New Spectroheliograph construction (based on 102mm refractor)

[SunRick]

Here are a couple spectroheliograms from today (h-alpha and calcium-H). The h-alpha was 102mm f/7 and the calcium was stopped down to 72mm. This is the first day in a week that the sun has been out in the morning! You can see new sunspot 3697 just emerging on the left limb....and that was the infamous sunspot 3664 a few weeks ago that caused the nearly worldwide auroras. It survived its 2-week trip across the back side of the sun. Will we have an aurora repeat in the next week or two? We shall see!

Rick

102mm f/7 SHG (5/28/24)

Sun 5-28-24 new SHG h-alpha.jpg (2.33 MiB) Viewed 4696 times

102mm f/7 SHG stopped to 72mm (5/28/24)

Sun 5-28-24 new SHG calcium-H.jpg (2.41 MiB) Viewed 4696 times

[SunRick]

There was some very good daytime seeing at 9:00 AM this morning local time. So, of course, I had to set my mount up and partake in some spectroheliographic activities! The SHG system just keeps chugging along (cross my fingers nothing goes wrong). Once again, h-alpha at 102mm and calcium-H stopped down to 72mm. I'm still able to use a transversallium correction setting of just 1.0.

I am still amazed at how contrasty the calcium image is. The sunspot areas are very bright, and the other areas are pretty dark. I have to significantly bring up the midpoint on the curves function in IMPPG software so the non-spot areas are no so dark. If I expose with a higher gain to get a brighter background, then I blast out some brighter spot features. It's a balancing act.

Rick

SHG h-alpha 102mm 5/30/2024

Sun 5-30-24 new SHG h-alpha.jpg (2.44 MiB) Viewed 4659 times

SHG calcium-H stopped to 72mm 5/30/2024

Sun 5-30-24 new SHG calcium-H.jpg (2.44 MiB) Viewed 4659 times

[Montana]

I do love seeing the magnificent CaH filaments

Alexandra

[Albireo]

Hi Rick,

Sorry I totally forgot to reply to you
Thanks for your detailed response!

With my Sol'Ex, I also used an 80mm f/5 Orion scope, but stopped it down to 70mm.

The images you can get with the Sol'Ex may satisfy you. They are not bad at all (see one of my Sol'Ex images earlier in this thread).

Cool that you used an equivalent scope, your Sol'Ex images don’t look bad at all! I’d be happy to start with similar results

You will need an extension tube between your scope and Sol'Ex.....so just thread a neutral density filter on the extension tube where the sun is not focused.

Do you mean the 1.25“ nosepiece or an additional extension tube? And which strength of ND filter would you recommend?

Of course, I must say there is a great deal of satisfaction in building a high resolution SHG from scratch.....that actually reliably works the way it is supposed to. It is really cool!

I totally see myself eventually doing that (I even thought about one day building a coronograph but that’s an order of magnitude more complicated and can absolutely wait ). For the beginning I‘m absolutely happy starting out with the Sol'Ex!

I already ordered the parts from AzurPrint and am now compiling what else I need (apart from the optical elements) For now I have in my basket a nosepiece, L1 filter for energy rejection, a helical focuser, a solar continuum filter for eventual corona observation tests. An ND filter plus maybe an extension tube would be added as well. Am I missing something essential?

Thanks for your help!
Jan

[SunRick]

Hi Jan,

I already ordered the parts from AzurPrint and am now compiling what else I need (apart from the optical elements) For now I have in my basket a nosepiece, L1 filter for energy rejection, a helical focuser, a solar continuum filter for eventual corona observation tests. An ND filter plus maybe an extension tube would be added as well. Am I missing something essential?

Yes, you need a nosepiece to screw onto the threads of the Sol'Ex, a ZWO helical focuser that also screws on to the Sol'Ex, an ND filter to protect the slit from intense focused sun, and probably an extension tube to reach focus (since you will not be using a diagonal). You don't need an L1 filter for the Sol'Ex. The L1 filter is used on my homemade SHG (in place of the ND filter you use on the Sol'Ex).

The ND filter I used is a Baader ND 0.9. This is a 12.5% transmission filter. Screw it on the end of your extension tube. This is enough distance before the focal point so the solar image is still unfocused quite a bit.

The other thing you did not list is a camera. Use the ZWO ASI178mm camera.

Rick

[Albireo]

Hi Jan,

Yes, you need a nosepiece to screw onto the threads of the Sol'Ex, a ZWO helical focuser that also screws on to the Sol'Ex, an ND filter to protect the slit from intense focused sun, and probably an extension tube to reach focus (since you will not be using a diagonal). You don't need an L1 filter for the Sol'Ex. The L1 filter is used on my homemade SHG (in place of the ND filter you use on the Sol'Ex).

The ND filter I used is a Baader ND 0.9. This is a 12.5% transmission filter. Screw it on the end of your extension tube. This is enough distance before the focal point so the solar image is still unfocused quite a bit.

The other thing you did not list is a camera. Use the ZWO ASI178mm camera.

Rick

Thanks!
Okay I see, then I will not get the L1 filter. The Baader 0.9 was actually the one I initially thought about getting but I thought before buying just some filter I’d ask. But great that it is indeed a good choice.

Sorry I didn’t mention the camera as it’s still my ASI174MM.
I‘ll probably get the 178MM rather soonish as well, just to get that better spectral and spatial resolution but for starting out I would just use my 174MM and save some money for now.

Edit:
I just out of curiosity looked up the 178MM and it seems it’s discontinued with the 678MM being the successor. It does have even smaller pixels (2μm) but can only record in 12 bit (and at a slightly lower frame rate but I guess that’s not much of a problem, since the ROI is so small anyway).
Would the lower bit depth be a big problem with the Sol'Ex / any SHG? To get a 178MM I would have to keep an eye on e.g. eBay, my GoTo (pun intended) shops don’t seem to sell it anymore.

[SunRick]

If you already have the ASI174mm (which I also have in addition to the 178mm and the 183mm), just use it. The pixels may be a little large, but that's OK. You will still get a good image. I use my 174mm for imaging the sun at 5,100mm focal length. I use my 178mm with the Sol'Ex. And I use the 183mm with my 102mm f/7 homemade SHG. The 183mm has the same pixels as the 178mm.....just a lot more of them!

Doug, maybe you could comment more about the "ideal" camera for a Sol'Ex.....since the ASI178mm is no longer made.

Rick

[thesmiths]

Doug, maybe you could comment more about the "ideal" camera for a Sol'Ex... since the ASI178mm is no longer made.

The real ideal camera for the standard Solex is the ASI 533MM camera. This is because the pixel size of the IMX 178 is actually too small for bin 1x1 and too large in bin 2x2. The 533MM is actually a very good all-round solar camera (the square sensor is quite suitable for solar and lunar).

You can still get the IMX 178 from other camera makers like Player One (e.g. the Neptune-M).

[Albireo]

Thanks Rick and Doug!

I will just use my 174MM and try to get the best out of it.
If I find that I want to use a different camera I will see what I can get then

[SunRick]

Here is a 102mm f/7 spectroheliogram of the sun today. It featured several active regions and a long filament. Yay, solar maximum! For best viewing, use a large monitor with the image at full resolution....and pan around to see all the cool features today!

SHG h-alpha 6/4/2024

Sun 6-4-24 new SHG h-alpha.jpg (2.43 MiB) Viewed 4493 times

Rick

[SunRick]

The sun is still quite active today, and the SHG showed it (h-alpha/calcium-H)! Large spot 3697 (which caused the May 10th/11th worldwide auroras) is about to exit the sun's limb a second time. Will it survive the backside trip again? A large filaprom is near it now, and makes a pretty target. I've got the SHG rotation and framerate pretty dialed in now, with a Y/X ratio of 0.991 and an unrotation angle of 0.14 degrees.
The routine of switching from h-alpha to calcium-H (placing the 72mm stop on the scope lens, rotating the grating, refocusing the imaging lens, refocusing the scope, and setting the correct gain) takes me just 2 to 3 minutes to do it all so I am ready to start recording calcium scans. I love this SHG more every time I use it.

Rick

SHG h-alpha 6/7/2024

Sun 6-7-24 new SHG h-alpha.jpg (2.44 MiB) Viewed 4423 times

SHG calcium-H 6/7/2024

Sun 6-7-24 new SHG calcium-H.jpg (2.37 MiB) Viewed 4423 times

[SunRick]

I should not post images so often on my spectroheliograph construction and operation thread.....but I can't resist when the seeing is very good! I really will start picking and choosing and posting images less often. I don't want to get boring and repetitive, as the point has been made that this SHG setup works OK for me so far.
One question I have.....does anyone know if blueshifting or redshifting off the calcium-H centerline via pixel shifting shows anything interesting (like it does for h-alpha)? If no one knows.....I can try it and report back.

Rick

SHG h-alpha 6/11/2024 (102mm)

Sun 6-11-24 new SHG h-alpha.jpg (2.37 MiB) Viewed 4324 times

SHG Calcium-H 6/11/2024 (stopped to 72mm)

Sun 6-11-24 new SHG calcium-H.jpg (2.52 MiB) Viewed 4324 times

[rsfoto]

Impressive images

[Montana]

These are just superb!! I love to drool over these images. Please do try a red/blue shift, I have seen with halpha but not sure about Calcium. I know that Douglas has shown individual images through the line which is very interesting.
viewtopic.php?t=37424


Alexandra

[SunRick]

These are just superb!! I love to drool over these images. Please do try a red/blue shift, I have seen with halpha but not sure about Calcium. I know that Douglas has shown individual images through the line which is very interesting.
viewtopic.php?t=37424


Alexandra

Hi Montana,
Hah! I should have known Doug would have explored this already! Thanks for the link you included in your post that shows Doug's gradual red and blue shift of a calcium-H image via the pixel shift feature in his software.

Rick

[SunRick]

Thanks Alexandra and Rainer,

OK. Here is an h-alpha SHG image from today under very good seeing again.

Rick

SHG 6/12/2024 h-alpha

Sun 6-12-24 new SHG h-alpha.jpg (2.28 MiB) Viewed 4264 times

[rsfoto]

Absolutely stunning image

[SunRick]

Well......this morning was the best seeing day I have had this year for solar SHG imaging. It was warm, calm, and very transparent (no Canadian/western American wildfires yet this year). And, the jet stream winds were in the 0 - 20 knot range. The lawn and lush farm field the scope looks over still had dew. It was just ideal. The sun had a lot activity too. I hope this is reflective of the many days I will have this summer with similar conditions and peak solar activity.

I attached an h-alpha image and a calcium-H image. You can see lots of fine detail on the full-res calcium image that isn't there in anything less than very good seeing. Also, there seems to be a long, vertical calcium filament that only segments of show up in the h-alpha image. Maybe it's an optical illusion. Or, maybe calcium filaments show differently.

h-alpha at full 102mm f/7. Calcium-H stopped down to 72mm.

Rick

Sun SHG h-alpha 6/13/2024

Sun 6-13-24 new SHG h-alpha.jpg (2.39 MiB) Viewed 4212 times

Sun SHG calcium-H 6/13/2024

Sun 6-13-24 new SHG calcium-H.jpg (2.38 MiB) Viewed 4212 times

Jet stream when imaging (pink "X" is my location)

Jet Stream 6-13-24.jpg (586.68 KiB) Viewed 4212 times

[Montana]

Simply stunning

Alexandra

[Ivan]

Rick, your images are phenomenal! I also want to build a SHG, could you tell me more about how to fix the gap.

an

[SunRick]

I'm only trying to post images when the seeing is super good. Well, this morning was the best yet this year.....even better than a few days ago. An upper level high pressure ridge is parking over my town this week, which should give good seeing (and 95 degree F temperatures with very high humidity!). If today is any preview, I can't wait!
The sun was really ripping today.....with an electric sunspot complex, some other good sunspots, a large prominence, and a large filament. What more could you ask for? Don't you love solar max? The SHG keeps chugging along. Doug Smith guided my construction every step of the way....and it's a pleasure to use.
I attached an h-alpha image and a calcium-H image. Bring them up at full-resolution on a large monitor and pan around (right-click/open image in new window/click + magnifier). Once again, I stopped down the calcium image to 72mm.

Rick

102mm f/7 SHG h-alpha 6/16/2024

Sun 6-16-24 new SHG h-alpha.jpg (2.36 MiB) Viewed 4135 times

102mm f/7 SHG calcium-H 6/16/2024

Sun 6-16-24 new SHG calcium-H.jpg (2.25 MiB) Viewed 4135 times

[SunRick]

Rick, your images are phenomenal! I also want to build a SHG, could you tell me more about how to fix the gap.

an

Hi Ivan,

Thank you very much. When you say "fix the gap".....do you mean how to set the distance between the collimating lens and the diffraction grating? And, also the distance between the grating and the imaging lens?
If you replicate this SHG assembly using the same parts, the distance between the front edge of the collimating lens and the center of the diffraction grating should be about 100mm. The distance between the grating and the front edge of the imaging lens should also be about 100mm. I set the angle between the 2 camera lenses at about 30 degrees. A setup like this will make the two camera lenses nearly touch each other at their front rims. I adjusted everything so they are both the same distance from the grating. I think Doug makes his imaging lens project slightly in front of the collimating lens, but mine are the same.
If I misunderstood your question, please let me know.

Rick

[Montana]

The prominence is really super and both excellent images

Have you tried any of the more unusual lines yet?

Alexandra

[Ivan]

Thank you so much for answering Rick! Yes, that's what I was trying to clarify. And how to insert an optical slit into the filter frame? Do you need some kind of copper substrate or something similar?

Your last image... I don't have enough words to express my delight.

Ivan

[SunRick]

Thank you so much for answering Rick! Yes, that's what I was trying to clarify. And how to insert an optical slit into the filter frame? Do you need some kind of copper substrate or something similar?

Your last image... I don't have enough words to express my delight.

Ivan

Hi Ivan,

The slit I procured from Doug Smith in London was already assembled into a 1.25-inch filter cell. I believe Doug used copper backing on both sides. He can give you more detail. He had a number of slits made with chrome on quartz applied using photolithography. Mine is 12mm x 9 micron. I think the slits he currently has available are 8 microns wide. I mounted this slit assembly using a T-thread adapter ring that has 1.25-inch threads in its center. The slit assembly from Doug just screwed right in!

Rick

[SunRick]

The prominence is really super and both excellent images

Have you tried any of the more unusual lines yet?

Alexandra

Hi Alexandra,

The lines I have tried are h-alpha (plus blue and red pixel-shifting), h-beta, magnesium II, and calcium-H. I have not tried anything more exotic yet.....like h-gamma, h-delta, h-epsilon, iron, etc. Doug Smith told me that these other "h" lines basically look like h-beta. I see other nice bold spectral lines while perusing the spectrum as I am rotating the grating and looking at the computer monitor. The sodium doublet looks cool, but I think it would just give basically a white-light image. I could also image calcium-K, but Doug says it is the same as calcium-H....and the H line, being closer to the visible spectrum, should give a little better sharpness with typical APO scopes. I understand oxygen spectral lines are from the earth's atmosphere.
If you have an idea for a cool spectral line that would show some detail other than a white-light image......let me know!

Thanks.

Rick

[Rusted]

Forgive me, but in comparison with more typical commercial etalon images. Even the most costly narrow band and double/triple stacked etalons. It is often difficult to judge how well the SHG is doing on whole disk. The presentation looks slightly different. Just as it does with double etalon captures. Putting it bluntly, "whole disk" does the equipment's narrow band resolution potential no great favours. IMO.

Zooming in [by cropping] is a digital enlargement with all it potential for artifacts and loss of detail. All that said, I had a quick play with a heavily cropped part of your image. Just to see what your resolution looked like. I readily admit it was an extremely clumsy exercise. Completed in just a few seconds with a free and obsolete image handling software. I also cheated and overdosed on sharpening. Aside from my own clumsiness, I still thought the result was interesting and very probably aperture/digital enlargement limited.

So, one must ask, does your SHG need a "Barlow lens?" To bring out the fine detail hidden by the presentation scale of whole disk capture? To blow us all away. By the new detail afforded by ultra narrow band capture. Or is optical enlargement too heavy a load for the SHG to manage with present technology? Does the SHG suffer a lack of light? Is it solar tracking or scanning limited? Would a bigger, longer focus objective pay dividends?

h a crop col.jpg (178.33 KiB) Viewed 4053 times

[Montana]

I'd like to see Helium D3

Alexandra

[SunRick]

Forgive me, but in comparison with more typical commercial etalon images. Even the most costly narrow band and double/triple stacked etalons. It is often difficult to judge how well the SHG is doing on whole disk. The presentation looks slightly different. Just as it does with double etalon captures. Putting it bluntly, "whole disk" does the equipment's narrow band resolution potential no great favours. IMO.

Zooming in [by cropping] is a digital enlargement with all it potential for artifacts and loss of detail. All that said, I had a quick play with a heavily cropped part of your image. Just to see what your resolution looked like. I readily admit it was an extremely clumsy exercise. Completed in just a few seconds with a free and obsolete image handling software. I also cheated and overdosed on sharpening. Aside from my own clumsiness, I still thought the result was interesting and very probably aperture/digital enlargement limited.

So, one must ask, does your SHG need a "Barlow lens?" To bring out the fine detail hidden by the presentation scale of whole disk capture? To blow us all away. By the new detail afforded by ultra narrow band capture. Or is optical enlargement too heavy a load for the SHG to manage with present technology? Does the SHG suffer a lack of light? Is it solar tracking or scanning limited? Would a bigger, longer focus objective pay dividends?

Hi Rusted,
I will try and answer your questions as best I can. I am not an SHG expert, though. Doug Smith might be able to give better answers.

The SHG I use as constructed and designed is meant to produce a whole-disk image. I currently also image in high resolution (5,100 mm focal length) with a double stack (Quark/Lunt) etalon system based on a 127mm f/9.4 refractor. What I was missing was a whole-disk system, and this SHG design fit that bill. One of the downsides is that a lot of the fine detail goes away if the image is shrunk down to view the entire disk all at once on a monitor.....even a large, high resolution monitor. Basically, to see all the detail, you need to display the image at full resolution and then pan around. The resolution of my SHG system is 0.70 arcseconds per pixel. I am also amazed at the contrast provided by the SHG's equivalent bandpass of about 0.1 Angstroms, and the somewhat different views that provides. Calcium images especially are very unfamiliar looking due to this.

Doug Smith in England has done a lot of SHG experimenting with different scopes and collimating/imaging lens optics. He has found that scopes in the 100mm range with 700 - 800 mm focal length, combined with the Pentax Takumar 150mm f/4 lenses (made in the 1960's) and commercially available 50mm square diffraction gratings is a real sweet spot to use with mounts that can scan around 16X. My particular 27 year old mount can scan at 8X or 16X, and I have no other scan speed options.

Longer focal length scopes would produce larger sun images at the slit. My slit is 12mm long, and could certainly handle a longer focal length scope of 1,000 mm. My ASI183mm camera could also handle a larger solar image. But, the collimating optics and the diffraction grating would need to be larger to accommodate this. On my 31-inch ADM dovetail plate, everything just fits perfectly with the current design. Other than the slit, all components of my system were off-the-shelf parts.

Incorporating a barlow into my current imaging lens assembly could technically be done, providing a larger spectral line image scale for the camera. For example, a 2X barlow would give a 5,384 pixel wide image at the camera, and the camera has a 5,496 pixels wide chip. That is way too tight for full-disk, as it would provide not enough room for prominences, etc. The biggest problem is the barlowed wider and longer h-alpha spectral line would require a wider and longer ROI recording box size.....and the frame-per-second recording speed would approach 700 fps. My laptop cannot do that. I would have to drop down to 8X scanning speed.

Now, if you wish to use a barlow to record just part of the sun and not the whole disk (with a shorter ROI box), the fps recording speed would still need to be around 700 fps at 16X scanning speed. Even with a shorter ROI box (but still wider)......700 fps is just not doable. The other option would be dropping down to 8X scanning speed, and then the recording speed could drop down to around 350 fps. With my current SHG system for h-alpha, I scan at 16X and record a 3208x92 pixel ROI box at 363 fps. Even that is a heavy demand on my laptop and SSD to get zero dropped frames.

Finally, I did also image the same sunspot complex (3712) you showed on the same day with my 127mm non-SHG Quark/Lunt double-stack system described earlier. Here is that image as a comparison. Let me know if I answered your questions, or maybe Doug could elaborate better than me!

Rick

127mm double-stack sunspot 3712

Sun 6-16-24 sunspot 3712-1 s.jpg (539.82 KiB) Viewed 4015 times

[Rusted]

Thank you Rick for taking the trouble to answer.

Firstly I had no idea you were deliberately using your SHG for whole disk.
I am not very familiar with the technology, scanning and software involved so your response helped.
The images you produce with the SHG are certainly well worth your investment in time and money.

The high res image of the AR is also of very high quality.

Keep at it and thanks again.

[SunRick]

Well......the sky was clear, the air was tropical and calm....and the jet stream was way up near the Canadian border. This is just what a solar imager in Kentucky (USA) likes, as the seeing conditions this morning were very, very good! So, of course, I had to drag out the mount and put the trusty SHG on it for some imaging before the clouds formed. The triumvirate of active sunspots are rapidly approaching the solar limb.....without much activity behind them. So, that was another reason to image!
In addition, there was a nice, long filament arcing across the disk, and it showed up well.
To top it all off, these are solstice images! Happy summer solstice!!
H-alpha and calcium-H. The calcium-H image was stopped down from 102mm to 72 mm.

Rick

Sun SHG h-alpha 102mm f/7 6-20-24

Sun 6-20-24 new SHG h-alpha.jpg (2.44 MiB) Viewed 3913 times

Sun SHG calcium-H 72mm 6/20/24

Sun 6-20-24 new SHG calcium-H.jpg (2.54 MiB) Viewed 3913 times

[Montana]

Magnificent!! Happy Solstice

Alexandra

[SunRick]

Here are a couple SHG images from today (h-alpha and calcium-H). The next week does not look so good for imaging, so I thought I'd post these. Seeing was once again very good, with calm winds, and very hot/humid air mass. Today, the sun showed sunspot features on both sides, but not much activity in the middle. However, there is a nice long filament in the middle of the sun, which shows up well in both h-alpha and calcium-H.

Rick

SHG h-alpha 6/21/2024

Sun 6-21-24 new SHG h-alpha.jpg (2.5 MiB) Viewed 3857 times

SHG calcium-H 6/21/2024

Sun 6-21-24 new SHG calcium-H.jpg (2.54 MiB) Viewed 3857 times

[Ivan]

Absolutely incredible image quality! Looking at them, I no longer want to take off the FD's mosaics. Your images are an order of magnitude higher quality.

Ivan

[SunRick]

Last day of good seeing for a while (I think.....you never know!). This morning (6/22) was supposed to be cloudy, but it was clear and calm again. This year is solar max, so I am trying to image with the SHG as much as I can. There will be future years with nothing at all, and I can go back and look at this year's pics then!

Rick

SHG h-alpha 102mm 6/22/24

Sun 6-22-24 new SHG h-alpha.jpg (2.39 MiB) Viewed 3773 times

SHG Calcium-H 72mm 6/22/24

Sun 6-22-24 new SHG calcium-H.jpg (2.45 MiB) Viewed 3773 times

[SunRick]

Today, it was very clear/transparent, and there was just a very light breeze. What a difference this year compared to last year.....when there were huge western Canadian wildfires 1,000 - 2,000 miles away giving me smoky gray skies for much of the Spring/Summer!

Anyway, here are h-alpha and calcium-H images from today. There was a large filament, which showed up well on both images.

Rick

Sun 102mm f/7 SHG calcium-H 6/24/2024

Sun 6-24-24 new SHG h-alpha.jpg (2.5 MiB) Viewed 3673 times

Sun 102mm f/7 stopped to 72mm SHG calcium-H 6/24/2024

Sun 6-24-24 new SHG calcium-H.jpg (2.51 MiB) Viewed 3673 times

[Montana]

Incredible pictures, the big filament looks great in both wavelengths

Alexandra

[SunRick]

The sun was lookin' good today with the SHG! Some nice sunspots in h-alpha and lots of details in calcium-H too.
Look at full-res on a large monitor!

Rick

102mm f/7 SHG h-alpha 6/27/2024

Sun 6-27-24 new SHG h-alpha.jpg (2.31 MiB) Viewed 3515 times

102mm f/7 stopped to 72mm SHG calcium-H 6/27/24

Sun 6-27-24 new SHG calcium-H.jpg (2.48 MiB) Viewed 3515 times

[Albireo]

The sun was lookin' good today with the SHG! Some nice sunspots in h-alpha and lots of details in calcium-H too.
Look at full-res on a large monitor!

Rick

Sun 6-27-24 new SHG h-alpha.jpg

Sun 6-27-24 new SHG calcium-H.jpg

These look amazing! I love how you can even see the fibrils in calcium, absolutely gorgeous!
I actually observed both H-alpha and calcium H as well with my Sol'Ex at almost the same time and I‘m super happy with my results so far

[SunRick]

These look amazing! I love how you can even see the fibrils in calcium, absolutely gorgeous!
I actually observed both H-alpha and calcium H as well with my Sol'Ex at almost the same time and I‘m super happy with my results so far

Thanks Albireo! I also started out with a Sol'Ex and an Orion 80mm f/5 scope (stopped to 70mm). I was able to get some quite nice images. Being able to get nice images with the Sol'Ex was the encouragement I needed to build my own larger SHG. It gave me the "I think I can do this" confidence. Are you considering building a larger SHG, or are you happy with the Sol'Ex results? Plenty of folks are quite happy with Sol'Ex results!

Rick

[Albireo]

Thanks Albireo! I also started out with a Sol'Ex and an Orion 80mm f/5 scope (stopped to 70mm). I was able to get some quite nice images. Being able to get nice images with the Sol'Ex was the encouragement I needed to build my own larger SHG. It gave me the "I think I can do this" confidence. Are you considering building a larger SHG, or are you happy with the Sol'Ex results? Plenty of folks are quite happy with Sol'Ex results!

Rick

I‘m absolutely considering building my own larger SHG but at the moment I‘m lacking the telescope for it (and my Sol'Ex is brand new ).
I assembled it on Monday and have only tried it twice so far (you can check out my thread 'Sol'Ex first light' if you‘d like to see the results).
I‘m happy with the Sol'Ex results in the way that I‘m enjoying what I can do with it, but I also know what’s possible with a bigger SHG And I see much room for improvement with my results as well, e.g. stacking multiple images and really nailing the different focuses.

Maybe a question about your own Sol'Ex-perience, why exactly did you stop it to 70mm? To get good sampling or to reduce the amount of light?
For my tests I stopped it to about 30-40mm (the cap had a removable piece of that size) because I was afraid of opening up the full 80mm.

Cheers,
Jan

[SunRick]

I‘m absolutely considering building my own larger SHG but at the moment I‘m lacking the telescope for it (and my Sol'Ex is brand new ).
I assembled it on Monday and have only tried it twice so far (you can check out my thread 'Sol'Ex first light' if you‘d like to see the results).
I‘m happy with the Sol'Ex results in the way that I‘m enjoying what I can do with it, but I also know what’s possible with a bigger SHG And I see much room for improvement with my results as well, e.g. stacking multiple images and really nailing the different focuses.

Maybe a question about your own Sol'Ex-perience, why exactly did you stop it to 70mm? To get good sampling or to reduce the amount of light?
For my tests I stopped it to about 30-40mm (the cap had a removable piece of that size) because I was afraid of opening up the full 80mm.

Cheers,
Jan

Hi Jan,

While using my Sol'Ex, I stopped my 80mm f/5 scope to 70mm because at f/5, my particular scope was not really optimized for h-alpha light (and certainly not calcium). Unlike my current 102mm f/7 APO SHG scope, I could not get a razor sharp solar edge when focusing. I was a little sharper at 70mm. You should try some different aperture stops with your scope to see what is best for you. Also, you really need to stack multiple exposures (10 to 20) and sharpen. Use Autostakkert and IMPPG.....both freeware. The results will be much better. You should be able to get 4 scans per minute if you alternate N-S or E-W scanning directions.

I looked at your initial images, and the biggest problem I see is your seeing conditions when you imaged. Whenever you see the jagged edges (looks like you are scanning E-W direction), that is bad seeing. On a day of good seeing in the morning, you should not get those jagged edges and jagged filaments. Your second attempt has much less jagged edges. Calm summer mornings should be best. Is your Y/X value near 1.00 and your unroation angle less than 1 degree? Also, don't get your ND filter too close to focus. You want that sun image spread out unfocused over the filter. If you use an extension tube, put the filter on the end of it.

Rick

[SunRick]

Here is another SHG image (h-alpha only) from 6/28/24. The seeing was good again, but clouds rolled in before I could image calcium.

Rick

SHG h-alpha 102mm 6/28/2024

Sun 6-28-24 new SHG h-alpha.jpg (2.35 MiB) Viewed 3413 times

[Albireo]

Hi Rick,

thanks for your answer!

While using my Sol'Ex, I stopped my 80mm f/5 scope to 70mm because at f/5, my particular scope was not really optimized for h-alpha light (and certainly not calcium). Unlike my current 102mm f/7 APO SHG scope, I could not get a razor sharp solar edge when focusing. I was a little sharper at 70mm. You should try some different aperture stops with your scope to see what is best for you. Also, you really need to stack multiple exposures (10 to 20) and sharpen. Use Autostakkert and IMPPG.....both freeware. The results will be much better. You should be able to get 4 scans per minute if you alternate N-S or E-W scanning directions.

Ah I see. I'll try out what works best for me.
Yes, I already use Autostakkert and ImPPG with my Lunt images, I would have used it for the Sol'Ex as well, if I had enough time to make multiple scans (I was lucky to get some images without cloud streaks at all)...

I looked at your initial images, and the biggest problem I see is your seeing conditions when you imaged. Whenever you see the jagged edges (looks like you are scanning E-W direction), that is bad seeing. On a day of good seeing in the morning, you should not get those jagged edges and jagged filaments. Your second attempt has much less jagged edges. Calm summer mornings should be best. Is your Y/X value near 1.00 and your unroation angle less than 1 degree? Also, don't get your ND filter too close to focus. You want that sun image spread out unfocused over the filter. If you use an extension tube, put the filter on the end of it.

I see. For my first test, the major problem was definitely the mount. Initially I used my SolarQuest, which is an Alt/Az mount and uses a sliding pad, which worked only really poorly. The image I posted was the best by far.
For my second try I used my HEQ-5 and here I agree that probably the seeing was the limiting factor. I did actually do a N/S scan and rotated the image.
For the ND filter, I only bought one extension tube and I need it to reach focus for the spectral lines (just the camera and the helical focuser was not enough). But of course safety is the most important thing at all, so I'll buy an additional one to place the filter further away from focus.

[SunRick]

I see. For my first test, the major problem was definitely the mount. Initially I used my SolarQuest, which is an Alt/Az mount and uses a sliding pad, which worked only really poorly. The image I posted was the best by far.
For my second try I used my HEQ-5 and here I agree that probably the seeing was the limiting factor. I did actually do a N/S scan and rotated the image.
For the ND filter, I only bought one extension tube and I need it to reach focus for the spectral lines (just the camera and the helical focuser was not enough). But of course safety is the most important thing at all, so I'll buy an additional one to place the filter further away from focus.

Hi Jan,

For clarification, if you are already using one extension tube (instead of your diagonal mirror), placing the ND filter on the end of that one extension tube is OK. That is plenty far from the focus point. Don't put in on the end of the Sol'Ex 1.25-inch or 2-inch barrel. That is getting closer to the focus point. The only reason you would need a second extension tube is if you could not reach focus......or if your focuser is a bit wobbly racked all the way out.

Rick

[Albireo]

For clarification, if you are already using one extension tube (instead of your diagonal mirror), placing the ND filter on the end of that one extension tube is OK. That is plenty far from the focus point. Don't put in on the end of the Sol'Ex 1.25-inch or 2-inch barrel. That is getting closer to the focus point. The only reason you would need a second extension tube is if you could not reach focus......or if your focuser is a bit wobbly racked all the way out.

Hi Rick,

yes, unfortunately I have to use the extension tube on the nose piece of the camera to reach focus on the spectrum itself. That means I currently don't have one at the entrance of the Sol'Ex.

Jan

[SunRick]

Hi Rick,

yes, unfortunately I have to use the extension tube on the nose piece of the camera to reach focus on the spectrum itself. That means I currently don't have one at the entrance of the Sol'Ex.

Jan

Hi Jan,

I'm not sure I understand. I didn't need an extension tube on the nosepiece of my Sol'Ex camera. I see you have an ASI174mm, and I use an ASI178mm camera for my Sol'Ex. The backfocus of both cameras is virtually identical. The Sol'Ex is designed for use with a ZWO helical focuser. If you use it with the spacer ring that comes with the Sol'Ex, your ASI174mm should focus fine.
I did need an extension tube on my scope focuser (in place of the diagonal)....and still, I had to rack out my scope focuser nearly all the way. See the picture of my old Sol'Ex below. But, no extension tube on the camera (just the spacer ring).

Sol'Ex with 80mm f/5 scope

Sol'Ex spectroheliograph.jpg (447.9 KiB) Viewed 3296 times

[Albireo]

Hi Jan,

I'm not sure I understand. I didn't need an extension tube on the nosepiece of my Sol'Ex camera. I see you have an ASI174mm, and I use an ASI178mm camera for my Sol'Ex. The backfocus of both cameras is virtually identical. The Sol'Ex is designed for use with a ZWO helical focuser. If you use it with the spacer ring that comes with the Sol'Ex, your ASI174mm should focus fine.
I did need an extension tube on my scope focuser (in place of the diagonal)....and still, I had to rack out my scope focuser nearly all the way. See the picture of my old Sol'Ex below. But, no extension tube on the camera (just the spacer ring).

Sol'Ex spectroheliograph.jpg

Hi Rick,

I'm stupid... You're right!
When I assembled the Sol'Ex I tried to get my camera into focus, couldn't do it without the extension tube and tried with the T2 extension tube that Azur3D included. Only I screwed it onto the ZWO focuser and screwed the camera to it. That way I could reach focus but I didn't like having to screw my camera onto the extension tube instead of inserting it with the nose piece.
But somehow it never dawned on me that I just have to swap the focuser and the extension tube. So I set the extension tube aside and forgot about it.
Now that I've seen your picture I remembered the tube, unscrewed the focuser, placed the extension tube, screwed the focuser back on (even removed the spacer ring), tried it out and lo and behold it works! Now I put my 1.25" extension tube on the Sol'Ex nose piece and screwed the ND filter in there! I even took the opportunity to focus both lenses a little bit better, so now all should be set for the next time I have good weather and enough time

On a different note: I just noticed that when I focus the helical focuser, the camera orientation rotates ever so slightly. Overall it's not much and would still show the whole line in the ROI but I wonder if that's normal or if I can prevent this.

Thanks so much for your help!

[SunRick]

Here is another SHG image of the sun today. Not as much activity with one exiting sunspot group and one entering sunspot group. But, no spectacular filaments.

Rick

Sun 7/6/2024 SHG h-alpha

Sun 7-6-24 new SHG h-alpha 2.jpg (2.44 MiB) Viewed 3207 times

[thesmiths]

Here is another SHG image of the sun today.

Was there a little more turbulence than you normally get? It looks like the features are slightly less distinct that your typical images.