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Old 17-10-2020, 04:43 PM
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multiweb (Marc)
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Mars 10/10/2020

I have a loop here and a still shot of three frames derotated in WinJUPOS.

That batch is from Saturday night last week. Got some clouds yay!... Still working on colors.
Not sure how to grade the seeing by numbers but I still had a bit of issues focusing so it mustn't have been too good.
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Old 17-10-2020, 08:10 PM
Dennis
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Nice work Marc, you're really pumping out those Mars images.

Cheers

Dennis
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Old 18-10-2020, 09:13 AM
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multiweb (Marc)
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Thanks Dennis. Still chasing that elusive focus. I'm faced with 3 options.

1- The seeing is not good enough. (possibly)
2- The scope is slightly out of collimation. (unlikely)
3- I still suck at focusing. (very likely)
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Old 18-10-2020, 10:06 AM
Dennis
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Quote:
Originally Posted by multiweb View Post
Thanks Dennis. Still chasing that elusive focus. I'm faced with 3 options.

1- The seeing is not good enough. (possibly)
2- The scope is slightly out of collimation. (unlikely)
3- I still suck at focusing. (very likely)
Hi Marc

Out of the 3 possibilities you have listed, my experience has been that #1 (seeing, or lack of) is the single biggest contributor to soft images.

Cheers

Dennis
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Old 19-10-2020, 08:47 AM
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Originally Posted by Dennis View Post
Hi Marc

Out of the 3 possibilities you have listed, my experience has been that #1 (seeing, or lack of) is the single biggest contributor to soft images.

Cheers

Dennis
Too kind. I have my eyes on Tuesday night here to do some more testing.

So here's the plan. Use an IR cut this time, downloaded the beta version of FC v2.7 and pay attention to histograms, white balance and capture format.

Also want to nail the focus this time regardless of the conditions.
I did a bit of testing indoors and figured it's easier for me to nail it visually looking at a monochrome bayered viewport rather than a color loop.

Also going to try the ROI cut-out with image stabilization. Another thing I lacked was contrast for fosusing and never considered using the Gamma slider for this. As long as I remember to disable it once I'm recording.

So watch this space. Either I come back with a nice sharp pic or you'll hear a faaarke in the early morning fog coming from western Sydney.
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Old 19-10-2020, 10:15 AM
Dennis
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Hi Marc

For lunar and planetary imaging, I usually slew to a nearby star and put the Bahtinov mask over the OTA and focus on the star.

I then slew back to the target.

Cheers

Dennis
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Old 19-10-2020, 10:28 AM
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I did try that on Antares then slewed to Jupiter and found I was a little out. So either my baht mask wasn't precise enough for that FL or I didn't focus accurately enough. I realise you can focus by small increments which might be fine for deepsky with a mask because you can see the changes in the pattern but I find it useless on Planetary. I need to go in and out of focus and travel quickly through the sweet spot to judge where it is. When everything is wobbling and bouncing around I'd be buggered to notice if my current focus is better or worse than the previous step I was at. There's nothing obvious to me visually to compare. I don't know how people can judge this. Maybe experience. But catching that fleeting moment in the soup and say "yeah, I'm in focus now" well, that's not my forte.
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Old 19-10-2020, 10:48 AM
Saturnine (Jeff)
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Hi Marc

As Dennis said, nice work, enjoying yours and everyone else' planet images.

I seem to have similar difficulties to yours when it comes to focusing, the main one I put down to the seeing conditions.
Have checked and rechecked the collimation and take much care in trying to get best focus. My method, using SharpCap, is simply watching the enlarged image on the screen while twiddling the fine focus knob. With Jupiter it is mostly getting the moons as sharp a point as I can discern, though that is sort of wrong because at the focal length I'm using with the 10" newt, the moons are actually tiny discs not points, like the stars.
Tried using a motorized focuser but it didn't really seem to make finding best focus any easier than manually. Maybe i should try a Bahtinov Mask and see if it helps but don't have one to fit the scope, yet.
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Old 19-10-2020, 11:22 AM
Dennis
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Originally Posted by multiweb View Post
I did try that on Antares then slewed to Jupiter and found I was a little out. So either my baht mask wasn't precise enough for that FL or I didn't focus accurately enough. I realise you can focus by small increments which might be fine for deepsky with a mask because you can see the changes in the pattern but I find it useless on Planetary. I need to go in and out of focus and travel quickly through the sweet spot to judge where it is. When everything is wobbling and bouncing around I'd be buggered to notice if my current focus is better or worse than the previous step I was at. There's nothing obvious to me visually to compare. I don't know how people can judge this. Maybe experience. But catching that fleeting moment in the soup and say "yeah, I'm in focus now" well, that's not my forte.
I have an ESATTO Motorised Focuser that has focus steps of 0.04 microns, so what I do is step the focuser in 1,000 steps at a time until the Bahtinov Spikes just appear OOF, then I note the Step Position/Count.

Next, I step the other way (out) until I reach a similar OOF position and note that Step Position/Count.

I then take the mid-point of these IN/OUT Positions/Counts and Go To that number, putting me in the middle.

Using a Tak Extender x1.6 on the M210, with my ASI1600MM, the Critical Focus Zone is some 840 microns and with a x2 Powermate it becomes 1300 microns which allows for quite a large tolerance. Using at x2.5 Powermate to give me 7,000mm would give a CFZ of 2,000 microns.

Calculator here:

http://www.wilmslowastro.com/software/formulae.htm

Cheers

Dennis
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Old 19-10-2020, 12:20 PM
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multiweb (Marc)
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Quote:
Originally Posted by Dennis View Post
I have an ESATTO Motorised Focuser that has focus steps of 0.04 microns, so what I do is step the focuser in 1,000 steps at a time until the Bahtinov Spikes just appear OOF, then I note the Step Position/Count.

Next, I step the other way (out) until I reach a similar OOF position and note that Step Position/Count.

I then take the mid-point of these IN/OUT Positions/Counts and Go To that number, putting me in the middle.

Using a Tak Extender x1.6 on the M210, with my ASI1600MM, the Critical Focus Zone is some 840 microns and with a x2 Powermate it becomes 1300 microns which allows for quite a large tolerance. Using at x2.5 Powermate to give me 7,000mm would give a CFZ of 2,000 microns.

Calculator here:

http://www.wilmslowastro.com/software/formulae.htm

Cheers

Dennis
That's a good way to do it if you have a very precise focuser. I doubt mine would cut the mustard given backlash as well but I like the approach by the numbers. I need to do it visually though because I have to tweak the focus during the session as well.
PS: according to the calculator my CFZ is 3594 microns

Last edited by multiweb; 19-10-2020 at 12:51 PM.
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Old 19-10-2020, 12:22 PM
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Quote:
Originally Posted by Saturnine View Post
Hi Marc

As Dennis said, nice work, enjoying yours and everyone else' planet images.

I seem to have similar difficulties to yours when it comes to focusing, the main one I put down to the seeing conditions.
Have checked and rechecked the collimation and take much care in trying to get best focus. My method, using SharpCap, is simply watching the enlarged image on the screen while twiddling the fine focus knob. With Jupiter it is mostly getting the moons as sharp a point as I can discern, though that is sort of wrong because at the focal length I'm using with the 10" newt, the moons are actually tiny discs not points, like the stars.
Tried using a motorized focuser but it didn't really seem to make finding best focus any easier than manually. Maybe i should try a Bahtinov Mask and see if it helps but don't have one to fit the scope, yet.
Thanks Jeff. I have asked in the Sharpcap forums if they have a ROI stabilization method. The beta might but I haven't tested it yet. FC does have it and also a cut-out ROI which is very neat so you should try the beta version 2.7.
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