Here's another near infrared image, this time of M17, using the Astrodon near infrared filters. The nebula still looks the same although significantly reduced and you get a lot of obscured stars now being visible. I may do a mouse over at some stage. I hasten to add that these images are interesting curiosities without being all that scientifically accurate.
To anyone interested I did a reprocess of this. The original version was cropped to remove the bright double star on the right. This time I decided to leave it in. I also made a number of other changes which hopefully improve the image.
Steve. 850nm seems to be OK. I read that humidity is a problem and longer wavelengths do better. I've had my eye on a ~1000nm filter to pair up with a full spectrum Canon but on second thoughts perhaps 850 is adequate.
NIR has been in the pipeline for a while. And possible now that auto-guiding is up and running.
Steve. 850nm seems to be OK. I read that humidity is a problem and longer wavelengths do better. I've had my eye on a ~1000nm filter to pair up with a full spectrum Canon but on second thoughts perhaps 850 is adequate.
NIR has been in the pipeline for a while. And possible now that auto-guiding is up and running.
The limiting factor is the IR response of the CCD and you are correct - you are still getting about 30% for the 6303 at 850nm but at 1000nm that drops to 5% and goes to zero at 1100nm.
Very interesting image Steve. Definitely there are more stars visible in comparison to traditional narrowband image of this nebula. This might be also due to a larger than average amateur's aperture.
The original image looks good Steve plenty of star colour
Martin
Thanks Martin. Not sure what you mean by the original image.
Quote:
Originally Posted by Slawomir
Very interesting image Steve. Definitely there are more stars visible in comparison to traditional narrowband image of this nebula. This might be also due to a larger than average amateur's aperture.
Thanks Slawomir. Of course any LRGB image is always going to show more stars than NB. Judging by comparison with other IR images I think you are seeing IR stars here.
Yeah, different Steve, definitely looks like some different shaped gaseous features in there compared to normal and more stars too. The stars do looks a little crunchy and damaged though, is that an artefact of some star shrinking/processing or from the filters?
HI Steve
The image with the two bright stars you got more star colour
Martin
I must be having a bad day. When I first posted this image I cropped out the two bright stars at the right but decided to include them for the new version. On inspection I frankly don't see a lot of difference in the star colour between the two versions.
Yeah, different Steve, definitely looks like some different shaped gaseous features in there compared to normal and more stars too. The stars do looks a little crunchy and damaged though, is that an artefact of some star shrinking/processing or from the filters?
Mike
Yes - good call Mike. I did use star shrink and probably overdid it. The 6303 is a blooming CCD too and some of the brighter stars were a bit damaged by the deblooming process. I'll have another look to see if I can improve matters.
Yes - good call Mike. I did use star shrink and probably overdid it. The 6303 is a blooming CCD too and some of the brighter stars were a bit damaged by the deblooming process. I'll have another look to see if I can improve matters.
Thought so ...star shrink almost never looks any good to me, often worse than Decon, I can nearly always see when it has been used
...star shrink almost never looks any good to me, often worse than Decon, I can nearly always see when it has been used 
