't cooled. Not really sure.

[Burly]

Re flats I use a light panel ,I noted what the exposure should be using A mode then in APT set a plan up with that setting , re settings on camera i just made sure everything was switched off in menu settings .

Regards Dave

[Pscm]

For Admin, I have another question. With ASIAIR on this last imaging session I decided to pull the pics from the ASIAIR versus the camera. The AIR converts my Nikon NEF to FITS files. So in DSS does checking the "No White Balance" have no effect because they are now FITS files and if this is the case what option would I select for the type of image when first loading into ST?

[admin]

For Admin, I have another question. With ASIAIR on this last imaging session I decided to pull the pics from the ASIAIR versus the camera. The AIR converts my Nikon NEF to FITS files. So in DSS does checking the "No White Balance" have no effect because they are now FITS files and if this is the case what option would I select for the type of image when first loading into ST?

Hmmm... that depends on what AIR has done during the conversion. When you open the FITS files, say in StarTools, are they still mono and do they still have a Bayer pattern in place? In that case, they will not have been white balanced, nor will DSS white balance them (which is good!). In that case, you can choose the second option in StarTools when importing the final stack DSS has made.

If AIR, however, has done its own debayering while converting to FITS, then all bets are off...