First DSO NGC2903 and a Ha question
Apr 11, 2021 13:03:40 #
Hi folks,
This is NGC2903, my first attempt at LHaRGB, however there is no Ha in the finished shot which brings me to the question. The first photo is the Ha with simple stretching and I consider it unuseable. I believe there is dirt or dust bunnies on the remote telescope and would like you to confirm my diagnosis or come up with a viable alternative. The 2nd photo is the LRGB version with some actions added most prolific of which is Ha false color but toned down. Let me know what you think.
Before you ask, I have no idea as to telescope or camera other than CCD Monochrome. This is a remote scope at one of our local astronomy clubs. Second, for those not into star points... tough noogies.
All LRGB photos also had the smudging at top and left along with a couple of rain drop smears?? 25% from bottom and centered. I did my best to eliminate them. This whole endeavor was fun even with the nasties. Just noticed the jpg Ha has very little detail so also including the tif version... if I can.
This is NGC2903, my first attempt at LHaRGB, however there is no Ha in the finished shot which brings me to the question. The first photo is the Ha with simple stretching and I consider it unuseable. I believe there is dirt or dust bunnies on the remote telescope and would like you to confirm my diagnosis or come up with a viable alternative. The 2nd photo is the LRGB version with some actions added most prolific of which is Ha false color but toned down. Let me know what you think.
Before you ask, I have no idea as to telescope or camera other than CCD Monochrome. This is a remote scope at one of our local astronomy clubs. Second, for those not into star points... tough noogies.
All LRGB photos also had the smudging at top and left along with a couple of rain drop smears?? 25% from bottom and centered. I did my best to eliminate them. This whole endeavor was fun even with the nasties. Just noticed the jpg Ha has very little detail so also including the tif version... if I can.
Apr 12, 2021 11:13:40 #
My first thought was focus, but the stars are all sharp.
There are several Ha filters, so that might have some bearing on your results.
I use an Ha7nm filter. And my newest filter, (Optolong Extreme) has an Ha band in it.
But all my tries with Ha yield a red image. Or enhance the red spectrum. (But only with the two filters).
I use a color camera, and don't do Mono camera imaging. I think I'm too lazy for mono.
There are several Ha filters, so that might have some bearing on your results.
I use an Ha7nm filter. And my newest filter, (Optolong Extreme) has an Ha band in it.
But all my tries with Ha yield a red image. Or enhance the red spectrum. (But only with the two filters).
I use a color camera, and don't do Mono camera imaging. I think I'm too lazy for mono.
Apr 12, 2021 12:10:59 #
Apr 12, 2021 15:32:05 #
Paul Diamond
Loc: Atlanta, GA, USA
I think it's great to be using a club asset on a remote sharing basis. - Suggestion - To make the learning experience more complete, suggest you get the statistics of what is being used. focal length, aperture, digital camera model number, etc.
Apr 12, 2021 18:49:14 #
I have not done what you have, but I keep reading about parafocal filters as compared to not. Looks to me to be a focusing problem, maybe due to the Ha filter. Does the scope refocus between filters, can you make it do so? A loose filter might cause all kinds of problems?
Apr 13, 2021 05:26:20 #
Hi,
What is the band width of the Ha filter...3 nm, 7 nm, 12 nm, other? What were the exposure lengths for the Ha data? It looks to me like you don't have long enough exposure for the Ha data. As the band width of the Ha filter gets smaller, it lets less and less light in. Often 10 or 15 min individual exposures are required to capture sufficient Ha depending on the target. It also looks like you mentioned that the filter is really messy. Just something to ponder. Hope it's helpful.
Jay
What is the band width of the Ha filter...3 nm, 7 nm, 12 nm, other? What were the exposure lengths for the Ha data? It looks to me like you don't have long enough exposure for the Ha data. As the band width of the Ha filter gets smaller, it lets less and less light in. Often 10 or 15 min individual exposures are required to capture sufficient Ha depending on the target. It also looks like you mentioned that the filter is really messy. Just something to ponder. Hope it's helpful.
Jay
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