Wide M57 with satellite, also M27 and M13

[Ludd]

Having decided that the skied were not going to stay clear for long enough for it to be worth setting up the GPDX, I took a few shots with my Canon 600D on an iOptron skytracker.  Here's a minute's exposure at ISO 400 through an old 200mm pentax lens stopped down to f5.6.  I was using an Astronomik CLS clip filter (I live in London) and so there is a funny colour cast - but is the red on the brighter stars chromatic aberration in the lens?)

widem57 by PaulRide, on Flickr

widem27 by PaulRide, on Flickr

widem13 by PaulRide, on Flickr

[jambouk]

How zoomed in is that image? It looks too solitary red for chromatic aberration; hot pixels of some sort?

Jd

[Ludd]

How zoomed in is that image? It looks too solitary red for chromatic aberration; hot pixels of some sort?

Jd

It's not massively cropped, and the red shows up very strongly on pretty much all the stars - definitely not just hot pixels.

[jambouk]

Could well be CA then if it is on every star. That would seen like the most obvious cause then. Does it appear if you use other lenses / at prime focus on a scope?

Have you adjusted the white balance to compensate for the CLS filter?

Jd

[wxsatuser]

I have checked the stars in your M13 image and the colour is bang on.

All the red stars are actually orange/red stars so your colour is good.

Some of the blue and white stars in the M57 image have red halos.

[jambouk]

I can't see any of the images

[Adamar98]

Nice images! I get the red halos in my stars when I'm slightly out of focus. Red halos one side of focus and blue halos the other side of focus.

HTH

Adam