Feedback Please

[Simon Pepper]

Hi all,

I was after some feedback on my image of Andromeda please , but please dont be too harsh. This was my first ever imaging session which I think looks ok, but I have some questions around it to try and improve next time. Firstly the obvious its not centred and as a result I have missed the orbiting smaller galaxies. I had some issues getting it in the middle and eventually gave up as time was ticking. Next time I will get this right!

I have attached the stack out of DSS and can see the top and the bottom of the image is darker because its shifted. I noticed while imaging it was slowly moving up. Is this a result of dithering or is this a result of my polar alignment not being perfect? Is my image in focus? This probably seems like a ridiculous question, but I feel I need to ask to me it does look good? Is it noisy could my calibration frames been better? My Photoshop edit appears a little out but I think this is because you need a degree in Photoshop which I dont have and I have really winged this part. Also the image is now in .jpg which has decreased its size. The Photoshop final I feel could have been much better but as I have not used it before I really struggled it looks quite green especially to the bottom left. 

It was 40 minutes of exposures in total. My ISO was 800 at 90 seconds subs. I used a canon 800d with skyguider pro and redcat. I used 21 darks, 25 flats, 31 bias. 

Any feedback or tips to try next time will be welcome.

Thanks 

Simon 

[CloudMagnet]

I would say for a first imaging session it is fantastic, far better than my first. I would say the focus looks a little soft though but easy fixed next time. You can try adding a little sharpen and that should make a difference.

In terms of the drift, dithering works by moving the image a few pixels in random directions rather than a constant drift one way, so I would put this down to polar alignment/mount tracking error. If you were dithering, you would also be guiding which should eliminate any drift so I cant imagine that being the case.

With a DSLR, noise will be an issue with long exposures and warm summer nights as well, not much you can do but add exposure time to average it out. 40 mins isnt a long time in astrophotography, images are exposed in the order of hours rather than minutes so I think this is a good result to build on

[Simon Pepper]

16 hours ago, CloudMagnet said:

I would say for a first imaging session it is fantastic, far better than my first. I would say the focus looks a little soft though but easy fixed next time. You can try adding a little sharpen and that should make a difference.

In terms of the drift, dithering works by moving the image a few pixels in random directions rather than a constant drift one way, so I would put this down to polar alignment/mount tracking error. If you were dithering, you would also be guiding which should eliminate any drift so I cant imagine that being the case.

With a DSLR, noise will be an issue with long exposures and warm summer nights as well, not much you can do but add exposure time to average it out. 40 mins isnt a long time in astrophotography, images are exposed in the order of hours rather than minutes so I think this is a good result to build on

Thank you I will be sure to get that focus a little better. Thats it then guiding and more exposure time is the way forward  Heading over to FLO now for some extra gear!!! 

[Aramcheck]

I've also initially had trouble centering / locating objects. I found Astro Photography Tool (APT) to be a great help, as I'm no longer reliant on the camera live view. APT also has the advantage of being able to plate solve images & iteratively refine the mount position until the object is centered (or positioned wherever you want  it to be)...

For focusing, a Bahtinov mask (either made or bought) will help get precise focus, & here APT's Bahtinov Aid tool is useful too.

If you find that you still can't get good polar alignment (or that it eats into imaging time too much), then have a look at something like the iPolar...

Cheers
Ivor

PS: You're stars look nice & round which is a good start!

[Simon Pepper]

3 hours ago, Aramcheck said:

I've also initially had trouble centering / locating objects. I found Astro Photography Tool (APT) to be a great help, as I'm no longer reliant on the camera live view. APT also has the advantage of being able to plate solve images & iteratively refine the mount position until the object is centered (or positioned wherever you want  it to be)...

For focusing, a Bahtinov mask (either made or bought) will help get precise focus, & here APT's Bahtinov Aid tool is useful too.

If you find that you still can't get good polar alignment (or that it eats into imaging time too much), then have a look at something like the iPolar...

Cheers
Ivor

PS: You're stars look nice & round which is a good start!

Thanks Ivor