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October 10, 2021: H-alpha with the 8" Tri-Band SCT


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Little mosaic of just 4 panes using the 8" Tri-Band SCT with Baader TZ-3 tele-centric lens, Solar Spectrum 0.3 Å H-alpha filter, and ASI174 camera. Seeing got increasingly choppy, and I might have missed exact focus. I stacked 2000 frames out of 10,000, 5 ms exposure time.

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Must work harder at getting good focus. This was mainly a test of my new laptop, equipped with an Intel Core i9, 32 GB RAM, a 2 TB SSD, and nVidia RTX 3070 with 8 GB. This happily captured the data at 100 FPS, so that's good. stacking in AS!3 was really a lot quicker than before. The 16" 2560x1600 display is also a joy to use.

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while you are capturing, disable your  wifi first; then  Click on the start menu and open "virus an threat protection" , click on the manage settings button just under the virus and threat protection section;      and disable them all.  You will gain 150+ fps ability from your camera

 

Something about the real time virus  threat monitoring and cloud protection and automatic sample submission kills the camera record speed.      I guess it uploads your capture somewhere on the net while you are making it...

  

Turn them all back on when you are done capturing and ready to get back online.

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Following your progress with the tri band with interest Michael. Focus is soft but you can still see that there is a lot of great detail in there.

Once you get things sorted this is going to be a very impressive setup.

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1 hour ago, GreatAttractor said:

Very nice results!

But 10 000 frames (100 s) sounds a bit too much time-wise; at this scale I'd expect the features to evolve noticeably. Can you try processing just 2000-3000 frames?

Am experimenting with that. Will post the results later

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12 hours ago, GreatAttractor said:

Very nice results!

But 10 000 frames (100 s) sounds a bit too much time-wise; at this scale I'd expect the features to evolve noticeably. Can you try processing just 2000-3000 frames?

It certainly depends on the frame rate, and length of the video duration. 

 

I find that 8-10 second capture time per video  is the ideal amount for h-alpha; and   Realistically one only needs to use 250 frames for stacking.      Less stacked frames = less processing as well.

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10 hours ago, Kitsunegari said:

It certainly depends on the frame rate, and length of the video duration. 

 

I find that 8-10 second capture time per video  is the ideal amount for h-alpha; and   Realistically one only needs to use 250 frames for stacking.      Less stacked frames = less processing as well.

I find 250 frames often leads to noisy results, I find, especially working at F/30 and a quite narrow 0.3 Å bandwidth. I might get a new filter that matches my newer, more sensitive cameras better. A better grade filter may also have higher transmission

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17 hours ago, michael.h.f.wilkinson said:

I find 250 frames often leads to noisy results, I find, especially working at F/30 and a quite narrow 0.3 Å bandwidth. I might get a new filter that matches my newer, more sensitive cameras better. A better grade filter may also have higher transmission

IT does introduce some noise; especially if you over do it on the processing. USually it is not noticeable unless you have the gain cranked up.  What are your typical exposure , gain and gamma settings for capture?       Using a 0.3angstrom filter ,  you will experience longer exposure times because they are dimmer than a wider bandpass.

 

Unfortunately on the solar spectrum and daystar filters the real handicap is in the  blocking filter used in them;   These  gradually die in storage and overtime a performance loss occurs.;  this is first  noticed by requiring longer exposure times :(      The mica typically stays good however.

 

Placing the SS and Daystar stuff  in a box exposes them slowly to  damaging environment factors like car pollution,  and humidity; even residual vapors of  in home chemicals such as paint ,floors and plastics; airconditioners and heaters.    Sadly the filters suck this invisible  stuff up like candy unless you vacuum seal it in a silica bag  :(

 

Also the amount of exposure to sunlight was predetermined to cause a gradual death, regardless of energy rejection.   These two filters (red and gold)   are designed to fail to protect the valuable mica.

 

 

0.3angstrom filters are the best out there, and solar spectrum is the leading manufacture brand currently; so i doubt you will find anything better.        The two blocker and trim filters are sourced from andover optical and they have limited shelf life, so this is the unfortunate nature of these systems.   Sometimes Mark Wagner can upgrade these for you to a better suited bandwidth that can brighten up the system a bit; but the 0.3a mica is always going to be dimmer than a 0.5a system.

 

The sundancer2 by solar spectrum is supposed to be a remedy for the expiration date on filters,   with a sacrifice of etalon size and bandwidth  for life time extension.        It sports the baader planetarium name, but is still made by solar spectrum.   They are 0.65a and are likely the next best option,  the longevity factor alone is very attractive.  

 

 

I do agree with the camera statement,  perhaps you can find one with greater sensitivity in h-alpha.   Some cameras now are well suited for near infrared light and would indeed provide a brighter image.   Using such a high focal length is going to decrease image brightness;  so trying to maximize efficiency is certainly worth investing in to get the most of the filter you already have.          I did this with my calcium system,  found one that had 85% quantum efficiency at my desired wavelength and it was immediately noticeable when i used a long focal length.   Most cameras are less than 50% efficient below 400nm;  so you can imagine boosting this to 85% would logically provide an improvement somewhere and it does.  

 

 

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