CCD-Freak

As I understand it the Offset is used to keep the bottom end of the Histogram from going below 0 which would be clipped. The default in the ASCOM driver is 70 which seems a bit high to me. I want to try some lower Offset values but I don't want to spend too much of my hard to come by clear sky time. The default value works fine so I will use that for now. One thing to remember....If you change the offset value you will need to shoot your Darks and Flats at the same setting. After looking at a stacked image of 2 minute subs I think the 70 Offset is good. John Love CCD-Freak WD5IKX

I build portable observatories called SkyBoxes but I am on the wrong side of the pond. )^8 John CCD-Freak WD5IKX

Here is a screen grab from AA7 of a single sub of M3 John CCD-Freak WD5IKX

So far I have not shot longer than 120 second subs with my ASI-533. At F3.8 many of the stars are saturated so I may try 60 second subs with that scope next time I have it out. I plan to use a 10" F4.7 Newt when I go out to New Mexico in October if it tests OK from my light polluted garden. I know what you mean about wasting "sky time". The ASI-533 is very sensitive.....This test image of M3 was only 10 second subs at F10 (60 x 10 seconds...10 minutes total) John CCD-Freak WD5IKX

I, like you, think there will be little difference lowering the offset so I have not been in a rush to experiment with it. I will continue to run the gain at 100 since that is where the low noise mode kicks in and the dynamic range and well depth are the highest. I am really happy with the ASI-533MCP so far and look forward to more "quality dark sky time" with it. John CCD-Freak WD5IKX

The default offset setting in the ASCOM driver is 70 which seems high to me and I plan to try going down to 50 or maybe as low as 20 but I will have to be careful not to clip the bottom of the histogram. Let us know how the 50 offset works. John CCD-Freak WD5IKX

I just got to dark sky test my new ASI-533MCP which is one of the newer No amp glow cameras and I am really happy with how clean the data is. This image of NGC281 is 30 x 120 seconds (1 Hour) Gain=100, -5°C with an 8" F3.8 imaging Newt from Bortle 2 skies. Captured and processed with Astro Art 7. This camera produces much cleaner data than the ASI-1600MC-Cool I had before. These CMOS cameras just keep getting better. John Love CCD-Freak WD5IKX

I was using the Sky Watcher Aplanatic coma corrector. the corners look good but I notice a circular halo on the brighter stars so I need to figure out where it is coming from. I have used this corrector on an 8" F5 and an ASI-1600MC and I did not notice it with that setup. I will be putting the ASI-533MCP on a 10" F4.7 Newt in the near future. Here is a pix of the setup for the NGC281 image. John CCD-Freak WD5IKX

I usually use a UV-IR filter but I was shooting this with a Newt astrograph so I did not put it on for this test run. John CCD-Freak WD5IKX

I finally got out to the dark site to try out my ASI-533MCP. This image of the Pac Man nebula NGC281 is 60 minutes total (30 x 120sec) Gain=100 @ -5°C I used an 8" F3.8 Newt at .98"/pixel. The ASI-533MCP is proving to be a sweet camera and I am looking forward to my imaging expedition to south west New Mexico this fall. John Love CCD-Freak WD5IKX

I finally got a chance to image from one of my favorite dark sites (Bortle 2). While ironing out computer and equipment issues I managed to get some images. The M17 image is only 16 minutes total !!! (8 x 2m) and NGC281 was a total of 60 minutes (30 x 2m) Gain=100 at -5°C with an 8" F3.8 imaging Newt. I am looking forward to my expedition to western New Mexico this fall. The ASI-533MCP is proving to be a sweet camera. John Love CCD-Freak WD5IKX

Try stacking the images without the flats and see if you still have the problem. I just downloaded the file you posted and it looks like a problem with your flats.

Did you calibrate with Darks and Flats? Looks like "dust doughnuts".

Where in Texas ???? I am way up in north Texas. John CCD-Freak WD5IKX

This is from last night. The moon is beginning to be a problem. 130 x 30 seconds at ISO-800 55mm f4

I got this image last night but the moon is starting to cause some problems and it not quite as bring as a few days ago. It will be interesting to see in a couple weeks after the moon rises late enough to not light up the sky. 130 x 30 seconds at ISO-800 55mm f4

I got this image a few nights ago and it looks like I might get another chance tonight.

Here is one from a couple nights earlier. 40 x 60 seconds at ISO-1600 and no clouds. Canon "Kit lens" at 85mm. Stacked and processed with Astro Art 7. The clear sky made a great deal of difference.

With some clouds about I managed 40 x 60 seconds at ISO-800 with a 55mm prime lens on my Canon DSLR. I used a driven mount so I did not have to worry about guiding since my exposures were short. This was stacked and processed with Astro Art7. Tonight I plan to use about 100 x 30" at ISO-800 to reduce the noise some.

Hey Steve Welcome to SGL They said the dark side has cookies....they will go well with the Blue Bell !!!!! 🤪 John "Fella Texan" CCD-Freak WD5IKX

Hello from a fellow Texan. Where are you located in central Texas ???? I am up in north Texas almost at the Oklahoma border. John CCD-Freak WD5IKX

I had a Meade ETX 125 with the Wegat mods and was very pleased with it. The lunar and planetary views were "most impressive". When placed on my CI-700 mount is was rock stable. I sold it in a fit of aperture fever and have regretted it ever since. 😪

I have a Meade 10" LX50 OTA and it performs well. It is very much heavier than an 8" so portability will suffer. I think the CGEM-DX will handle it OK. As you can see from the picture it is much larger than an 8" SCT so I put it on my AP900 mount. Great combo for visual.

Welcome.....You picked a great hobby. I got into astronomy 50+ years ago and it is still interesting. Me in 1969 as I remember. I look more like Santa Claus now. John CCD-Freak WD5IKX

As the lyrics of the Eagles song "Hotel California" say "you can check out any time...but you can never leave" 🤪 John CCD-Freak WD5IKX