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Fordos Moon

First Image of Jupiter with ASI120MM - advice please

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Morning All,

Last night I managed this image of Jupiter and I would appreciate your tips on how to improve it.

Equipment was 200P on HEQ5 with ASI120MM and Televue 2.5 powermate.

Captured in Firecapture beta. 60 seconds. 512x440. Gain 41. Exposure time 13.65. 72 fps. Gamma 26.

Processed in Virtual Dub, Castrator, AS2 and Registax 6.

Whilst content with the image for my first with the new camera, I know better will come.

My initial thoughts are:

1. Should I have taken a 2 minute AVI or is 4,300 frames enough?

2. Is the main problem I am out of focus and should work more on this next time?

3. I notice a slight onion ring. Have I overdone the sliders?

Your advice as always would be most appreciated.

Edited by Fordos Moon

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Not bad for a first effort with a new camera. I think there is a bit of onion-ringing going on, which can be a case of exposure or gain set too low. I use the histogram tool in firecapture to ensure about 80-80% of the ADC range is used. This helps a lot. Focus is always a hassle, and I use the moons quite a lot to judge focus. My best shots with the ASI120MC to date have been at F/20, so maybe you can go beyond the F/15 which you are using.

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Not bad for a first effort with a new camera. I think there is a bit of onion-ringing going on, which can be a case of exposure or gain set too low. I use the histogram tool in firecapture to ensure about 80-80% of the ADC range is used. This helps a lot. Focus is always a hassle, and I use the moons quite a lot to judge focus. My best shots with the ASI120MC to date have been at F/20, so maybe you can go beyond the F/15 which you are using.

Michael many thanks for this, and I will take "not bad for a first effort" quite happily. I will make a note to check out the firecapture histogram - thanks again!

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Michael many thanks for this, and I will take "not bad for a first effort" quite happily. I will make a note to check out the firecapture histogram - thanks again!

My first capture with the ASI120MC was a good deal worse.

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Looks ok looks soft to me focus seems a tad of but all round looks like a first attempt I would not worry.mine was nothing like this just a ball with a couple a bands on it, I do not have this camera so not sure if the settings are right or wrong but a good first image

Pat

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I agree.

The histogram is very useful for balancing gain and exposure.  I tend to select the exposure to get the frame rate I'm after, then adjust the gain to get a suitable histogram.  If that means the gain is much getting over 60% then I may well think about increasing the exposure time.  It is all a bit "touchy feely" though.

Focus is, well, practice and more practice really.  Motorised focusers help enormously because there's no wobble when the focuser is moving.  It made a huge difference when I made one for the 127 Mak and I'm in the process of making one for my PST before doing one for the C9.25.  I seem to have done well with motor focusers.  Despite the two mounting brackets they're supplied with I've had to make a bespoke bracket for all of mine :)

James

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I agree.

The histogram is very useful for balancing gain and exposure.  I tend to select the exposure to get the frame rate I'm after, then adjust the gain to get a suitable histogram.  If that means the gain is much getting over 60% then I may well think about increasing the exposure time.  It is all a bit "touchy feely" though.

Focus is, well, practice and more practice really.  Motorised focusers help enormously because there's no wobble when the focuser is moving.  It made a huge difference when I made one for the 127 Mak and I'm in the process of making one for my PST before doing one for the C9.25.  I seem to have done well with motor focusers.  Despite the two mounting brackets they're supplied with I've had to make a bespoke bracket for all of mine :)

James

James - thanks for popping in! Are the required frame rates and histogram shapes trial and error or has a good starting point been established? I must invest in a motorised focusser one day.

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James - thanks for popping in! Are the required frame rates and histogram shapes trial and error or has a good starting point been established? I must invest in a motorised focusser one day.

I'd say the histogram is important to get close to right whether it's 70% or 80% won't kill you, but if you don't have enough dynamic range in the image then you'll be struggling for data to process.  Frame rate is up to you really, but anything between 30fps and 60fps is probably reasonable.  Fast is good, but requires more gain and gain means noise, so again it's something of a balancing act.

James

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I agree.

The histogram is very useful for balancing gain and exposure.  I tend to select the exposure to get the frame rate I'm after, then adjust the gain to get a suitable histogram.  If that means the gain is much getting over 60% then I may well think about increasing the exposure time.  It is all a bit "touchy feely" though.

Focus is, well, practice and more practice really.  Motorised focusers help enormously because there's no wobble when the focuser is moving.  It made a huge difference when I made one for the 127 Mak and I'm in the process of making one for my PST before doing one for the C9.25.  I seem to have done well with motor focusers.  Despite the two mounting brackets they're supplied with I've had to make a bespoke bracket for all of mine :)

James

i like to see the results of the motor for the 9.25 James, been thinking of trying to do something for my 8" sct without paying crazy money for a tailored motorised focuser,

as for you jupiter image, that certainly isn`t too bad, did you try the wavelets in registax to sharpen the detail any ?

my first effort with the mono asi 120 was about just as good as yours, i was trying the filters aswell to get a coloured image, you have to be quick, 30 seconds on each colour and i luminance with a manual filter wheel, very tricky L.O.L.

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as for you jupiter image, that certainly isn`t too bad, did you try the wavelets in registax to sharpen the detail any ?

.

I did use the wavelets Red, but even with the top one at 100% it would not sharpen any more, which confused me somewhat and made me think I was out of focus.

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I did have a go at capturing Mars but it appeared very very wobbly (fairly low in sky i know), perhaps something beyond my ability and equipment? But will try again! 

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i like to see the results of the motor for the 9.25 James, been thinking of trying to do something for my 8" sct without paying crazy money for a tailored motorised focuser,

I do have an external focuser on the C9.25 which should make things a little easier when it comes to motorising than my 127 Mak where I drive the focuser knob directly.  It's only a Revelation dual-speed R&P model though.

My experience with the Mak was that the mirror slop when changing focuser direction was enough at long focal lengths to take the image entirely off the sensor, but I didn't want to fit an external focuser there because the extra backfocus would have made the effective focal length too long for the Moon and Sun discs to fit on my DSLR sensor (perhaps I should get a full-frame camera :D

I'm unlikely to use the C9.25 for full disc lunar and solar though, so the external focuser removes the mirror problem and hopefully makes for a simpler motorisation mod as well.  I've started with the PST first though as I have the crayford focuser on that and there are at least screws to fit a bracket with.  The R&P model has a dearth of potential mounting points, so I need to engineer an alternative for that.

James

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Played around with the wavelet sharpening option, although could do with a guide to be honest!

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