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Maximizing solar imaging with current equipment.

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#1 Borodog

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Posted 11 April 2021 - 09:20 PM

Hello. I'm very new to solar imaging and have many dumb questions, some of which have already been kindly answered by posters here. I'll keep this brief. I am what I would call an intermediate planetary and lunar imager and processor. I am familiar with capturing (I use SharpCap Pro), stacking (I use Autostakkert), creating mosaics (I use ICE), basic processing (usually limited to resizing, deconvolution, sometimes denoising, color correction, curves & gamma, suplementary sharpening, etc. in Astra Image) for both planetary and lunar. I'm familiar with the taking and use of calibration frames, and thanks to members here I now know how to shoot flats for solar.

 

My equipment for solar is ill-suited for the task, I know, but it is what I have and I don't really have the budget to produce the kind of spectacular images I see others posting here. But I would like to know where I should set my expectations so that I'll know when there is something amiss and I can improve on vs. when there is just something that is beyond the capability of my equipment. So, without further ado, my equipment for solar is:

 

1) 1977 orange tube Celestron C90. It is a very old scope and they often seem to get a bad rap, but it is in good condition and seems capable of producing decent images of objects in the sky that are about the angular diameter of the Sun: https://www.cloudyni...6100_558881.png

2) Thousand Oaks solar filter.

3) Should I choose to use it, I have an SCT threaded Crayford dual speed focuser that lets me fine focus without touching the C90's focus ring. It also puts the focal length at the as-advertised 1000mm. I can shoot anywhere from 800 to the advertised 1000mm without it, depending on the exact camera, adapter, and spacer choice. Honestly I have not seen much benefit from fine focusing with the Crayford, however (see below).

3) A few different cameras. The one I am planning on using mostly is an ASI183MC, 15.9mm diagonal 20 Mpxl 19 fps dedicated color astro cam (I understand mono is better for solar, but again, it's what I have).

 

So the question is not really how do I do this or that, the question is, what exactly should I expect from solar imaging with this equipment in white light? Because what I've seen so far, admittedly using a very, very different camera (Sony a6000 mirrorless, APS-C sized sensor, very low numbers of frames) has not been all that impressive. The only hint of surface detail I have seen so far has been a tiny smudge of an admittedly not-quite-in-focus itty bitty sunspot. Should I expect to be able to resolve convection cells with this scope if I am in focus? Should I be able to see prominences? Because other than some lumpiness around the perimeter I haven't seen anything like that. Are there usually prominences? Or are they intermittent and you have to get lucky to catch them? Do you have to stretch the perimeter like a DSO to see them?

 



#2 descott12

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Posted 11 April 2021 - 09:52 PM

In white light you will not see prominences. That takes an entirely different setup.

At best you will see sun spots (there are few now but they are very small). 

As far as surface detail, you may see granulation which is an "orange peel" like pattern. But this all depends on good focus and good seeing conditions. Seeing during the day is typically much worse than at night. And using too much aperture will not help. Your C90 is already getting a little big so you may need to mask it down. 

 

In the past, I have gotten some decent white light images (attached) but I have been failing miserably over the last few months (I believe due to poor seeing). I is sort of a crap shoot - you just need to keep trying.

 

Overall, the sun is pretty boring in white light. All the action is in H alpha.

 

Definitely give it a try with what you have. I is still fun and the sun is always changing so you never know what you may see.

 

Attached Thumbnails

  • 00238.jpg
  • 00367.jpg

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#3 Borodog

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Posted 11 April 2021 - 10:25 PM

Thank you, Dave! That is exactly the sort of information I am looking for. I will keep the expectations low.

 

A couple of follow-up dumb questions.

 

1) Can you use a regular (as in for DSO use) H alpha filter in combination with the aperture solar filter? Or must you use special solar H-alpha filters?

 

2) What about IR? I have a really quite crappy older technology astro camera that I've experimentally converted to IR. The filter basically looks like a solar filter; it's mirrored. I can't use it in this scope (nominally f/11) to image the Moon because it isn't bright enough. Can this be used to image the sun without the aperture solar filter, perhaps masked down to up the focal ratio even further, and would there be any benefit seeing and detail wise to imaging in IR for solar?

 

Thanks again for your time.


Edited by Borodog, 11 April 2021 - 10:25 PM.


#4 descott12

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Posted 11 April 2021 - 10:49 PM

The dedicated H-alpha scopes use very complex filter/etalons to only pass a VERY narrow bandwidth around the Ha wavelength. These are entirely different than the nighttime DSO filters.  I am not sure if this filter would help with white light or not. There are many experts on this sub-forum that could answer that. I do use a 610 longpass when doing white light, however and think that helps.


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#5 Borodog

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Posted 11 April 2021 - 10:56 PM

Thank you very much.

#6 bobzeq25

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Posted 11 April 2021 - 11:04 PM

What can be done.  I did this with pretty modest equipment (and a fair amount of experience in both data acquisition and processing).  100mm refractor (a good one, a Stellarvue), Nikon D5500 (a color camera, but the image is black and white), inexpensive Baader solar filter.

 

The following requires caps.  USING THAT IR FILTER WOULD BE VERY DANGEROUS.  Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

A DSO Ha filter is of NO USE WHATSOEVER.  That's with a solar filter.  Without one USING THAT DSO Ha FILTER WOULD BE VERY DANGEROUS.  Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

This is the world's worst place to make a mistake.  There are blind people who made one.

 

ISO 200, by the way.  <smile>  (Inside joke)

 

sun3.jpg


Edited by bobzeq25, 11 April 2021 - 11:41 PM.

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#7 bobzeq25

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Posted 11 April 2021 - 11:16 PM

And here are some prominences with the same setup, but no filter (the above was a rehearsal).  You'll need the right circumstances, they'll be here on April 8, 2024, for maybe 4 minutes in a very limited number of places.  <grin>

 

They're left and right of top center, the Bailey's Beads on the right are just sunlight shining through lunar valleys.

 

Bailey's Beads 2017.jpg


Edited by bobzeq25, 11 April 2021 - 11:28 PM.

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#8 hopskipson

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Posted 12 April 2021 - 06:23 AM

You have gotten some sound advice above.  Don't ever expose your Mak or for that matter any mirror based optic to the sun without the proper solar filter on the objective.  This is a very dangerous proposition.  If your seeing is decent you should be able to resolve convection cells with the 90mm scope.  Some filters like a continuum or a green filter will increase contrast on any surface details.  A red or Ha ccd filter can help with calming the seeing by isolating longer wavelengths of light that are less affected by bad seeing.  You already have most of the skills to produce decent images.  Search ImPPG.  It's a software that helps bring out more detail on solar images. Have fun, the sun will start to pick up in activity over the next few years.


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#9 Borodog

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Posted 12 April 2021 - 09:05 AM

Thank you. This is why you ask the questions.

 

Bob, I have seen no trace of the surface grain structure in your first image. I take it that seeing must be good? While imagine, do you see that structure on screen, or does it only become apparent with processing? What was the seeing like during the capture, how many frames did you shoot, what percentage did you stack, and what was your processing chain like, generally speaking?

 

Thanks again.



#10 bobzeq25

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Posted 12 April 2021 - 10:00 AM

Thank you. This is why you ask the questions.

 

Bob, I have seen no trace of the surface grain structure in your first image. I take it that seeing must be good? While imagine, do you see that structure on screen, or does it only become apparent with processing? What was the seeing like during the capture, how many frames did you shoot, what percentage did you stack, and what was your processing chain like, generally speaking?

 

Thanks again.

I think seeing was fine, probably better than my average.  I was thrilled to have gotten as much structure as I did with only an inexpensive solar filter.  Quite possibly someone could do more.  Maybe you.  <smile>

 

Both those pictures were simple snapshots.  Stacking frames would probably improve them.  Neither looked that good fresh from the camera.  I processed them in PixInsight, because that's what I use for DSOs, and it's more capable than anything else.


Edited by bobzeq25, 12 April 2021 - 10:02 AM.

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#11 DrummerDreamer

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Posted 13 April 2021 - 11:28 AM

Hello All, 

 

I have a quick question. I recently have bought a Seymour Helios Solar Glass filter. Would a DSO narrowband Ha filter (12nm) be completely useless to observe flares/prominences? I realize 12nm is more than two hundred times wider than some professional solar Ha filters allow so pure numbers suggest that it would be, but I was wondering if anyone had any experience (trial&error) on this topic. 

 

I am asking because I am quite excited to try my solar filter however the weather was not kind to us here in Berlin for at least 3 weeks now since I bought the filter and doesn't look promising for at least another week. 

 

Many thanks.


Edited by DrummerDreamer, 13 April 2021 - 11:42 AM.


#12 Great Attractor

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Posted 13 April 2021 - 12:14 PM

While imagine, do you see that structure on screen, or does it only become apparent with processing?

In good seeing, granulation is very apparent in the live video. In worse conditions it may show up for a few seconds from time to time ("sudden clarity"), which can often be enough for stacking software. In a really bad seeing you just see a blurry mush, stacking won't help then.


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#13 Borodog

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Posted 13 April 2021 - 02:06 PM

Thank you both.


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#14 bobzeq25

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Posted 13 April 2021 - 02:14 PM

Hello All, 

 

I have a quick question. I recently have bought a Seymour Helios Solar Glass filter. Would a DSO narrowband Ha filter (12nm) be completely useless to observe flares/prominences? I realize 12nm is more than two hundred times wider than some professional solar Ha filters allow so pure numbers suggest that it would be, but I was wondering if anyone had any experience (trial&error) on this topic. 

 

I am asking because I am quite excited to try my solar filter however the weather was not kind to us here in Berlin for at least 3 weeks now since I bought the filter and doesn't look promising for at least another week. 

 

Many thanks.

Read post #6.  Read it very carefully.  <smile>  Trial and error could easily be a life changing mistake. 

 

Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

This is the world's worst place to make a mistake.  There are blind people who made one.

 


Edited by bobzeq25, 13 April 2021 - 02:16 PM.

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#15 DrummerDreamer

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Posted 13 April 2021 - 03:06 PM

Read post #6.  Read it very carefully.  <smile>  Trial and error could easily be a life changing mistake. 

 

Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

This is the world's worst place to make a mistake.  There are blind people who made one.

Many thanks bobzeq25. I have read the entire thread before posting and while I do appreciate the urge for caution, reading your response, I am not sure if I have made myself clear. My question has nothing to do with getting creative at all.

I am new to the hobby of astrophotography however I am not new to using telescopes. The trial/error was not about breach of safety, but rather about whether the use of an additional Ha filter would be of value or not. Poor choice of words I have to admit. smile.gif

 

So rest assured, there is a solar filter (an established and standard one smile.gif ) in front of my optical train therefore there isn't any danger whatsoever. (https://www.seymours...r_Filter.html#/)

 

What I was asking about is, whether using a DSO Ha filter along would make sense and if the narrow band (12nm) is narrow enough to acquire some level of detail of the flares/prominences? Or 12nm is too wide to acquire any contrast/detail at all and is useless.  


Edited by DrummerDreamer, 13 April 2021 - 03:22 PM.


#16 bobzeq25

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Posted 13 April 2021 - 06:01 PM

Many thanks bobzeq25. I have read the entire thread before posting and while I do appreciate the urge for caution, reading your response, I am not sure if I have made myself clear. My question has nothing to do with getting creative at all.

I am new to the hobby of astrophotography however I am not new to using telescopes. The trial/error was not about breach of safety, but rather about whether the use of an additional Ha filter would be of value or not. Poor choice of words I have to admit. smile.gif

 

So rest assured, there is a solar filter (an established and standard one smile.gif ) in front of my optical train therefore there isn't any danger whatsoever. (https://www.seymours...r_Filter.html#/)

 

What I was asking about is, whether using a DSO Ha filter along would make sense and if the narrow band (12nm) is narrow enough to acquire some level of detail of the flares/prominences? Or 12nm is too wide to acquire any contrast/detail at all and is useless.  

Again, from post #6.  Note the second sentence, which anticipates your question in #15.

 

A DSO Ha filter is of NO USE WHATSOEVER.  That's with a solar filter.  Without one USING THAT DSO Ha FILTER WOULD BE VERY DANGEROUS.  Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

There are two good ways to observe/image the Sun.

 

With a white light solar filter.

 

With a dedicated solar telescope.

 

That's it.

 

In astronomy people all too often seem to want to make stuff carefully designed by serious professionals for one thing do something else.  It's rarely a good idea.  That's in DSO work.  Using an Ha filter with a one shot color camera is not really a good idea.  But that's just a matter of efficiency.

 

In solar work, using equipment that is not designed for solar work is VERY DANGEROUS.

 

H alpha from an emission nebulae (which is mostly what a DSO Ha filter is designed for), and H alpha from the Sun are completely different things, because of the context.  The Sun is not a nebulae, even though it's mostly a mass of hydrogen gas.


Edited by bobzeq25, 13 April 2021 - 06:08 PM.

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#17 DrummerDreamer

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Posted 13 April 2021 - 06:41 PM

Again, from post #6.  Note the second sentence, which anticipates your question in #15.

 

A DSO Ha filter is of NO USE WHATSOEVER.  That's with a solar filter.  Without one USING THAT DSO Ha FILTER WOULD BE VERY DANGEROUS.  Do not get creative in observing/imaging the Sun, your eyesight and camera are at stake.  Use only well established standard equipment, specifically listed as being for Solar astronomy.  CAREFULLY.

 

There are two good ways to observe/image the Sun.

 

With a white light solar filter.

 

With a dedicated solar telescope.

 

That's it.

 

In astronomy people all too often seem to want to make stuff carefully designed by serious professionals for one thing do something else.  It's rarely a good idea.  That's in DSO work.  Using an Ha filter with a one shot color camera is not really a good idea.  But that's just a matter of efficiency.

 

In solar work, using equipment that is not designed for solar work is VERY DANGEROUS.

 

H alpha from an emission nebulae (which is mostly what a DSO Ha filter is designed for), and H alpha from the Sun are completely different things, because of the context.  The Sun is not a nebulae, even though it's mostly a mass of hydrogen gas.

Many thanks. Appreciate your response. I will stick with my "boring" white light solar filter then for some daytime fun (sunspots, granularity). :) At least for now as I am not sure if I should invest on a dedicated solar Ha or double stack etalon or a dedicated solar telescope etc. as they are quite expensive.


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#18 Borodog

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Posted 13 April 2021 - 08:24 PM

Bob,

 

Are you sure the "granularity" in your image is not simply deconvolution artifact?



#19 bobzeq25

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Posted 13 April 2021 - 09:51 PM

Bob,

 

Are you sure the "granularity" in your image is not simply deconvolution artifact?

Deconvolution?  What's deconvolution?  <grin>

 

It's real.  Just a snapshot with some contrast work.  And _very_ careful focus.   Probably got lucky on seeing.

 

I appreciate the compliment.


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#20 chemman

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Posted 13 April 2021 - 10:19 PM

Many thanks. Appreciate your response. I will stick with my "boring" white light solar filter then for some daytime fun (sunspots, granularity). smile.gif At least for now as I am not sure if I should invest on a dedicated solar Ha or double stack etalon or a dedicated solar telescope etc. as they are quite expensive.

So I would think that once the light from the sun has been reduced greatly by the "boring" white light solar filter, adding an additional 12nm H-alpha filter to the light path will remove additional photons from the image rendering it even more boring.  But I don't see how it could in any way make boring more dangerous so...  if it were me I would give it a shot.  

 

Chuck


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#21 descott12

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Posted 13 April 2021 - 10:44 PM

Actually, when I said the sun was "boring" in white light, I actually meant to qualify that with "right now". I really enjoy white light viewing and imaging...there just isn't a whole lot going on right at the moment.


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#22 bobzeq25

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Posted 14 April 2021 - 12:46 AM

So I would think that once the light from the sun has been reduced greatly by the "boring" white light solar filter, adding an additional 12nm H-alpha filter to the light path will remove additional photons from the image rendering it even more boring. 

Bingo.

 

What makes it dangerous is that the beginner, seeing how bad it is, will be tempted to try and fix the problem by removing the white light solar filter.  While thinking "why not give it a shot?".

 

The DSO Ha filter is worse than useless on the Sun.  The Sun is nothing at all like an emission nebulae.
 


Edited by bobzeq25, 14 April 2021 - 12:47 AM.



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