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Did a practice run on the Sun, looks blurry

32 replies to this topic

#26 brooklynlou

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Posted 07 April 2024 - 06:18 PM

Thousand Oaks from Agena is not a scam. I got some and it works. Depending what you want to do with it, Spectrum glass is better but more expensive. ERF may be necessary for larger apertures.


Second Thousand Oaks. Love my glass filter from them. Built like a tank.

#27 reubanks

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Posted 07 April 2024 - 07:10 PM

Agena Astro are indeed good people, and legit.

 

IMO, of course...



#28 steveward53

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Posted 08 April 2024 - 01:05 AM

Thousand Oaks from Agena is not a scam. I got some and it works. Depending what you want to do with it, Spectrum glass is better but more expensive. ERF may be necessary for larger apertures.

There is no glass filter produced these days that uses optically flat glass of a quality that makes it outperform Baader film.

 

And could you explain the "ERF may be necessary for larger apertures" statement ... ?

 

It is not a requirement with any front end photosphere solar filtering medium that I've ever encountered .



#29 gstrumol

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Posted 08 April 2024 - 07:26 AM

+1 on Steve's comment - the Baader solar film is better than any basic (i.e., not outrageously expensive) glass solar filter.



#30 DeepSky Di

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Posted 08 April 2024 - 08:11 AM

I don't have an ERF and I don't do solar with my SCTs. However here's some CN discussion and a video:

 

https://www.cloudyni...dvice-on-a-erf/

AstroStace fitting an ERF and explaining what it does: https://youtu.be/3Pn...led8qR60zbKF73e



#31 unimatrix0

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Posted 19 April 2024 - 10:53 AM

+1 on Steve's comment - the Baader solar film is better than any basic (i.e., not outrageously expensive) glass solar filter.

I received Baader solar filter film I did the same thing, but the Sun still came out blurry and I went back and forth with the autofocuser. 

 

Somehow maybe my rig just can't focus on the sun right? 

 

It's an astrophotography rig, so I don't know why I can't focus on the sun.  I can focus on the stars precisely and the moon, but not on the Sun. 

 

I'm gonna list the components from the main objective to the camera,  so someone maybe can spot a problem: 

 

Solar filter (Baader)  placed into a 3d printed cap- not tight - taped around inside the edge with black (cloth material) tape. 

Svbony 550/ 80mm triplet 

Svbony 1X field flattener

UV/IR filter screwed in the end of the flattener

55mm spacers

071mc pro color APS-C camera

also - ZWO EAF autofocuser

Sharpcap Pro 

Camera gain and exposure adjusted so it's not clipping on either ends. 

Why is this rig able to make great pictures at night on nebulae and galaxies  but unable to focus on the Sun?  confused1.gif

 

Here was the best focus I could achieve
https://photos.app.g...ZTiG3CGFzN2Fho8


Edited by unimatrix0, 19 April 2024 - 10:56 AM.


#32 JimTheEngineer

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Posted 19 April 2024 - 09:35 PM

I’m definitely no expert, but it looks like you are using a slow DSO camera with real low capture frame rates, and exposure time settings are too high. Try adjusting your exposure time to 100 µs and pump gain up so you cover about 60-70% of the histogram. Take about 2mins of video. Then use AS!3 to stack the video file. It would be better if you had a planetary camera that has much better speed than your DSO camera.

Put a towel over your head and the screen you use to focus and use the fine focus knob and rotate back and forth on each side of focus on a big sunspot. Get it to the point where it is darkest with the most contrast. Seeing will bounce around a little bit, but if you can take a couple thousand frames, you can capture maybe 10-15% of the best ones and get a stacked in focus image…

Edited by JimTheEngineer, 19 April 2024 - 09:59 PM.


#33 Bob Campbell

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Posted 22 April 2024 - 11:49 PM

I received Baader solar filter film I did the same thing, but the Sun still came out blurry and I went back and forth with the autofocuser. 

 

Somehow maybe my rig just can't focus on the sun right? 

 

It's an astrophotography rig, so I don't know why I can't focus on the sun.  I can focus on the stars precisely and the moon, but not on the Sun. 

 

I'm gonna list the components from the main objective to the camera,  so someone maybe can spot a problem: 

 

Solar filter (Baader)  placed into a 3d printed cap- not tight - taped around inside the edge with black (cloth material) tape. 

Svbony 550/ 80mm triplet 

Svbony 1X field flattener

UV/IR filter screwed in the end of the flattener

55mm spacers

071mc pro color APS-C camera

also - ZWO EAF autofocuser

Sharpcap Pro 

Camera gain and exposure adjusted so it's not clipping on either ends. 

Why is this rig able to make great pictures at night on nebulae and galaxies  but unable to focus on the Sun?  confused1.gif

 

Here was the best focus I could achieve
https://photos.app.g...ZTiG3CGFzN2Fho8

Not sure if you want any additional feedback on this issue, but a couple things:

 

1) It looks like you are not using the planetary/lunar/solar stacking feature of 4.1. Try using that, along with feature tracking. You can stack a given percentage of frames, and you can see the changes when you go through different focus settings to compare.

 

2) I did an astronomy tools analysis of your FL and camera, and you look to be undersampled. Maybe try it with a 2x or 3x barlow. (Can't remember if you had tried that)

 

3) Just because it is cold does not mean that the sun doesn't heat the column of air to create not that great seeing. Sure, its obvious when its 100F, but what is important is the temperature gradient that is created even when the ambient is much cooler.

 

Bob





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