Newbie wide field astro help!

[purplepanda]

Hello! im new to this forum, apologies in advance if the threads in the wrong area. recently, i took 33 images of the milky way, untracked, just simple images and stacked them in Adobe photoshop using a median filter (oly ep3). however, in my final image i get a lot of vertical banding, like purple streaks running down the image. Ive tried using DSS but with the same result. does anyone know what i should do? this is my first try at astro stuff so i have no clue. Should i try doing background calibration in PixinSight? I've uploaded a compressed image for you to see. im not expectingg a perfect image, but hope to at least recover it. im relying on you guys!!   p.s. i realise that the streaks appear in the single frames as well, so obviously it was my fault in the first place

[wxsatuser]

It looks like vertical banding but may be 'walking noise', it follows the way the stars trailed.

Which camera and settings?

You have a fair bit of distortion bottom right and some chromatic abberation, this is most likely the lens used.

 

[purplepanda]

1 minute ago, wxsatuser said:

It looks like vertical banding but may be 'walking noise', it follows the way the stars trailed.

Which camera and settings?

You have a fair bit of distortion bottom right and some chromatic abberation, this is most likely the lens used.

 

Thanks for responding! I'm using an ageing Oly Ep3, with a 14-42mm  kit lens. Settings I'm pretty sure were f3.5, iso 2500? Or 2000, 20 seconds for each frame

[wxsatuser]

Have you tried a Sigma clip stacking?

You should have some natural dithering with static shots, may be worth a try.

If it's vertical banding, Pixinsight has a tool that might remove it or there is an action in Astronomy Tools Actions by Prodigital

[purplepanda]

Yep, I'll try dithering next time. With the Sigma clip stack method, which would you recommend, median Kappa sigma or Kapa-sigma? I barely know anything about this stuff. Thanks so much for the ideas! Really appreciate it

[wxsatuser]

Try both and see if it helps.

Try some dark frames, it may help with noise and will also subtract the bias.

[ronin]

No idea if it will help but I would drop the ISO to around 800 even 400. Cameras after a certain setting tend to boost the noise too much and it may be that 2000 is too high. They may have the setting but that doesn't mean they work well at it. Also I am used to iso on film and I am sure that the ISO on a DSLR does not correlate across, sort of same term slightly different action.

Have you taken a few dark frames? Easy to do and they again can help and with DSS they are not too difficult to include. Not exactly as simple as they could be I find but once you get the idea they go in happily. Just another fairly easy option to throw in the mix.

[purplepanda]

30 minutes ago, ronin said:

No idea if it will help but I would drop the ISO to around 800 even 400. Cameras after a certain setting tend to boost the noise too much and it may be that 2000 is too high. They may have the setting but that doesn't mean they work well at it. Also I am used to iso on film and I am sure that the ISO on a DSLR does not correlate across, sort of same term slightly different action.

Have you taken a few dark frames? Easy to do and they again can help and with DSS they are not too difficult to include. Not exactly as simple as they could be I find but once you get the idea they go in happily. Just another fairly easy option to throw in the mix.

Hey Ronin, thanks for the ideas! I think I started off trying low ISOs but found the image way too dark on my camera screen. Wouldnt this be a problem? And sadly, with all the excitement looking at the MY I totally forgot to take the darks...  But does this meant his image can't be salvaged using software?

[spillage]

Hi,

I would drop your iso to a maximum of 1600 and maybe then try dropping it more. I didnt see that you mentioned bias and flat files. I would use these with your lights and then experiment with the darks. You may find not using darks helps.

cheers

Spill.