lack of fine detail, why?

[scitmon]

I'm currently processing my subs for M31 in photoshop (still learning) and I am a little underwealmed by the lack of detail when i really zoom into the image, compared to other people's efforts with the same/similar equipment.  Here is a work in progress example of my image: 

Equipment used: SW 80ED DS-Pro, 0.85 flattener, Canon 700d astromodded, all on a SW AZEQ6-GT, ungudied and dithered.  84 x 90 second lights, 30 flats and 50 bias.

I would like to understand where I have fallen short.  I suspect, looking at my stars, that the tracking fell short a bit?  I have a guide scope and camera incoming for next time. 

Perhaps something else?  Poor photoshop skills?

[Mr niall]

I see what you mean - very pretty though. It looks fractionally out of focus. Are your indivdual subs sharper?

[scitmon]

Yes I believe so.  The stars on this image heavily stretched, not corrected them yet.  I share my individual subs when I get home from work if people want to take a look at them.

[Mr niall]

Ah well I'm out of ideas then - maybe someone with some proper knowledge can advise! Looks 99% there though, best of luck sorting it.

[PeterCPC]

Looks out of focus to me too.

Peter

[DaveS]

Looks a touch out of focus to me too, plus I see some trailing. Did you use a Bahtinov Mask?

[scitmon]

Well I must confess I did use a Bahtinov mask, but it was the night before.  I didn't adjust focus in between sessions but I really should have redone it.  Lesson learned I guess.

[ultranova]

Its a combination of being out of focus and tracking

not being spot on, any one of those two will lead to a

un-sharp picture.

Maybe your focus drifted off during your session,

I have had pictures come out like yours, and its a pain

because you go to all the trouble of setting the equipment up

letting it run only to find out something's not quite right.

1/  always double / triple check your focus before the start

of a imaging run, and if your in for a long session check it half way through.

2/ Likewise, double check your aligned as best as possible,

and you know your limitations of the equipment you are working with.

after all clear nights, especially clear moonless nights are quite rare

in the uk  these days.

so its worth doing the extra mile at the start

Paul 

 

[Spikey]

I think you may have some subs that are soft for some reason. Passing cloud perhaps? Also to get depth you need longer subs. 90 seconds is a bit on the short side. Fine for the larger structure but will lose out on the finer stuff.

[wimvb]

9 hours ago, scitmon said:

Well I must confess I did use a Bahtinov mask, but it was the night before.  I didn't adjust focus in between sessions but I really should have redone it.  Lesson learned I guess.

Why not check the star shapes from "the night before" with those of this image? If focus has shifted, you should be able to see this by comparing subs/stacked images.

To improve this image, you can select just the best subs and stack these. This will give you a noisier image, but probably also sharper.

[scitmon]

Here is the image I took the night before:

seems to be better to me?  

I'll study the individual subs and see what I can do.

[wimvb]

Looks much better. Focus shift is the most likely cause of the blurring, then.