Issue with concentric rings on E-M1 Mark II (edited title)

Started Mar 19, 2017 | Discussions thread
OutsideTheMatrix Senior Member • Posts: 4,936
Re: Going slightly off topic . . .

Astrotripper wrote:

Messier Object wrote:

Regarding the purple fringing in your original Orion image, which is obvious on the belt stars and Rigel . . .

Yeah, this was just a quick conversion with darktable, which just does not handle purple fringing well and makes it more noticeable than it normally is.

if it's real CA then you ought to be able to bring the purple light to a sharp focus. Have you tried doing a magnified view Manual Focus to eliminate the purple fringing. This would of course put the other wavelengths out of focus and bloat the star images, so it's not a solution.

Yes, that is what I have been doing when shooting stars since I got E-M10 and noticed this behaviour with Oly 45mm. There is usually some "sweet spot" where by slightly "misfocusing" I can minimize it to some degree without affecting other stars much. Usually works best by stopping the lens ever so slightly.

The problem with the Leica 12mm is that finding this sweet spot is much more tricky, as changing focus also impacts the way coma affects shape of stars near the edges.

Do you need to focus before or after 'infinity' to bring purple into focus ?

There are two problems. One is ordinary purple fringing that affects most lenses on most systems. And then there's this . And here's an update on the results of star testing 2A filter. Unfortunately, had not had the chance to do that in good conditions. It's always thin veil of clouds and severe light pollution. Now that I have E-M1.2, I will check if it behaves any differently than my E-M10. I will post an update to that other thread once I get around to that later this week.

Does the fringing go away when you attach the camera to a telescope that does not have fringing (like a reflector or compound scope).

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