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Old 19-09-2019, 08:38 PM
morls (Stephen)
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Jupiter and Saturn 18-09-19

These were taken with a 180 Mak, ASI120MM-S and 2x Powermate. I followed a guide I found online which recommended a gain of around 70% for Jupiter and 90% for Saturn, but I found a lot of noise when doing wavelets in Registax. This article was written a number of years ago, and I don't think the ASI120 needs to be pushed as hard.
It's my second night out with the gear, and I realise it's going to take some time to get a feel for balancing gain and exposure. I was pretty happy to get up to around 140fps in a MONO16 colour space, with a capture area of 640x480.
I might be being a bit unrealistic at this beginning stage, but to me the images seem a bit soft. I'm not sure whether it's the focusing, too much gain or bad processing. I guess I'll just keep at it and get some experience with the basics.
Thanks for looking
Stephen
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Old 19-09-2019, 10:02 PM
foc (Ross)
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Good images,
You are getting some nice detail there. I like to see Mak images.

I have hardly ever used mono cameras and when I have, I have found it more difficult to focus on surface features on Jupiter than color but your focussing technique might well be better than mine. Seeing is so variable that I would need to try much more often to conclude whether the camera was really harder to focus with and perhaps that is the case with you and this outing that just once is not enough data.

Still, I use firecapture and if I were to try for what sounds like a quite large ROI (much larger than the planet itself) with a 2x barlow on a C6 or C8 but get such high frame rates it would mean my gain and sensitivity were set too high and this could also be the source of your noise. I commonly use a 1.5 barlow in this late stage of opposition and typically poorish seeing conditions that have often accompanied Spring in my local area. I usually use a 'neutral' gain and low sensitivity in Firecapture but I do not know if this applies with your capture software.

Your slower optics (relative to a standard Cat), makes a 2x barlow seems quite ambitious unless seeing is extremely good where you are and even then that might feature some degree of 'empty' magnification. You might instead find it worth to try with no barlow initially and consider a 1.5X Barlow as a step up if conditions are very good. And of course depending on its design a 1.5 or 2x Barlow may not give exactly that magnification when a planetary camera is inserted into it, the power mates though do have provision for an exact position at least with my 2.5 powermate..
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Old 20-09-2019, 08:07 AM
morls (Stephen)
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Thanks Ross. Your point about the seeing being a factor when using 2x powermate is spot on I think.
Luckily I did some imaging without the powermate at the start of the session, and there seems to be more detail in these. I'm playing around with processing, and havetried using autostakkert without normalisation or sharpening, and I think this is helping. My reasoning is that registax does sharpening, and I don't want to process twice.
Here are some more images, taken without powermate, and processed in a number of ways using autostakkert and registax. They're noisy, but I wanted to go for detail and so held back on the de-noising in registax.
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Click for full-size image (20_12_03_Jupiter_grad4_ap12.png)
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Click for full-size image (20_12_16_Jupiter_grad4_ap12.png)
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Click for full-size image (20_12_16_Jupiter_grad4_ap12_Drizzle15.png)
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Click for full-size image (20_12_30_Jupiter_grad4_ap17.png)
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Old 20-09-2019, 09:33 AM
foc (Ross)
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Yes, the images without powermate look much better. Jupiter is only giving smallish windows now when it is not dropping below 30 degrees. I think you have done very well against the challenges is now poses. I can see nice definition of a small oval or moon for example on the face of Jupiter. Away from Jupiter your moon is not quite round, could be seeing, maybe thermals, or capture length and not sure if you are using an equatorial mount or an Alt-AZ mount but as long as the mount is stable enough with your heavy optics during probably gusts of breezes you can get some nice captures.
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Old 20-09-2019, 09:40 AM
morls (Stephen)
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Thanks Ross. Using an NEQ6 Pro.
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Old 21-09-2019, 11:26 AM
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mental4astro (Alexander)
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STEPHEN!

Did you notice the hint of the Encke Division in your Saturn pic!!! If the image is a little sharper, the Encke Division would be better resolved. But it's there, neat and unbroken on both sides!

Looks like you've got yourself a damn find Mak!!!

Not many pics of Saturn show the Encke Division, even from larger aperture scopes than your 7" Mak.

Alex.
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Old 21-09-2019, 07:22 PM
morls (Stephen)
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Hi Alex,
I did notice, and was both happy and relieved to see it. Before taking these images I changed out the stock collimation screws, replacing them with longer versions which I can adjust by hand (they are M5 threads). It took a while to understand what was happening in the eyepiece as I made adjustments - it's certainly not the same as collimating a reflector! - but it's getting there. I think there's still some improvement possible, but it's definitely moving in the right direction.
Stephen

Last edited by morls; 22-09-2019 at 07:04 AM. Reason: moved discussion of modification
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