Calcium Grains in a Tropical Winter

[yltansg]

15Jan21.

The tropical winter brought in thick clouds and rain every day. We saw the Sun for the first time in more than 2 weeks. I did some equipment maintenance and took some CAK images with the C11 fitted with ARIES D-ERF (at full aperture) + Chroma CAK filters fitted in a Skybender. Camera was an ASI174MM.



I was satisfied to have a decent CAK images with thin clouds throughout the session:



Here is a cropped version:



Please do a right-click and click on the "+" magnifier to see the images in full resolution.

Hoping to have better weather when the new active region comes into view next week.

Take care.

Alfred

[eroel]

Alfred, very nice CaK images.
My sky looks like yours.
Best regards,
Eric.

[DeepSolar64]

Very nice. You can see those calcium " supergrains " quite well.

[Carbon60]

Very nice, Alfred. Beautiful ‘fluffy’ texture in these hi-res images, even in poor conditions.

Stu.

[marktownley]

Good views Alfred. Are these at prime focus with the scope?

[yltansg]

Good views Alfred. Are these at prime focus with the scope?

Hi Mark,

Thanks for asking. Previously I used to have a Televue X2.5 PM before the Skybender with the Chroma filters and I used a 10" mask on the D-ERF. For this session, I replaced the PM with a Calcium corrector from Apollo and the imaging was done with the D-ERF at full aperture. I must check out the image scale.

Alfred

[marktownley]

Good views Alfred. Are these at prime focus with the scope?

Thanks for asking. Previously I used to have a Televue X2.5 PM before the Skybender with the Chroma filters and I used a 10" mask on the D-ERF. For this session, I replaced the PM with a Calcium corrector from Apollo and the imaging was done with the D-ERF at full aperture. I must check out the image scale.

Thank Alfred. If you have a camera with ~4.4um pixels then you will get ideal sampling with the setup when the seeing allows.

Mark

[EGRAY_OBSERVATORY]

Nice images Alfred and thanks vm

Terry

[MapleRidge]

Very sharp Calcium images Alfred...well done

Brian

[yltansg]

Thanks Eric, James, Stuart, Mark, Terry and Brian for your kind words.

I must say that I was quite surprised to get this next image under a thin cloud cover:

Full image (1930 x 1200):


Cropped 1:


Cropped 2:


Please do a right click followed by clicking "+" to see the grains in its full resolution.

Alfred

[marktownley]

Brilliant! almost reminds me of a foam.

[Montana]

Oh Alfred! I would die of happiness if I could achieve images like this

The Hubby has a made a lovely little jacket out of black-out material for my C11 over the past 2 weekends, it is great. I have also made a Tribahtinov mask to try and accurately collimate it when the weather gets a bit warmer. Then I have my fingers crossed to compete with you

Alexandra

[yltansg]

Brilliant! almost reminds me of a foam.

Hi Mark,

Some of my friends are asking why I am spending time taking pictures of something as boring as these

Alfred

[yltansg]

Oh Alfred! I would die of happiness if I could achieve images like this

The Hubby has a made a lovely little jacket out of black-out material for my C11 over the past 2 weekends, it is great. I have also made a Tribahtinov mask to try and accurately collimate it when the weather gets a bit warmer. Then I have my fingers crossed to compete with you

Alexandra

Hi Alexandra,

My C11 is out of collimation. Strange enough, it is still "ok" for solar imaging. So I am not tinkering with it. I look forward to see the lovely jacket on your SCT and do share its effectiveness with us. Tube current is one of the major concerns and most of my better images are taken before 9:30am.

So far I am driven by sharing new knowledge with my students and also the joy of learning new things. Competition is something totally new to me, haha. Sounds interesting.

At the same, lets continue our trial and experimentation and share learning points with this wonderful community to spur each other on.....


Alfred

[marktownley]

Tube current is one of the major concerns and most of my better images are taken before 9:30am.

I use a cooling fan on the HaT https://www.deepspaceproducts.com/produ ... stron-scts

P1000647 by Mark Townley, on Flickr

[LTHB]

Hi Alfred,

good to see that you are consistently getting very good results, even under a thin cloud cover!

My experience so far has been that CaK videos taken under thin clouds or even just a little haze do not result in usable images, i.e. after stacking with AS all structure is lost. With my setup slight haze or clouds seems to affect contrast in CaK much more than in h-alpha, so I am following your experiments with keen interest!

As for tube currents I am also using the cooling fans Mark recommended. They are working quite well, however they did not solve the problem entirely for my setup. I suspect that air currents in or in front of the filter stack may play a role here, as I have found that the CaK filters are heating up to well above 40°C within a minute or so (even behind an ERF and a CCD blue filter). I have added a cooling fan for the filters to my setup and will see if this helps (if the weather over here allows, which probably means in March or April).

Kind regards,

Frank

[marktownley]

Interesting to know this Frank. Thanks.

[yltansg]

Tube current is one of the major concerns and most of my better images are taken before 9:30am.

I use a cooling fan on the HaT https://www.deepspaceproducts.com/produ ... stron-scts

Thanks Mark. Unfortunately they don't have a solution for the C11 that I own. So I will have to improve the heat shield on the C11. Will check with Alexandra when she gets a chance to use it.

Alfred

[Montana]

Alfred, for solar work I think you have to be absolutely exact in collimation, this is what Christian V told me. Here are some links to my project for you to read:

I have used the new improved design as a mask.

https://github.com/cytan299/tribahtinov ... Telescopes

https://www.cloudynights.com/topic/5364 ... -focusing/

https://github.com/cytan299/tribahtinov

Original generator
https://satakagi.github.io/tribahtinovW ... tinov.html

newer generator (improved)
https://satakagi.github.io/tribahtinovW ... etric.html

To print I had to create a PDF in this program first
https://inkscape.org/

Here is a fashion show of the Hubby's fine work using blackout material. I use it to cover me while imaging and it is absolutely cold underneath, amazing stuff!

Getting ready for Spring by Alexandra Hart, on Flickr

Getting ready for Spring by Alexandra Hart, on Flickr

Getting ready for Spring by Alexandra Hart, on Flickr

Alexandra

[yltansg]

Hi Alfred,

My experience so far has been that CaK videos taken under thin clouds or even just a little haze do not result in usable images, i.e. after stacking with AS all structure is lost. With my setup slight haze or clouds seems to affect contrast in CaK much more than in h-alpha, so I am following your experiments with keen interest!

As for tube currents I am also using the cooling fans Mark recommended. They are working quite well, however they did not solve the problem entirely for my setup. I suspect that air currents in or in front of the filter stack may play a role here, as I have found that the CaK filters are heating up to well above 40°C within a minute or so (even behind an ERF and a CCD blue filter). I have added a cooling fan for the filters to my setup and will see if this helps (if the weather over here allows, which probably means in March or April).

Kind regards,

Frank

Hi Frank,

I used to have the same problem (i.e. unusable video taken in thin cloud condition) when I was using the PST filter with the Lunt CAK wedge. That is no longer a problem with the Chroma calcium filters. This is important for me because we have tons of clouds from Sep to Feb each year.

Regarding the effect of thin clouds on HA and CAK imaging, for this imaging session on 15 Jan 21, the HA video did not turn out as well as the CAK ones. Taken on the same morning, about 10 minutes after the CAK session, without any significant deterioration in cloud condition, the HA video generally looked like this:



It was taken with a very good Quark Chromosphere which has been producing excellent HA images. I need to do more HA/CAK to have a better understanding on the effect of thin clouds on the imaging.

Thanks for the info on the cooling fans. Unfortunately, my C11 is a CF (XLT) version and DSP does not carry cooling fans for it. I think the CF tube helps to some extent. Currently I have a thin aluminium foil and I can certainly improve upon it.

I use an ARIES D-ERF, which I think is extremely good at blocking out heat. Previously I made some temperature measurement for a member of this forum and the data looked good. Unfortunately I had them filed some where. So I think, I am spared the heat problem at the CAK filter.

Best regards,

Alfred

[yltansg]

Alfred, for solar work I think you have to be absolutely exact in collimation, this is what Christian V told me. Here are some links to my project for you to read:

I have used the new improved design as a mask.

Here is a fashion show of the Hubby's fine work using blackout material. I use it to cover me while imaging and it is absolutely cold underneath, amazing stuff!

Alexandra

Thanks a million for the info, Alexandra. That is a very nice looking jacket. I must made that mask and jacket!! Is there an online shop that sell the blackout material?

Alfred

[marktownley]

Alfred, Alexandra. How do you find the focus on your C11s?

I'm going to try collimating, focusing, putting a proper focuser on the back, refocusing and then imaging. I hate the native SCT focus I have to say.

Mark

[Montana]

I don't actually mind it Mark, I find it quite sensitive (the seeing is another matter)

Alfred, the blackout material was bought from a material shop and I bought 2m of it. I bought it from John Lewis department store but I guess that doesn't help you

Alexandra

[LTHB]

Hi Alfred,

I'm also using an ARIES D-ERF plus a blue CCD filter, otherwise the following filters would probably heat up a lot more, still these filters are getting about 15°C or so warmer than the surrounding air within a minute or two after pointing the scope to the sun, and I suspect that this might be enough of a temperature difference to cause some turbulences that might affect my high res videos. Anyway, that is my working hypothesis for my next CaK experiments.

Your Chroma CaK filter really seems a big step forward! It's a pity that these ultra-narrowband filters are not widely available!

Frank

[yltansg]

Alfred, Alexandra. How do you find the focus on your C11s?

I'm going to try collimating, focusing, putting a proper focuser on the back, refocusing and then imaging. I hate the native SCT focus I have to say.

Mark

Hi Mark,

I have starlight micro focuser on my C11. I do my focusing manually and has been able to good focus on it. By now, I have the hang of it and, if the seeing is not too bad. Focusing can be done within 10-15 seconds. I usually do my focusing at 100% view and then pump it to 200% to confirm it. I have uploaded 10 frame video (SER files) on Google Drive for your reference.

https://drive.google.com/file/d/1-PBDq_ ... sp=sharing

You can see why focusing on my C11 is not too difficult. I am also of the view that the native focuser cannot make it. Having a good focuser is important.

Cheers.

Alfred

[DeepSolar64]

Tube current is one of the major concerns and most of my better images are taken before 9:30am.

I use a cooling fan on the HaT https://www.deepspaceproducts.com/produ ... stron-scts

P1000647 by Mark Townley, on Flickr

And you have a Coronado finder on it!!

[yltansg]

Good views Alfred. Are these at prime focus with the scope?


Thank Alfred. If you have a camera with ~4.4um pixels then you will get ideal sampling with the setup when the seeing allows.

Mark

Hi Mark,

I do have a Basler_acA640-750um (4.8 um pixel), unfortunately it has a 640 px x 480 px. I will start with it and hope to see the difference compared with the 5.86um of the Basler acA1920-40um.

Thanks.

Alfred

[marios i.]

Very nice images!

[marktownley]

I don't think you will go wrong with that Basler 640 camera Alfred, sage advice from justapictureposter.

[yltansg]

Alfred: my best capture ever was made with that same camera. The 700 frames per second makes up for the small image size. When you record using this fast frame rate, record a 10,000 frame sample. Set the gamma level in firecapture to 64, so that the solar surface appears dark.

It will seem very dark on screen in real time, but the captured data is still there.

You can 2x drizzle the video file during stacking, and this will double the file dimensions.

The most important thing right now is proper placement of the corrector, and your firecapture settings. I set my gamma level to 60 on these to make the surface dark in real time; unless you are trying to capture spicules or prominences on the limb you should be doing the same.

The wide view is from the basler 1920-155um , the narrow view is from the 720.

Thank you for the tips on the placement of the corrector and the firecapture settings, Justapictureposter!!

You picture is fantastic!! I have delayed using the camera because of the different experiments and weather. This camera is going onto the jig and hopefully the weather will cooperate to get some images on AR2797.

Alfred

[yltansg]

I don't think you will go wrong with that Basler 640 camera Alfred, sage advice from justapictureposter.

Hi Mark,

I am assured Today was a total washout. I hope to post pictures on the new sunspot soon.

Alfred

[DavidP]

Justapicture. Those a beautiful dramatic images. Can you say anything more about your use of gamma?

[DeepSolar64]

Very nice animations!!

[marktownley]

Great anis! Both gamma settings have their own merit!

[MapleRidge]

Superb mages and animation in the latest addition of CaK

I appreciate the processing and capture info as well!

Brian