Isn't CA Pretty . Yes?

[JRWASTRO]

Periodically one does complain about chromatic aberration but sometimes it can look quite pretty.

Here is a picture, 15s exposure taken on an old(er)  Canon 5D using an 85mm F1.2 lens, where the CA looks quite pretty. I've given up getting "stressed out" when using this lens for astronomical stuff.

Jeremy

[JRWASTRO]

Just a quick note:

The last picture was taken with the camera on a standard photographic tripod.

JRW.

[wxsatuser]

The red is not so obvious, on my laptop screen, in this extrafocal image, it is there but I had to look hard.

The blue halos are not to distracting, others may find them objectionable.

On the other hand the coma to me is more objectionable as the eye is drawn to it.

[michael.h.f.wilkinson]

Nice shot indeed. It also shows the Coal Sack nicely. I am not sure CA is the biggest problem. What you might also be seeing is spherical aberration  (even my Zeiss Planar F/1.4 85mm shows that to some degree at full aperture). This might be  worse for blue than for red, of course, as the degree of the aberration can be wavelength dependent. Coma can also be seen in the corners

[ronin]

Best bit I like is the comment:- I've given up getting "stressed out".

It really isn't worth it no matter what it is involved, I think more should adopt it.

[JRWASTRO]

Thank you for the taking the time to view this image.

1. Yes Ronin sometimes its like an audiophile listening to some fine music. All he hears is the distortion!! This lens produces excellent results for terrestrial stuff.

2. Hyper Giant. Photographing star fields does take excellent and well corrected optics and as for other distortions? Well , in my case, unless it is obvious and "in your face" I have not got the experience to recognise them. But i do listen to comments and learn from them. Yes it is a nice pic showing good detail. The best part is that it did not take much effort to obtain it.

3. Thanks for taking the time Mike. "Extra focal" image . i'll work that one out. Some chaps have the experience to tell which is the side of the focus error And I certainly do not! But I do appreciate what you are saying. There are times when I find CA to be annoying but here is looks alright to me. About recognising other distortions , well unless they are seriously bad I do not see them ... Ignorance is bliss.

Thank you again chaps,

Clear skies,

Jeremy.

[PeterCPC]

It's hard not to get stressed out here - due to the weather of course.

Peter

[JRWASTRO]

It's hard not to get stressed out here - due to the weather of course.

Peter

It gets pretty frustrating here too Peter. The only place that produces continuously good skies is Alice Springs ( I lived and worked there). It hardly rains there and the humidity is always very low ... Cars do not rust out there.

Jeremy.

[wxsatuser]

Thank you for the taking the time to view this image.

3. Thanks for taking the time Mike. "Extra focal" image . i'll work that one out. Some chaps have the experience to tell which is the side of the focus error And I certainly do not! But I do appreciate what you are saying. There are times when I find CA to be annoying but here is looks alright to me. About recognising other distortions , well unless they are seriously bad I do not see them ... Ignorance is bliss.

Thank you again chaps,

Clear skies,

Jeremy.

An intrafocal image would have red a fringe and centre tinged with blue.

The extrafocal image has a fringe of blue/violet and a centre tinged with red.

[JRWASTRO]

An intrafocal image would have red a fringe and centre tinged with blue.

The extrafocal image has a fringe of blue/violet and a centre tinged with red.

Thank you Mic for the breif explanation Now I've learned something.

Jeremy.

[lensman57]

This is not at all bad. One thing you can do is to stop down the lens but rather than using the aperture ring which itroduces spikes you can cut out a mask and use it in front of the lens, it is almost as effective as stopping down but will not introduce spikes. You may also wish to use Noel Carboni's action in PS to further reduce the halos.

A.G

[JRWASTRO]

This is not at all bad. One thing you can do is to stop down the lens but rather than using the aperture ring which itroduces spikes you can cut out a mask and use it in front of the lens, it is almost as effective as stopping down but will not introduce spikes. You may also wish to use Noel Carboni's action in PS to further reduce the halos.

A.G

Thank you A.G .

I will definitely try stopping down when the weather improves. In the mean time I'll make a mask too and try this out too. About getting rid of the halos: I'm of the old school where I would do every thing so that the halos were not there in the first place or just live with them!!

I'll post the results here. Winter here is producing some terrible nights.

Jeremy.