Sorry looked too close. Dust donut found top left of frame. Seriously though, you'd be hard pushed to discover uneven field illumination in this image due to the globular. Looks like a slight gradient running from right to left. Right being the darkest point. The background to the left of the globular has a minor red tint to it. Why the rush to publish this image without taking flats Peter?
Well Jase, in your own words "hard pushed" and in my case "being forcefully led"
Seriously though, I wouldnt have noticed as I am no expert.
You didn't read my full statement - "hard pushed to discover uneven field illumination in this image due to the globular". This is technically accurate as vignetting, should it be present has the potential to be masked by the globular structure.
I'm no expert either, but I do know a thing or two. So here is a tip for you (et al). A method to validate data quality is to use the PS equalise function. It is a very good tool to check for background colour gradients. I've have attached a result of the output below. Clearly seen is the donut top left and the red shift/gradient from left to right (as per my comments).
My apologies Peter for making an example out of this image, however it serves as a good educational exhibit.
Thanks for the lesson Jase.
I guess I just take the pictures at face value without using software to highlight any flaws.
ps I did read your full statement, I just didnt type it out
Thanks for the comments...and Jase, rest assured I will do some flats! ...lack of time was the main reason, (I only use sky flats with the RC) but I'll do them weather permitting, when I get back from OS.
that is some image, man, what I would do for that type of imaging, and experience.
Such rich colour.
