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Solar Imaging Question - Lunt

Started by jassan , Mar 31 2023 08:13 PM

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4 replies to this topic

#1 jassan

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Joined: 02 Mar 2012
Loc: Silver Spring, MD

Posted 31 March 2023 - 08:13 PM

I need some insight here. When I image the Sun I do not have a full disc, which is fine for me, but perhaps that part of the issue. The issue is that I will have the sort of off center darkening of my image and I am not certain how to avoid that. I have a Lunt 100Tha, ASI533mm and 174mm and use a tilt adaptor to deal with Newton's rings, but this darkening I do not know the source of, whether it is rooted in the pressure tuning and/or the fact I am dealing with diagonal in my imaging train? I'm under the impression I need the blocking filter in even when imaging. I can generally smooth this out with auto-toning in PS, but if this is something I can fix during imagining I would like to know how. Below is an example from the other day. Notice the bottom left of the image.

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#2 MalVeauX

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Loc: Florida

Posted 31 March 2023 - 08:18 PM

Hi,

You're seeing uniformity issues, generally from tuning. It takes very gentle great care to get tuning just right so that the disc is uniform. It's easy to not see it at first until later you go to push contrast hard and then you notice it. So first and foremost I would suggest practicing uniformity tuning so that the live view is recognized and not just later after you process. If all else fails, until you get there, a flat calibration would have handled the brightness differences (but doesn't fix bandpass uniformity issues).

Very best,

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#3 marvyyk

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Loc: St-Jean-sur-Richelieu, Quebec

Posted 31 March 2023 - 08:23 PM

Wow, amazing!

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#4 jassan

Explorer 1

topic starter

Posts: 91
Joined: 02 Mar 2012
Loc: Silver Spring, MD

Posted 31 March 2023 - 08:34 PM

Hi,

You're seeing uniformity issues, generally from tuning. It takes very gentle great care to get tuning just right so that the disc is uniform. It's easy to not see it at first until later you go to push contrast hard and then you notice it. So first and foremost I would suggest practicing uniformity tuning so that the live view is recognized and not just later after you process. If all else fails, until you get there, a flat calibration would have handled the brightness differences (but doesn't fix bandpass uniformity issues).

Very best,

So it is on the tuning, thank you for that!