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Hi! I've recently acquired a new Astromodified Canon rebel XT and I've tried to take pictures of nebulas using it but I've noticed that there are these weird black artifacts that keep appearing in my images. Would like to know if anyone has experienced this before? Or are these dirt/dust specs on the camera, filter, and telescope glass? I've attached some of my edited and raw pictures for your reference. The black artifacts can already be seen in the raw image of the horsehead nebula and after stacking I think it got amplified. Anyway, advance thanks and I hope everyone's doing well.
I moved from color (Canon) DSLR camera's to more advanced ZWO black and white camera's with color filters. Now I have to handle gain and offset instead of ISO. In theory I think I understand very well what it's about, and took notice of the literature. In practice at the telescope I have to rely on trial and error with test exposures. Can someone point a (reference to a) cookbook-like procedure to me, which lead to the optimal setting of gain and offset?
Johan, Netherlands. [C14/Hyperstar, with a ZWO-183, and with a lot of light pollution.]
I am wondering if anyone has a suggestion that might help me
My imaging set up is an RC reflector with an FLI proline 16803 camera and 50mm Astrodon filters (LRGB + 5nm narrow band)
I have had a string of issues...everything from my mount had mechanical problems to my telescope had issues with the mirror cell to some family distractions...but at long last I seem to have everything working with the exception of the Astrodon Ha filter.
Attached are representative 30minute subframes of the horse head and Pacman nebulae in Ha, SII, and OIII. I get similar results with different objects although for bright, broad spectrum targets like M42, I will get data from the Ha filter (much as the stars shine thru on the HH and Pacman) although even that data does not comport with other imager’s Ha images of those objects. The LRGB performance appears to be normal. My hypothesis is that this Ha filter is defective, perhaps not centered on 656.3nm
I have contacted Astrodon and exchanged a couple of emails with Cary Chleborad seeking some help. At first he claimed there was no issue because with enough manipulation some data could be extracted from the Ha. Later, when confronted with the other narrowband frames and the obvious difference to the Ha, at first he ghosted me, but when I said I would ask other imagers for help, he responded with a new position stating that because of the way the filters are made and their robust quality processes, it is impossible for the filter to be defective and therefore something else must be at issue. He does not offer a suggestion of what might be the problem, nor is he interested in having me send the filter back for evaluation. Frankly, I’m more than disappointed given the premium I paid for Astrodon filters
All that aside, and taking Cary’s position at face value, does anyone have an idea of what might cause this behavior other than the filter? In a perfect world, does anyone live in the Austin, Texas area who would be willing to try my filter one night and see what they get with their equipment?
The attached link is to the raw, uncalibrated files right off the camera. I think a simple blink process in PixInsight will show what I’m talking about.
I’m a little at my wits end, please help!
I'm just getting started with compiling a collection of accessories to enhance my viewing. I want to add to the collection slowly, so i get a chance to learn from each new thing and use that experience to better inform the next purchase.
With that in mind, i was wondering if I'd be better served getting filters earlier or later in the process?
By filters I'm sure i don't really know what I'm talking about but i see on FLO a narrowband UHC filter (unbranded) and a celestron "CLS" filter - City Light Something, or essentially a light pollution filter. Both around forty quid, which is my budget. Both sound useful for me, I'm in a red zone (urban/ suburban). I'm interested in seeing more nebula - improving the Orion nebula, i saw someone said a filter helped them see the veil nebula with similar equipment to me in similar conditions.
So... any thoughts or advice? : )
i have an f/8 skywatcher dobsonian 6", with the stock 10 and 25mm eyepieces, and an 18mm BST StarGuider coming for my birthday... as well as an astro essentials moon filter and an astro essentials 2x barlow.