Lunt60T Ha Double stack issue

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Petrus
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Lunt60T Ha Double stack issue

Post by Petrus »

I have been trying to figure out how to double stack my Lunt60THa solar telescope with 60 mm doublestack filter. So far I have not reached zen kind of state of mind with this filter. I tried to make marking on filter and telescope during last imaging session, as I assumed I almost had everything right. Since spring time I have kept trying during good seeing and personal mood. Solarchat offered little comfort, and now I seek your guidance!

Here is one test result with Lunt60THa + 60 mm double stack and ASI178MM. No flats or tilt adapter. In this picture I get least "banding issue", so is it just more filter position adjustment needed? I can see contrast improve on live screen when I adjust doublestack filter's position.

Image

In case there might be some kind technical issue, here is how solar telescope itself perfroms, ,same observation day.
Below is image with single stack setup, with barlow and flat used. Otherwise same gear (Lunt60THa, Powermate barlow 2.5x, ASI178MM).

Image

Any kind of help is valuable, just like this double stack filter was :D


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LS80THa DSII - Calcium II K module 12mm - Lunt Herschel wedge 1.25" - Quark Chromosphere - Solarscout Quark - Sol'Ex
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Re: Lunt60T Ha Double stack issue

Post by DeepSolar64 »

Sassy,
It looks like you are tuned to the " surface " features and may be a little off band for the filaments. I have trouble giving you advise on this because I have the same problems you do with tuning with double stack concerning imaging. I tend to tune first visually before putting the camera on but even then the camera often shows uneven illumination which doesn't often seem to show up as much visually so I will go tweaking the etalons. I find it so hard to get it right with DS and imaging. I'll often get frustrated and go single stack which is much easier to tune.

I know I am no help. Sorry.

James


Lunt 8x32 SUNoculars
Orion 70mm Solar Telescope
Celestron AstroMaster Alt/Az Mount
Meade Coronado SolarMax II 60 DS
Meade Coronado SolarMax II 90 DS
Meade Coronado AZS Alt/Az Mount
Astro-Tech AT72EDII with Altair solar wedge
Celestron NexStar 102GT with Altair solar wedge
Losmandy AZ8 Alt/Az Mount
Sky-Watcher AZGTI Alt-Az GoTo mount
Cameras: ZWO ASI178MM, PGR Grasshopper, PGR Flea
Lunt, Coronado, TeleVue, Orion and Meade eyepieces

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Re: Lunt60T Ha Double stack issue

Post by EGRAY_OBSERVATORY »

James has recognized the issue with DS-ing your LS60 and DS60.
I have exactly the same set-up as yourself (in Finland) and although currently I am not using the DS, I know that tuning of both Etalon's can be a challenge to get the "sweet-spot" - it simply requires more practice.

Bear in mind that for prominences, single-stacking gives the best result, whereas DS-ing is primarily for better surface detail and it's contrast for that purpose...

Some have recommended turning the DS in the scope by a suitable amount (with care not to loosen it too much of course) and by stages of that, take more images to see if it corrects the situation. If that proves successful, then to count those turns from fully-in and mark both sides of the DS and scope for future use..

Also to inspect the DS to make sure there is no apparent 'fogging' of the optics. The DS itself should always be kept in a dry atmosphere in its' case and with a Silica Gel pack when not in use for any lengthy- period...

I hope these two points will give you a satisfactory-resolve to your issue.

Terry


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Re: Lunt60T Ha Double stack issue

Post by Petrus »

Thank you James and Terry! I will continue with my trial and error. I do have M6 rotator wich helps finding correct position without risk of dropping the double stack filter itself. I tested without and with it.

I agree single stack Lunt60 is just most fun way for casual or long period imaging. I miss those not so hot early summer days...!


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Re: Lunt60T Ha Double stack issue

Post by EGRAY_OBSERVATORY »

Yes, here in S.E.England, it generally has been wet and cloudy, cold or too-cold, foggy, windy or very windy and very occasionally far too hot, but there's not much we can complain about really - cus no-one will listen...!!!

Cheers
Terry


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Re: Lunt60T Ha Double stack issue

Post by Martin_S »

Sassy, as James has stated you look off band slightly on your single stack image. I would follow the advice that Terry has suggested.
Here are my suggestions.

Remove your front etalon and fine tune your rear etalon until you get the most contrast on your solar disk. Lower your exposure to reveal as much detail on the disk as possible. You should then see the spicule layer on the edge of the disk(you wont see it when double stacked). When you are satisfied with your image put the front etalon on your scope and fine tune your front etalon for the best contrast, you may have to rotate the etalon to reduce banding. In single stack you can also do off band imaging to emphasise different solar features.
Here is a live capture from last week.

Martin
lnt.JPG
lnt.JPG (409.32 KiB) Viewed 325 times
Last edited by Martin_S on Mon Jun 21, 2021 12:09 pm, edited 1 time in total.


H alpha : ,Skywatcher 120mm F8 open frame refractor, a tilted 2" 7nm H-alpha filter as a sub energy rejection filter, Baader TZ4 telecentric focal extender, Player One energy rejection filter, Combo Quark Chromosphere, Naked PST etalon for double stacking, ASI74mm camera
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Re: Lunt60T Ha Double stack issue

Post by Petrus »

Martin_S wrote: Sun Jun 20, 2021 9:34 pm Sassy, as James has stated you look off band slightly on your single stack image. I would follow the advice that Terry has suggested.
Here are my suggestions.

Remove your front etalon and fine tune your rear etalon until you get the most contrast on your solar disk. Lower your exposure to reveal as much detail on the disk as possible. You should then see the spicule layer on the edge of the disk(you wont see it when double stacked). When you are satisfied with your image put the front etalon on your scope and fine tune your image for the best contrast, you may have to rotate the etalon to reduce banding. In single stack you can also do off band imaging to emphasise different solar features.
Here is a live capture from last week.

Martinlnt.JPG
Wow! Thank you a lot Martin! I hope I could get better results with this help. I will post results when I get some some H-alpha time.


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LS80THa DSII - Calcium II K module 12mm - Lunt Herschel wedge 1.25" - Quark Chromosphere - Solarscout Quark - Sol'Ex
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Re: Lunt60T Ha Double stack issue

Post by DeepSolar64 »

Thanks Martin. I will utilize your advise too!

James


Lunt 8x32 SUNoculars
Orion 70mm Solar Telescope
Celestron AstroMaster Alt/Az Mount
Meade Coronado SolarMax II 60 DS
Meade Coronado SolarMax II 90 DS
Meade Coronado AZS Alt/Az Mount
Astro-Tech AT72EDII with Altair solar wedge
Celestron NexStar 102GT with Altair solar wedge
Losmandy AZ8 Alt/Az Mount
Sky-Watcher AZGTI Alt-Az GoTo mount
Cameras: ZWO ASI178MM, PGR Grasshopper, PGR Flea
Lunt, Coronado, TeleVue, Orion and Meade eyepieces

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Re: Lunt60T Ha Double stack issue

Post by EGRAY_OBSERVATORY »

Many thanks Martin for your additional information on how to.

Terry


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Re: Lunt60T Ha Double stack issue

Post by Martin_S »

Thanks Terry and James, please note that I have edited my original post , I have substituted the word "image" with "front etalon" .

Martin


H alpha : ,Skywatcher 120mm F8 open frame refractor, a tilted 2" 7nm H-alpha filter as a sub energy rejection filter, Baader TZ4 telecentric focal extender, Player One energy rejection filter, Combo Quark Chromosphere, Naked PST etalon for double stacking, ASI74mm camera
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