Stripes in stacked Image

[SirSocket]

This is a stack of several 4 minute exposures at ISO 800. The individual images look fine and don't seem to have these sort of stripes in them, but after stacking they show up and ruin the shot. After reading on here a bit I figured it might be because of a lack of dithering? I did not use guiding with this image, so should I need dithering? If so, how can I dither without guiding?

These stripes also show up on shorter exposures by the way.

 

Gear:

Camera: Canon EOS 200D/SL2

Scope: Samyang 135mm f2

Mount: Skywatcher EQ5 Pro

 

[upahill]

I used dithering to get rid of that noise on my Canon. Not sure how it would be done without guiding other than just a manual teeny nudge every few subs. How are you capturing, perhaps the software has the option? From what I read with a quick google BYEOS and APT support dithering without guiding. Not sure about others though.

[toxic]

did you use flats and or darks if so then try stacking without them and see what happens some times bad flats or not enough flats can cause this and if its darks then you need a lot more.

if that dosnt work when stacking use median as the stacking method.

hope this helps

 

[david_taurus83]

You can dither without guiding via APT but you need to have it connect to the scope via EQMod.

[alacant]

On 14/11/2019 at 19:51, SirSocket said:

dither without guiding

Hi

Turn off tracking for a while in between each frame. Make the time that the mount is not tracking random, up to say 15 seconds.

Tell us what you are using to capture frames and we can be more specific.

Cheers and HTH

[vlaiv]

I've seen this effect number of times before and still have not figured out why it is happening. I know it is related to read noise - but not sure in which way.

You say that each of your subs on its own is fine when stretched?

How about aligned subs before stacking, do they show the pattern? It could be that this pattern is created from read noise by alignment process (if bilinear interpolation is used or something like that)?

[SamAndrew]

That looks like walking noise caused by a small dift between each frame. Dark frames should subtract it provided you take the darks at the same temperatrure as the light frames. Dithering would work too.

[Gerry Casa Christiana]

The way I resolved this issue on my Canon 550d (almost) is by removing the SD card out of the camera. Someone on here Carol if I remember correctly suggested I try. Since then I don’t keep a SD card in. I believe it’s a electronic signal being picked up in the frame. Give it a try

Gerry