Thursday, May 26, 2011
Wednesday, May 25, 2011
As I posted before, it does indeed look like proper calibration frames subtract the artifact right out of the image. I guess technically nothing has to be done about the glass stain. Cleaning it off is probably a good idea though.
With all of my work travel lately and other household obligations, I have been giving up night after night of clear skies for sleep. It's a sign that maybe now is a good time to switch gears. I had what I feel was a really good DSO imaging run over the last year. I cannot sustain those late nights at the moment to properly image DSOs any more. Not after I got a taste of what putting several nights of camera time into a single image can actually do. So, I'm putting the camera up for sale. I'm also going to sell the Vixen OTA and accessories. I bought it purely for imaging, and specifically to match up to the QHY-9.
I haven't fully boiled down what I want to do next but I have a really good idea. There are lots of AP imaging specialties that don't require sleepless nights. Planetary, Solar, Widefield, etc etc... None of these require heavy rigs, nor intense setup time, and in many cases, the gear is small enough to throw on an airplane with me. More to come on this one.
Sunday, May 15, 2011
If you fully expand the image you can see it much better. There's another, more faint artifact next to it. So I thought this was a hair, or something else that managed to find its way onto the IR window. Curious since I use my Vixen ED80SF for nothing else but imaging and the QHY-9 is almost constantly attached. It was showing up in my Light frames and Flats. So I took the camera off and inspected it closely, expecting to have to clean the glass. It wasn't on the IR glass, it appeared to be under it. So I removed the IR window to look closer and found it to be actually on the sensor itself, inside of the CCD chamber. What it looks like to me is some sort of epoxy or sealant boiled onto the sensor and hardended. It has the appearance of dried, clear glue. Getting a picture of this was difficult and it barely shows up with my digicam. I can see it plain as day though. Here's a couple attempted images of it. I outlined the area on the second shot.
So, for now, I can crop about 10-15% of each frame out and continue to use it as is, or, I need a new camera. This stinks since I was just ramping up for some Rho Ophiuchi imaging, and as any astrophotographer with experience knows, this area is huge. It was already going to take me building a 4 panel mosaic to get it all in there with the QHY-9 and Vixen @480mm. By losing the lower end of my frames, the mosaic tolerances just became more stringent. I've made a number of imaging attempts since discovering the "smudge" on the chip. It doesn't seem to be progressing or moving at all, so I suppose I can continue to operate this camera in a stable fashion, it just stinks to buy a big chip CCD like this for the purpose of having that big of a chip, and having to lose more than 10-15% of it.
Saturday, May 14, 2011
Friday, May 13, 2011
Sagittarius and Polar Rotation video clips
Here are a few of the single 60 second subs showing a few of the aircraft that made it through my FOV that night.. I think I counted over 50 when I screened the subs. The uploader compressed these quite a bit, I can see the jpg artifacts showing up so ignore the crunchy, haloed stars...
Tuesday, May 10, 2011
Another segment of a Milky Way Mosaic I'm working on. It extends from Sagittarius, through Ophiuchus, Serpens, and part Scorpius.
Two Panels, shot two seperate nights. 75 x 120 sec
Canon T1i ISO 800, 18-55 @ F/4.5
CGEM Mount / QHY-5 autoguider
Stacked in Nebulosity
Post processing by Sal Grasso, who's working to help me resolve a color cast issue between other panels to finish the mosaic.
Sunday, May 8, 2011
Reference to what I'm about to discuss can be found in these links:
Flats discussion 1
Flats discussion 2
Why this works, I don't quite understand fully yet, but here it goes. I put a grey t-shirt over the objective. Check out the results in this sample flat, and a quick image that I tested the flats against:
Friday, May 6, 2011
Sagittarius Cloud, a photo by DaemonGPF on Flickr.
Milky Way - Sagittarius region
120 sec x 20, no darks, no flats, no bias
Canon T1i + 50mm lense @ F/4.5
Piggybacked on my Vixen/CGEM rig and taken simultaneously with my QHY-9 image of M8 and M20.
Here's an annotated version:
Took this shot of M8 and M20 simultaneously with my QHY-9 through the Vixen ED80SF.
300sec x 14, darks, flats, bias applied
Thursday, May 5, 2011
Wednesday, May 4, 2011
No darks, no flats, no bias used. Thought it came out pretty good considering I had no prior experience with a DSLR. No award winning shots here, but for a non-serious attempt I think it looks promising. Hopefully 2nd attempt will be better.
Tuesday, May 3, 2011
After the stacking, I ran my usual initial data stretch and while the extended object detail was great, the background is a complete mess. Looks like a 4 yr old took a red, green, and blue crayon and layed them on their sides and filled in the background with it in swiping motions. I've never seen this issue in my OSC or Mono CCD astrocams. For grins, I also tried repeating the pre-processing using Deep Sky Stacker. EXACT same output. To diagnose a bit further, I repeated the process in DSS and Nebulosity but subtracting each of the calibration file types one by one. The problem doesn't seem to exist in the Darks, Flats, Bias. It's in the light frames. There is color noise/gradient apparent per each unstacked Light frame, but not consistent with the pattern apparent in the stacked exposures. None of the calibration files even reduce the effect in any way, shape, or form. The individual subs are increadibly noisey, as I had anticipated with an uncooled DSLR. But I had also assumed proper calibration and a large stack of quality light frames would have taken care of the problem. The extended objects and stars seem very smooth, but the background is horrific. I'm attaching a crop of the stacked result with a data stretch to help emphasize the effect I'm seeing. (When you expand the image, there are a few dark streaks, and I am aware that this is oversubtraction from darks not being perfectly matched. That part I know how to fix. The rest of the background effect is with no other post processing except a stretch to show it more predominantly.)