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100 subs was massive overkill, your images should be effectively noise-free with anything over 50 subs. I had one imaging "expert" berating me for not knowing anything about signal to noise ratio as I didn't take into account the gain in signal to noise with exposure time. Problem with signal to noise increase with exposure time is that the increase is not all that big, and also it flattens off rather quickly especially if your skies are not too good. So in my location the exposure time signal to noise ratio increase flattens off in about 5-minutes meaning that I am getting no (further) S/N ratio increase in the 20-minute exposures I need to take to get faint stuff and the only way I can get the noise down in galaxy or faint nebula images is to take LOTS of subs. The reason why I have often said you need at least 8-hours of good data to get a first class image is that if you take a typical sub length as 10-minutes and then have 50 of them, you're talking just over 8-hours. It only took me about 10 years to work this stuff out Greg P.S. Oh - and by the way - all your 50 subs have to be GOOD. You have to go through every sub and check they are o.k. as I now from experience you can actually see the degradation in the stacked image with just ONE bad sub in 100. P.P.S. And that is also the reason why I run multiple imagers in parallel - I increase the number of subs in a given time by the number of imagers. P.P.P.S. Dithering is essential. So is good image calibration with good flats and bias frames.
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I can't argue with that. I'm looking at ways to bring down my noise. I also take a vast number of subs, and through my C14 at 4000mm at F11, the tolerances for focus, tracking and guiding can become difficult during dozens of 5 minute exposures ( I bin (throw away) at least half of my subs). I'm going to start using dither more during my imagining runs as well. Ray
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That's just a case of getting the signal to noise ratio up in the first place which means LOTS of subs. When I first started imaging with the original Hyperstar I used to aim for 100 subs (although they were only 1-minute long). I used to get glassy clear completely noiseless images but they didn't go very deep. So it's a trade off. For things like star piccies you don't need a long exposure time - for things like galaxies and nebulae you do - this is one reason I prefer star piccies Greg
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Very noiseless and smooth Greg. May I ask how you process these to have what appears as zero grain. Ray
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Both epic work my friend. Ray
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Mizar & Alcor in Ursa Major taken with the Sky90 array. Greg
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That is very nice. Dave.
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And here's a Noel Carboni process of JUST the Sky90 data. Greg
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I combined all my Sky90 data of this object together with the DSS data from the same region. Barnard's "E" is a dark nebula lying close to the star Tarazed. How many stars do you think are in this image?? Registar says there are 165,000 Greg
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Playing about on Photoshop 2020 I put together everything I had on the Pelican nebula and then also added DSS data from the same region. Everything stitched together using REGISTAR. Greg
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Just curves plus Noel's "Enhance DSOs and reduce stars" Greg
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Love it Greg. What processing do you perform to bring out the dark neb? Ray
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This is a single frame with the Sky90 array.
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Managed to get Photoshop and all the associated bits onto a more up to date machine (HP Z600 workstation) as my main computer is slowly losing the plot. Did a test process on some Taurus molecular cloud data - 42 x 20-minute subs. Greg
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Been a while since I posted a photo, but having some spare time has allowed me to process some data I have. This was processed mostly in PI and some minor adjustments in PS. Shot at 4000mm, Focal Ratio F11, and probably spent about 50 hours acquiring the correct subs. The total imaging time used is more like 10 hours, but this object sits over the city lights from my observatory and many subs were unusable. C/C's welcome. Ray
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The Great Conjunction of the Century
wingeing Pom replied to timthelder's topic in DSLR and CCD Astrophotography
Great work!!!!!!!!!!!!!! A super record to have. Greg -
The Great Conjunction of the Century
Radar replied to timthelder's topic in DSLR and CCD Astrophotography
Lovely work Tim. She looked quite amazing through the eyepiece as well. Naked eye was just as good IMO. Something pretty special about seeing both of those objects so close in the eyepiece. Have a great Xmas my friend. Ray -
And, my best effort at the 'Great Conjunction of the Century'. It will still be a good view tomorrow night if one has the opportunity, (and the weather) to have a look. This one is from the 20th. And this is from the 21st. I used the C9.25 with my now old 450da and a 2x barlow lens I fabricated some time back. FOV was about right for this event. Cheers, Tim.
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I hope it sells quick mate. Need to get some cash back in the bank after paying for the van. Lol. Shane
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Very cool mate. We love camping. Great time to be selling with no international travel, it will sell extremely quickly. Ray
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Time has come to upgrade from the camper trailer to a caravan. Got the new (to us) caravan last Friday, now to sell the camper. Shane
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lol, Probably not the only one. Tim I was using IC Capture. My monochrome camera would freeze after 30 or 40 frames. I tried using firecapture to no avail. I've reinstalled the camera and IC Capture but same problem. I've updated my PC a few months back to Windows 10 on a quad core PC. It is lightning fast, but I have a feeling the camera (which is about 10 years old) is at fault. It is the first time I've tried planetary with this new PC and I really need to update the camera to do the faster PC justice. My 7 position filter wheel which is a nautilus is also rendered useless with Windows 10. Great filter wheel but no drivers seem to work on Windows 10. Interestingly for lurkers that visit here (about 500 per month), I did the get nautilus filter wheel working in The SkyX for about 30 minutes until it crashed TSX and wouldn't go back to a functional state. I still had a good time under the stars. Welcome to AP. Ray
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What program/programs are you using for processing? Seems like I remember hearing about this conundrum before. Tim
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Yep - I thought a monitor had suddenly died - it was actually the VGA splitter cable that fed the monitor, the monitor was fine. I now have a spare monitor on the way - and to top it all off - I didn't actually need the splitter cable. Think senility is setting in. Greg
