20mm Wide on Milkyway

astronobob (Bob) · #1 21-07-2020, 11:56 AM

Had beautiful clear, dry Bortle 2'ish skies '14th Jul' Rathdowney SEQld.
Canon 6D II, Star-Tracker, Sigma 20mm Art.
15 x 30sec, F2, ISO2500

1.3Mb - https://imgur.com/AwzmMzc

gregbradley · #2 21-07-2020, 12:42 PM

That's a terrific shot Bob.

Do you get much coma in the corners of the 20mm Art? The 28 Art gets good reviews but I would prefer 20mm as its a good wide focal length for this type of shot.

Greg.

astronobob (Bob) · #3 21-07-2020, 01:03 PM

Quote:

Originally Posted by gregbradley

That's a terrific shot Bob.

Do you get much coma in the corners of the 20mm Art? The 28 Art gets good reviews but I would prefer 20mm as its a good wide focal length for this type of shot.

Greg.

Thnx & Certainly do Greg, I always crop off some but here is pixel crop from the whole single frame, top left corner..
Hope gives an idea of corners I get - not too shabby all considering the width of view.
I do find these Art Lens's are much better at controlling coma and particularly color fringing than the Canons range, by a long shot actually, i will never buy another Canon lens for astro unless they correct the issues..
Rgrds

gregbradley · #4 21-07-2020, 03:48 PM

Quote:

Originally Posted by astronobob

Thnx & Certainly do Greg, I always crop off some but here is pixel crop from the whole single frame, top left corner..
Hope gives an idea of corners I get - not too shabby all considering the width of view.
I do find these Art Lens's are much better at controlling coma and particularly color fringing than the Canons range, by a long shot actually, i will never buy another Canon lens for astro unless they correct the issues..
Rgrds

Thanks Bob. Yes that is similar to my 14mm Art 1.8.

One trick is to compromise focus between the centre where these lenses are extremely sharp and the corners. You can get the corners almost round. Then you can apply a bit of distortion correction in Lightroom to further improve it.

Greg.