Bloated stars after processing

[iapa]

I’ve restacked some data from about 2017 of Bode’s Nebulae.

Stacked in DSS,

M81-82 DSS stackno calib.TIF

and processed using PhotoShop for iPad.

M81-82 DSS stackno calib.TIF

1883441A-3487-48FA-A84D-21CFB09EC34B.tiff

41A33D0E-2D89-4D05-81F5-68A89DE98103.tiff

Where have I gone wrong?

 

 

 

 

 

Edited April 29, 2021 by iapa

[Chefgage]

I do not understand the question. What is supposed to have gone wrong??

[iapa]

Stars are not round despite auto focus  every few frames and >2C temp changes

bloating

[teoria_del_big_bang]

Bloated - yes to an extent, but I think they are pretty round.

I am probably not knowledgeable enough to say what , if anything, is wrong with this image.
But I do not think there is too much wrong with it.

Stars are pretty round, maybe in corners a little elongated but not by much.
I do not think they are too far out of focus but you would have to look through all the frames rather than the final stacked image as if you are auto focusing at regular intervals then maybe some are pinpoint focus and others not so.
Not sure what software you are using, or were using in 2017 but as I have found out lately auto focus can be tricky to get just right.
Also again would need to see some raw images as bloating will probably be from the processing and nothing to do with the acquisition.

What are the individual frame exposure details ?

As I say I probably am not advanced enough to help anyway but I think more details of how the images were acquired and the software used to process would help.

But, and it is a big but, from a novice perspective, I would say that maybe the galaxies need more data (more frames or longer exposures, or both) so that you do not have to be so aggressive in the processing as unless you do something like removing the stars with Starnet (or using star masks)  partway through the processing so you can further stretch the galaxies without bloating the stars and creating the magenta halos, and then re-introduce the stars this effect on the stars will happen.

Also depending on the processing software you are using there are ways to remove magenta halos (or at least reduce them) .

Steve

Edited May 3, 2021 by teoria_del_big_bang

[Cornelius Varley]

Title amended.

[alacant]

On 29/04/2021 at 21:20, iapa said:

have I gone wrong?

Hi

Nice image:)

There's a large rotation error so losing a lot of the image around the edge and either flat frames have not been applied or they have not been calibrated correctly. Otherwise it looks OK to me. I had a go at the stars:

 

 

 

 

Edited May 3, 2021 by alacant

[teoria_del_big_bang]

@alacant Wow,that image does have a fair bit of detail in the galaxies and nice looking stars, so I was wrong it was not a lack of data in the subs but all in the processing. 🙂 

Steve

[iapa]

This was from Modded 600D, 50mm f.14 lens

Mount would have been Celestron AVX.

Over at least 3 nights I expect.

110 x 120s @ ISO 800

38 x 60s @ ISO 800

22 x 30s @ ISO 800

Stacking WAS DSS using a group for each exposure setting.

Edited May 3, 2021 by iapa

[alacant]

10 minutes ago, teoria_del_big_bang said:

not a lack of data

Hi

Agreed. The data is good enough to push more than the OP's original. Nice:)

 

[teoria_del_big_bang]

15 minutes ago, iapa said:

This was from Modded 600D, 50mm f.14 lens

Mount would have been Celestron AVX.

Over at least 3 nights I expect.

110 x 120s @ ISO 800

38 x 60s @ ISO 800

22 x 30s @ ISO 800

Yes well I think @alacant has demonstrated the data is good data and capable of bringing more out of the galaxies without bloating the stars.
Which is why I was sort of saying take my thoughts with a pinch of salt as this is why peoples experience in processing is so important and like many I am still learning all this 🙂 

Steve

Edited May 3, 2021 by teoria_del_big_bang

[alacant]

2 hours ago, iapa said:

600D, 50mm f.14 lens

Wow, really?

[scotty38]

Unless it’s a typo that’s mightily impressive for a 50mm lens

[iapa]

1 hour ago, scotty38 said:

Unless it’s a typo that’s mightily impressive for a 50mm lens

Canon “nifty fifty”, It’s a prime focus, f1.4, 50mm.

[scotty38]

Just now, iapa said:

Canon “nifty fifty”, It’s a prime focus, f1.4, 50mm.

Yep I know what it is that’s why I’m amazed, must be cropped somewhat and to retain that detail is great.

[iapa]

OK

This is one of the uncropped, 30s exposure at ISO800, RAW (CR2) image from Canon 600D, f1.4, 50mm lens.

I opened this in Lightroom on iPad.

[alacant]

Here is my version of the same area of sky with a 135mm lens on an eos700d, which has the same sensor...

Confused!

 

[Seelive]

And here's a full frame Canon 200D image of the pair with a 400 mm lens!

[scotty38]

Light polluted but GT81 @ 382mm and 294mc with m4/3 

 

Edited May 3, 2021 by scotty38

[iapa]

Given all the commentary, I’ve been looking at this all ways.

Last was Astronometry which shows

I then calculated the FoV for 600D with a 50mm fl f1.4

Which gives pixel scaled 17.74 and size of 25.6 and 17.1

So, the meta data in the images is incorrect.

I have several OTAs and I think the closest would be the StarWatcher Equinox ED80, 500mm fl, f6.3.

So,

1st apologies for unintentional misrepresentation

2nd I now have to go through all these images and change the meta-data.

 

 

[scotty38]

Ha, you saved us all from rushing out to buy that lens though lol