First Deep Sky imaging - are those dots really all stars?

[Barnjet]

I took some images of M31 last September on a dark night with reasonable seeing using the following set-up: 

Canon EOS-70D, Takumar 135mm prime lens, F3.5,  ISO 6400,  Exp 20sec mounted on a polar-aligned (visually) Vixen Polarie and Ravelli tripod. 

I took 14 x lights, 6 x darks, 22 x bias but no flats or dark flats ( I haven't figured out how to do that yet) in Large JPEG format.

I recently acquired Affinity Photo and using the Astronomy Stack feature,  and nothing else, I produced the attached image.    I'm quite pleased with it but I can't believe all those dots are stars, maybe they are? 

Please could the more experienced members advise how best I could improve the image.    

Thanks in advance

 

[CraigT82]

That's a really nice image, I'd be happy with that.  Yup all stars, there are a LOT of stars out there!

In terms of improvements, I'd say that you could probably get longer than 20 secs when using a Polarie and a 135mm lens... Concentrate on getting the PA as good as you possibly can you should be able to go for a couple of mins exposures at least. Also shoot in RAW format not jpeg.

[Astro Noodles]

It's a good image.

Maybe try a lower ISO, and go for more integration time as well.

If you processes this through image editing software you will probably be able to pull out a lot more detail from Andromeda.

[Barnjet]

1 hour ago, CraigT82 said:

That's a really nice image, I'd be happy with that.  Yup all stars, there are a LOT of stars out there!

In terms of improvements, I'd say that you could probably get longer than 20 secs when using a Polarie and a 135mm lens... Concentrate on getting the PA as good as you possibly can you should be able to go for a couple of mins exposures at least. Also shoot in RAW format not jpeg.

Thanks, polar alignment is a little tricky without Vixen’s polar scope, but I’ll certainly try, maybe use a spirit level to ensure the azimuth plane is level.  And use RAW format. 

[Barnjet]

31 minutes ago, Astro Noodles said:

It's a good image.

Maybe try a lower ISO, and go for more integration time as well.

If you processes this through image editing software you will probably be able to pull out a lot more detail from Andromeda.

Thanks, just to be sure does “integration time” means more lights and/or longer exposures?

Affinity says it also does image editing, but that is a process I have yet to understand.   I confess, I’m finding a lot of the image processing terminology a little baffling eg “stretching” “rasterising” etc   But,  I’ll get there in the end! 

[Astro Noodles]

24 minutes ago, Barnjet said:

Thanks, just to be sure does “integration time” means more lights and/or longer exposures?

Affinity says it also does image editing, but that is a process I have yet to understand.   I confess, I’m finding a lot of the image processing terminology a little baffling eg “stretching” “rasterising” etc   But,  I’ll get there in the end! 

More lights. 

Image processing is at least half of astrophotography, and probably more difficult than image capture. Stick with it and you will get there in the end. 🙂

Are you in the UK? If so, the biggest challenge is probably getting clear dark nights.

[Barnjet]

1 minute ago, Astro Noodles said:

Are you in the UK? If so, the biggest challenge is probably getting clear dark nights.

Yes in deepest, darkest Dorset, so autumn is a particularly good time to view Andromeda.  I’ll fill in some of my profile details

Thanks again. 

[Paul M]

That is a very pleasant image. Honest and understated. As stated already, there may well be more detail to be pulled of that but be careful not to spoil it!

[Barnjet]

3 hours ago, Paul M said:

That is a very pleasant image. Honest and understated.

Thank you Paul, that is very kind of you and hugely encouraging for me to try to improve.  This is a truly humbling hobby.  When I really consider this image, I can scarcely believe that the photons that ended up on the sensor of my camera left Andromeda about 2.2 million years ago! 

[Lee_P]

Cracking shot, you should be happy with that as an initial effort! As others have suggested, a longer total integration time and a bit more experience with processing, and I reckon you'll have something to hang on your wall 😁

[Swoop1]

I'd be well chuffed if I produced that! Better than any of my efforts so far.

[alacant]

20 hours ago, Barnjet said:

improve the image

Hi

Lovely image.

1- Use ISO800

2. The Takumar 135 (and other Takumar lenses) focus the green and blue, leaving the red blurry. Focus on a brightish white star as tight a HFR as possible. Now move focus away from infinity until the red halo just disappears.

3. Unless you have the f2.5, it doesn't look like you used f3.5; there are diaphragm spikes. Try f5.6.

4. eos70D? Lose the dark frames.

5. Set the camera to RAW.

6. Take at least a thousand frames.

Cheers and HTH

 

Edited August 6, 2021 by alacant

[Barnjet]

13 hours ago, Lee_P said:

Cracking shot, you should be happy with that as an initial effort! As others have suggested, a longer total integration time and a bit more experience with processing, and I reckon you'll have something to hang on your wall 😁

Thanks Lee, something to aim for!

[Barnjet]

13 hours ago, Swoop1 said:

I'd be well chuffed if I produced that! Better than any of my efforts so far.

Thanks for the encouragement! 

[CraigT82]

13 hours ago, Lee_P said:

Cracking shot, you should be happy with that as an initial effort! As others have suggested, a longer total integration time and a bit more experience with processing, and I reckon you'll have something to hang on your wall 😁

I must say your website is brilliant (on my laptop and only just noticed the link in your sig - I usually use a mobile device). Love the way youv'e presented single subs alongside the finished images, and the sliders to compare. We may have even briefly met as I went to the planetarium at we the curious a lot (when we could)

[Barnjet]

9 minutes ago, alacant said:

The Takumar 135 (and other Takumar lenses) focus the green and blue, leaving the red blurry. Focus on a brightish white star as tight a HFR as possible. Now move focus away from infinity until the red halo just disappears.

Excuse my ignorance, but what is "HFR" ?

 

11 minutes ago, alacant said:

Unless you have the f2.5, it doesn't look like you used f3.5; there are diaphragm spikes. Try f5.6.

Yes - it's the f3.5 lens, so changing to f5.6 will remove the diffraction spikes? 

 

13 minutes ago, alacant said:

eos70D? Lose the dark frames.

Ok - that will shorten the image capture period 😎

 

14 minutes ago, alacant said:

Take at least a thousand frames.

Wow!  If I try increasing the exposure to 60sec for each light, then I need to spend 16.6 hours collecting light from M31  😲  I might work up to that one! 

 

19 minutes ago, alacant said:

Lovely image.

Thanks - I can't wait to try again using the advice I've received from this very helpful and friendly forum 😃

[Lee_P]

5 minutes ago, CraigT82 said:

I must say your website is brilliant (on my laptop and only just noticed the link in your sig - I usually use a mobile device). Love the way youv'e presented single subs alongside the finished images, and the sliders to compare. We may have even briefly met as I went to the planetarium at we the curious a lot (when we could)

Thanks Craig, that's very kind. The website is new and I'm always happy if people find it useful  More content on the way too!

If you ever went to any of the Planetarium Nights shows for adults then we probably did meet, as I presented a lot of those! Feels like a long time ago. I'd sometimes make 1x1 versions of my astrophotos and just blast them up onto the dome -- seeing your images 12-metres across in 4k resolution is a lot of fun 😂

[Steve143]

45 minutes ago, alacant said:

4. eos70D? Lose the dark frames.

Why lose the dark frames with the 70D? I'm very new to astrophotography and have just purchased a 70D and still experimenting with ISO and exposure times. I've also tried taking light frames only versus light frames and a full set of calibration frames, so any advice using this camera would be really helpful. Thanks!  

[alacant]

1 hour ago, Barnjet said:

but what is "HFR" ?

An acronym for a number we use in astrophotography. It gives an idea of if you're in focus.

 

1 hour ago, Barnjet said:

changing to f5.6 will remove the diffraction spikes?

No. To lose the spikes, either use the lens at f3.5, or if you want to try f5.6 (recommended) without the spikes, stop the lens aperture by using a circular cardboard or plastic cutout of around 25mm diameter

135 / 25 = 5.4

Close enough.

HTH

Edited August 6, 2021 by alacant