DSS doesn't stack images nor align them

[Abbas]

Hello everyone

I have been struggling with deep sky stacker for a while now

The problem started when I tried to capture the North America Nebula, I took some frames (lights, darks, biases, flats) and everything was fine, I then tried to stack those frames but it says "only one frame will be stacked" how ever I tried some stuff like star threshold and I asked about it then I realized that my shutter speed was a bit high (2 seconds), so then I tried capturing with 1s of exposure and nothing's changed, the same issue is popping up, only one time it stacked some frames and the stars appeared "very" trailed, I never gave up and I tried for many nights and nothing works the same issue each time

But I remembered that I had some orion constellation pictures I've captured a while ago and I stacked them and it worked but with everything was Doubled, the Orion nebula, Rigel, Betelgeuse, some other stars, everything was Doubled

I guess the difference between the frames of the Orion and the frames of NGC7000 is that the first were captured using my phone normal camera, while the second were captured using an external app

Note : I use my phone I don't have a dslr

My equipment : Celestron SCTW-80 (other name Celestron Libra 80500 (it's a 80mm aperture and 500mm focal length telescope) and 23mm 62° eyepiece, and my phone which is Redmi 9, and a normal manual alt-az mount

I'm sorry for the long description but I really need help

[PeterCPC]

DSS can be quite fussy about images - if they are not in focus or star shapes are odd, then it will not stack.

I suggest that you upload here a single sub so that we can see what it's like.  Upload a png or jpeg.

[Elp]

Think you need to take a step back and go through it logically. As mentioned an uploaded image will help us assess.

I strongly suspect, even though you may think the images are fine, the stars are not round. Any elongation, star trail, coma will stop star registration dead.

Are you "checking all" frames, then going into "register images" before stacking? If you don't register they can't be stacked properly. Registration analyses the star quality and provides each image a point of reference so they can be aligned during the stacking process.

A mobile phone generally also has a noisy sensor, and too much noise in an image will affect the registration process too as the software won't be able to distinguish between genuine star signal and noisy pixels. Calibration frames can help to a degree, but for starters, I'd just try and stack the light frames to keep the process simple for you.

Double features in a stack usually means your images had some wind or unstable movement causing the camera to capture double.

[Abbas]

this one of the frames for example, could you tell me if anything is wrong with it

Darks_0011_20230418_023208.dng

[Abbas]

that's another frame as jpeg

[PeterCPC]

That is never going to stack. The star shapes are wrong and out of focus.

[michael8554]

Here's your jpeg image with a bit of stretch:

I can only see 5 stars in the image, they seem round enough.

I loaded it into DSS and it found 3 stars with star detection threshold set to 8%, FWHM = 4, score 19.53

And 15 stars at 7%, which I'd say will be mostly hot pixels, so not a good setting for stacking.

I took about 30 x 4minute exposures of The North American Nebula with a modded DSLR.

And those 2 hours of exposure needed heavy stretching to bring out the nebula.

You'll need to choose much much brighter targets.

Michael

[PeterCPC]

This is a blow up - stars are not round.

[Abbas]

Although in some frames at the beginning of the shooting session the stars were fairly round, and the frame I've sent was later at the end of the session, did I have to adjust the focus after a certain period of time?

[PeterCPC]

54 minutes ago, Abbas said:

Although in some frames at the beginning of the shooting session the stars were fairly round, and the frame I've sent was later at the end of the session, did I have to adjust the focus after a certain period of time?

Doubtful, temperature can affect focus but I can't see that being an issue at the moment.

[Elp]

In general, imaging through an eyepiece is not ideal due to the curvature of the eyepiece lens you'll get coma shaped stars away from the centre of view. You can get results, but if you intend on stacking you have to secure the camera in a way it won't move, like at all which is very very difficult. Using a wider (lower power) eyepiece like 30mm will give you a wider view and see more stars to register with. Check your tripod+mount also. If you move it around with your hand just rocking it side to side does it flex a lot (if you're looking through the scope at the same time at stars you'll see the effect magnified). A capable imaging system will hardly move, and if looking through the eyepiece will dampen down such movement in something like 1-2 seconds or less and be little affected by wind breezes.

I'd try and get your stars round at the moment, it doesn't look like you're at focus, and your scope collimation could be off.

 

[Abbas]

5 hours ago, Elp said:

In general, imaging through an eyepiece is not ideal due to the curvature of the eyepiece lens you'll get coma shaped stars away from the centre of view. You can get results, but if you intend on stacking you have to secure the camera in a way it won't move, like at all which is very very difficult. Using a wider (lower power) eyepiece like 30mm will give you a wider view and see more stars to register with. Check your tripod+mount also. If you move it around with your hand just rocking it side to side does it flex a lot (if you're looking through the scope at the same time at stars you'll see the effect magnified). A capable imaging system will hardly move, and if looking through the eyepiece will dampen down such movement in something like 1-2 seconds or less and be little affected by wind breezes.

I'd try and get your stars round at the moment, it doesn't look like you're at focus, and your scope collimation could be off.

 

Okay thank you all, I'll try adjusting my focus perfectly

+ About collimation, my scope is a refractor so I don't need collimation right?

[Elp]

Generally no.

[dph1nm]

Note that DSS requires a minimum of 8 stars in common between images for it to be able to stack. Don't think the example given meets that criteria.

NigelM