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Jupiter & Saturn – 7/13/2020 – Celestron C11 First-Light

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#1 jgraham

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Posted 13 July 2020 - 05:46 PM

Telescope: Celestron C11 @ f/20, Orion Atlas EQ-G
Camera: ZWO ASI294MC (uncooled), OPT 2” 2x Barlow
Filter: Highpoint Scientific IR Filter
Seeing: fair, 3/5
Jupiter: 1h12m EDT; 3,000 (of 4,000) x 75ms, gain 200, saved as SER
Saturn: 1h20m EDT; 2,250 (of 3,000) x 100ms, gain 300, saved as SER
White Balance: Nebulosity Automatic
Software: SharpCap Pro, AutoStakkert, Registax, Nebulosity, Photoshop

 

Jupiter (7-13-2020 01h13m EDT)-1j.jpg

 

Saturn (7-13-2020 01h22m EDT)-1j.jpg

 

I bought this 1994 C11 late last fall specifically for high resolution lunar and planetary images and after a lengthy refurbishment that included a complete tear-down to fix an issue with the primary mirror (turned out to be a loose locking collar), re-greasing the slide (Brand new coating of Mobil 1), and adjusting the collimation, I _finally_ had an opportunity to give it its first real test. I dedicated all of last night to just getting it set up, all the pieces aligned, and the camera focused; getting a useable set of images was a bonus! The collimation needs to be fine-tuned, but these initial results are very encouraging.


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#2 happylimpet

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Posted 13 July 2020 - 05:51 PM

Great stuff! Forgive me if you know this but the exposure times youve used are very long and much sharper results will be gained with shorter... 3 to 30 ms is probably the range to explore. Also stacking a smaller percentage will help (in the range 1% to 30% usually for me, more like 20 for the gas giants, lower for Mars/Mercury/Venus). Again, sorry if you already know this!


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#3 yock1960

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Posted 13 July 2020 - 06:32 PM

Congrats John! I don't enjoy setting up a new scope, but I do enjoy using it, when it is setup! lol.gif

 

I have to agree with Nick. I'm shooting a little longer than you and my gain for both was about 100 more. More like 325, for Jupiter. Of course, I'm using the 224MC.

 

Steve


Edited by yock1960, 13 July 2020 - 06:34 PM.


#4 jgraham

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Posted 13 July 2020 - 06:47 PM

Heh, heh, everyone has their own secret sauce, these are mine. I always stack 10%, 25%, 50%, and 75%; the later is always the best for me. Shorter exposures _may_ give better results, but I have found that my images are pretty much always limited by seeing. You can only do so much with 30 degrees of elevation on a warm muggy night. :)

This t'ain't my first rodeo. :)

Enjoy!

#5 jgraham

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Posted 13 July 2020 - 06:52 PM

I've also got the 224 and the 290 (and the 1600MM cool). I previously did some tests with the 294 on the moon and I was very impressed with how well it performed. The large chip comes in handy for locating the field, and then I switch to ROI to kick up the frame rate. Tracking was excellent during these runs.

Love it!

 

P.S.

 

I almost forgot...

 

These just happened to be the very first sequences that I grabbed intending only to use them as test images. Somehow I got lucky. As soon as I grabbed these two sets I had a few minutes before Jupiter reached the meridian (I can only image on the east side of the meridian from my hose) so I went back and turned the gain up to 300 and turned the exposure down to 25ms on Jupiter and 50ms on Saturn. I also grabbed 5-minute and 10-minute sequences of Saturn. I stacked 10%, 25%, 50%, and 75%. None of these were sharper than the first set that I show here. The problem; in 10 minutes the seeing went from fair to something less than fair. The shorter stacks sometimes look sharper than the longer stacks, but its an illusion as these stacks tend to have a higher degree of high frequency noise. If I blink the images, the longer stacks actually show more fine detail and less noise, though the overall image may look a tad softer because of the lower high frequency noise. Just for yucks I might spend some time looking at the FFTs for some of these data sets. Regardless, the final results are soooo much just the luck of the draw as to what seeing is going to give us. 

 

The Plan moving forward is to spend some time zeroing in the collimation, sneak the gain up, the exposure down, increase the number of subs, and re-learn how to use WinJuPos (it has been a while). Heh, heh, some of the best planetary imaging that I have ever done was using my SC8 at f/30 using my trusty old DBK21. Of course the ecliptic was a _lot_ higher back then. I'm love'n this C11 and the ASI294MC and I'm gonna stick with'm all the way through Mars season. Surely I can do better with this gear than my old LXD75 SC8 & DBK21! :)

 

One night at a time...

 

Have fun folks!


Edited by jgraham, 13 July 2020 - 07:34 PM.


#6 sunnyday

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Posted 13 July 2020 - 08:06 PM

very nice shots , thanks .



#7 jgraham

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Posted 14 July 2020 - 12:32 AM

Coolness. I'm looking at Jupiter right now. Seeing is pretty rough, so it's a good night to experiment. I cranked the gain up to 400 and lowered the exposure to 10ms. The histogram is about 75%. Jupiter is just about at the meridian at an altitude of 28 degrees. It looks like I'll get about 20,000 frames to play with.

On to Saturn!

:)
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#8 jgraham

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Posted 14 July 2020 - 12:49 AM

Saturn; gain 400, 30ms, histogram 60%-ish, seeing awful (flag waving as Steve would say). 10 minute sequences, no drops, 29 degrees altitude, 20,000 frames.

One more run, and then back to bed!

:)

#9 jgraham

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Posted 14 July 2020 - 12:51 PM

Ugh. Saturn turned out fair, Jupiter not so good. You can't make a silk purse out of a sow's ear. :/

One more night, then it's back to deepsky imaging until the moon returns.

So much to see, so few clear nights. :)


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