NGC 4565 - LRGB

Finally put together my RGB for this object. Once again the CA of the Tak doublet rears its ugly head on the blue stars. Its not so noticable in this image due to lack of bright field stars, but there nonetheless. In the future I might try putting a minus violet filter on the camers nosepiece when taking RGB data. critiques appreciated. Vince


FS-102
ST-2000XM
LRGB 120:60:60:60
RGB binned 2X2

Attached Image:

Very nice!

A note on the blue rims on your stars. Even images from the best corrected triplet APOs can have stars with blue rims. It isn't always CA (chromatic aberration). One mistake some imagers make is that they do not re-focus often enough. If your scope has a short focal length then the critical focus zone can be very small. A small drop in ambient temperature can easily take you out of the focus zone for your telescope. I use an AP 155EDF f/7 and it is color corrected to near perfection. However, if I don't re-focus before each filter change then I can get blue rims on my stars as well. Some imagers advocate re-focusing every 30-60 minutes depending on the drop in temp. I use a Robofocus and FocusMax to automate the process. Also, parafocal filters are not always as parafocal as they could be.

So, if you don't already, try re-focusing before each filter change and see if that reduces your blue rims.

Best,
Tom

Nice shot. I like the field galaxies scattered about.


Joe

Vince,
Really nice image. The color overall seems very good - I don't mind a little blue around the hot stars. (I've gotten quite used to seeing it with my equip).

You mention considering a minus violet - I have used a IR/UV cut with my RGB's - not exactly the same but I do see less FWHM on the blue with it. Also, I thought that some blue haloing came from atmospheric dispersion as well. If so, I guess nothing you do with optics would reduce FWHM beyond some limiting value.

Of course you could always shoot in poor seeing - its a great equalizer if you don't mind all your stars the size of small planetaries.

Warren is right, PS can be set up for effective blue halo reduction.

That's a very nice image Vince! 8)
Thanks for sharing!

CA on the TAK Doublets? First time I hear such thing...

Sweet image Vince!

thanks for all the comments everyone!

I'm a little late, but I wanted to add that this is a sweet image, Vince!

Eric