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pjphilli
06-08-2008, 11:34 AM
Hi
I image using DSI I or II cameras on a Meade 80mm f6 APO refractor.
I have done star tests using a high power eyepiece on the above scope and it shows no sign of bad collimation or chromatic abberration. However, both single and stacked images always show coloured background stars as per attached sample which is a composite of 30x1minute guided images of the Omega nebula in Sagittarius stacked, aligned both translate and rotate, combined, stretched in ImagesPlus. Any ideas what's wrong?
Cheers Peter

Blue Skies
06-08-2008, 08:05 PM
Violet, purple and green - nice! Perhaps this should be down in the imaging forum, though? The people who know might not check out your post here.

Merlin66
06-08-2008, 08:54 PM
From a comparison with the spectral colours given in CnebulaX software ( see attached screen dump), your camera certanly seems to be showing generally correct star colours. More sensitive in the yellow and the fainter red stars ( not to many in the field) are more white. The processing may have exaggerated the colours due to saturation.....

pjphilli
07-08-2008, 10:02 AM
Thanks Jacquie - you are right so I have reposted my thread in the imaging forum.
Thanks Merlin 66 - I am using a Hutech light pollution filter and I thought this may have been the cause but images remain much the same when the
filter is removed. Saturation could be a problem but a one minute image of the Omega is obviously underexposed with respect to the nebulosity which is why I employed the stacking. Single images are little different from the stacked image wrt star colouration. I will experiment with a range of short to longer images. I will also have to see what the imaging forum people have to say!
Cheers Peter