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M57 with 5080mm focal length / start of an experiment

astrophotography
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#1 meegja

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Posted 04 July 2020 - 03:51 PM

Short intro. My name is Menno, I am from the Netherlands. I am not really mobile so I am stuck under a Bortle 8 sky. But that is not stopping me.

Busy with astronomy since 1980 but not much with my own telescopes. Have experience with a simple 150/900mm Newton and simple, normal camera.

But this year I bought a complete new setup. First with the objective to capture moon, planets and sun (like I am used too) but discovered that my Meade LX65 8" f/10 ACF OTA does rather good DSO. So I upgraded right away smile.gif

 

And I am (very) experimental. When I am told "That is impossible", I'll first try it and then agree or disagree.

Like this capture of M57 with a focal length of 5080mm. I was busy with finetuning the collimation, so used a TeleVue PowerMate 2.5x Barlow on Vega. That made my scope f/25 or 5080mm FL. But too much seeing for that, so for fun I slewed to the nearby M57. 

And here almost all the credit goed to my mount: an Ioptron CEM25EC. Just for fun I did set a capture time of 30 seconds and the tracking was/is SO good. No guiding, just tracking. I do use a manual input for the Sidereal Rate though. But all this unprepared since I planned only for collimation.

So made a few darks and did 35 x 30 seconds. And after stacking and processing, I got this. I was just blown away: all this unguided in this, tiny, tiny FOV and,  even unprepared, almost steady stars.

 

This capture is far from perfect but it promises so much more when prepared and collimated. And new camera: this was captured with a Zwo ASI385MC (planetary camera smile.gif) But I have a Zwo ASI294MC Pro now also. Still have to use it though: clouds, rain and clouds.
Plus ofcourse: more experience. Only been busy with this setup and DSO for 3 months now.

Despite it not being perfect, I thought to share it here anyway. Also a bit with the message to other beginners to try things. Even when you think it's impossible: try, see and learn smile.gif

 

Ioptron CEM25EC mount (no guiding)
Meade LX65 8” f/10 ACF OTA
TeleVue Powermate 2.5x barlow
Baader Neodymium filter
Zwo ASI385MC camera

 

Capture with SharpCap: 35 x 30 seconds, gain 190 (of 600), 10 darks.
AutoStakkert for stacking (not enough data for DeepSkyStacker)
Processed in PS: Curves and Levels, Shadows/Highlights, colors, contrast, noise reduction.

 

M57_big.jpg


Edited by meegja, 04 July 2020 - 03:53 PM.

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#2 Tapio

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Posted 04 July 2020 - 04:01 PM

That's nice - I like 'why not' and 'what if' thinking.

EC model should do pretty well unguided but over 5000 mm fl is pushing it.


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#3 meegja

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Posted 04 July 2020 - 04:11 PM

That's nice - I like 'why not' and 'what if' thinking.

EC model should do pretty well unguided but over 5000 mm fl is pushing it.

Ah yes, for sure pushing it :) But that's why I really consider it for now as an experiment. This short, unprepared session shows promise though.



#4 yzhzhang

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Posted 04 July 2020 - 04:21 PM

Interesting and Amazing! Definitely pushing but seems like it turns out OK. Well done!


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#5 F.Meiresonne

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Posted 04 July 2020 - 04:26 PM

Seems the experiment succeeded.

 

M57 troubles me too. It is a nice object, with nice color but soo small...

 

I experimented with a Barlow, but the Barlow produced a blue halo. A pity otherwise i might have worked.

Bringing my F7 714 mm to 1400 mm over even over.


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#6 Stelios

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Posted 04 July 2020 - 04:40 PM

The question about the Barlow is--does it really do anything more for you than not using it and zooming in would do? Your image scale at 5080mm is 0.111"/px, so it's rather doubtful. 

 

I don't know what seeing is in your location, but I think you should try imaging at native F/10 and even at F/6.3. You may be surprised to see little if any difference.


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#7 Gipht

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Posted 04 July 2020 - 05:26 PM

30 second exposures at a 5000mm focal length requires a bright object, and M57 fits the bill.  Nice work!


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#8 sunnyday

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Posted 04 July 2020 - 08:20 PM

nice , i like the effect and colors , thanks .


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#9 schmeah

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Posted 05 July 2020 - 12:27 AM

Very impressive. On an ioptron CEM25C, at that FL and with no guiding. Impressive to say the least. Keep up the good work.

 

Derek


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#10 meegja

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Posted 05 July 2020 - 02:25 AM

The question about the Barlow is--does it really do anything more for you than not using it and zooming in would do? Your image scale at 5080mm is 0.111"/px, so it's rather doubtful. 

 

I don't know what seeing is in your location, but I think you should try imaging at native F/10 and even at F/6.3. You may be surprised to see little if any difference.

Seeing is most of the time not good here being it in the middle of a city.

But I did capture M57 with f/10 a week before this experiment (prepared and way more captures, so more detail). Made a comparison by zooming into that one until it had roughly the same size as the f/25 one (only 35 captures). And no, there is not much difference. The stars inside the nebula are a bit sharper with the f/25.
So would it look roughly the same? Yes, I think you're right in that.

Would using the Barlow, tweaking the mount, getting the best settings with capturing and learning what is possible and what not be more fun? Definitively yes smile.gif

To use a cheesy phrase: for me the journey to the result is as important as the result.

 

M57_f.jpg



#11 meegja

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Posted 05 July 2020 - 02:28 AM

Seems the experiment succeeded.

 

M57 troubles me too. It is a nice object, with nice color but soo small...

 

I experimented with a Barlow, but the Barlow produced a blue halo. A pity otherwise i might have worked.

Bringing my F7 714 mm to 1400 mm over even over.

I had the same with another Barlow I used to have. Did some research and this one looked best. It was 4 or 5 times the price of my previous Barlow though crazy.gif



#12 F.Meiresonne

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Posted 05 July 2020 - 03:55 AM

The question about the Barlow is--does it really do anything more for you than not using it and zooming in would do? Your image scale at 5080mm is 0.111"/px, so it's rather doubtful. 

 

I don't know what seeing is in your location, but I think you should try imaging at native F/10 and even at F/6.3. You may be surprised to see little if any difference.

That was actually the experiment...

 

But due to the blue or white artifact it became a failure. The Barlow was unexpensive and T2 threaded.

But i could use it on the moon with succes.




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