Sun in H-Alpha 31th of January 2021
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Sun in H-Alpha 31th of January 2021
Cold and clear today also. The Sun however is rather quiet! In this image I have tried to push the shadows a bit more to make the prominences more visible.
Stack of the best 60% (1650 of 2751) images captured with an exposure time of 29ms and 30fps. Stacking done in Autostakkert 3, sharpening in AstraImage and contrast stretching in Adobe PhotoShop.
Best regards,
Arne
Equipment used for this image was a Coronado SolarMax 60 II w/BF15 filter, Baader 35nm H-Alpha filter and ASI ZWO 178MM camera. Everything mounted on a Sky-Watcher SolarQuest mount.Stack of the best 60% (1650 of 2751) images captured with an exposure time of 29ms and 30fps. Stacking done in Autostakkert 3, sharpening in AstraImage and contrast stretching in Adobe PhotoShop.
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
Well Arne, that is a great improvement for a day when there has been as little happening for quite some time on the disk and/or proms..
Very well done, and especially with the low-down Sun and this time of the years' weather too.
Cheers
Terry
Very well done, and especially with the low-down Sun and this time of the years' weather too.
Cheers
Terry
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Re: Sun in H-Alpha 31th of January 2021
Hi Arne,
Well done. For what do you have an additional 35nm H-alpha filter in your optical train ?
Well done. For what do you have an additional 35nm H-alpha filter in your optical train ?
regards Rainer
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Re: Sun in H-Alpha 31th of January 2021
I wondered that too.
It's nice to see images through a scope I use a lot visually.
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Re: Sun in H-Alpha 31th of January 2021
Good disk Arne, the sun is quiet!
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Re: Sun in H-Alpha 31th of January 2021
Great shot Arne!!!
Brian
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Re: Sun in H-Alpha 31th of January 2021
Wonderful!! even on a day with not many proms you have picked them out
Alexandra
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Re: Sun in H-Alpha 31th of January 2021
Thank you all!
I’m using the 35nm H-Alpha filter as an UV/IR-blocking filter. It reduces any off-band light leakage and makes the disc more uniform with more contrast as well as reducing reflections around the Sun.
Here’s a comparison I did with the same telescope (Coronado SolarMax 60 II w/BF15 filter) together with a Cemax 2x barlow and an ASI ZWO 1600MM Pro camera back in November
Without any extra filter: With 35nm H-Alpha filter: Both images were shot using the same gain and with a neutral gamma setting. Only the exposure time was adjusted to achieve the same max value (approx. 200). For the image without any extra filter that meant an exposure time of 49ms while exposure time had to be increased to 109ms to reach the same level with the 35nm H-Alpha filter. This really illustrates how much light outside this 35nm area is leaking through without the filter.
Both images where sharpened in Astra Image using the same settings. No further processing
Best regards,
Arne
I’m using the 35nm H-Alpha filter as an UV/IR-blocking filter. It reduces any off-band light leakage and makes the disc more uniform with more contrast as well as reducing reflections around the Sun.
Here’s a comparison I did with the same telescope (Coronado SolarMax 60 II w/BF15 filter) together with a Cemax 2x barlow and an ASI ZWO 1600MM Pro camera back in November
Without any extra filter: With 35nm H-Alpha filter: Both images were shot using the same gain and with a neutral gamma setting. Only the exposure time was adjusted to achieve the same max value (approx. 200). For the image without any extra filter that meant an exposure time of 49ms while exposure time had to be increased to 109ms to reach the same level with the 35nm H-Alpha filter. This really illustrates how much light outside this 35nm area is leaking through without the filter.
Both images where sharpened in Astra Image using the same settings. No further processing
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
It makes a difference! I wonder if it would make a difference visually?
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Re: Sun in H-Alpha 31th of January 2021
Thanks for sharing Arne, I'm all clouds here for the last couple of days and the forecast isn't good for me either.
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Re: Sun in H-Alpha 31th of January 2021
That's quite a difference Arne! Are you using the original blocking filter that came with the scope?
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Re: Sun in H-Alpha 31th of January 2021
Hi, Mark.
Yes, I'm using the BF15 filter that came with the scope. I have another BF15 filter that came with my SolarMax90, but I haven't had the chance to do any comparison between the two. That'll have to wait until it gets a bit warmer.
Best regards,
Arne
Yes, I'm using the BF15 filter that came with the scope. I have another BF15 filter that came with my SolarMax90, but I haven't had the chance to do any comparison between the two. That'll have to wait until it gets a bit warmer.
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
An incredible difference between the two setups!!!
Thanks for showing these.
Brian
Thanks for showing these.
Brian
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Photos: https://www.flickr.com/photos/185395281@N08/albums
10'x15 Roll-off Roof Observatory
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Re: Sun in H-Alpha 31th of January 2021
Obviously passing some extra IR light which the camera is picking up, you won't see this with your eye as it can't see this wavelength. Both Bob and I had exactly the same problem with the Solarscopes. Visually great by eye, but camera picked up the IR. Corrected by an extra blocking filter. Your 35nm filter is doing exactly the same job.
Alexandra
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Re: Sun in H-Alpha 31th of January 2021
Hi Arne,arnedanielsen wrote: ↑Mon Feb 01, 2021 10:13 pm Thank you all!
I’m using the 35nm H-Alpha filter as an UV/IR-blocking filter. It reduces any off-band light leakage and makes the disc more uniform with more contrast as well as reducing reflections around the Sun.
Here’s a comparison I did with the same telescope (Coronado SolarMax 60 II w/BF15 filter) together with a Cemax 2x barlow and an ASI ZWO 1600MM Pro camera back in November
Without any extra filter:
Sun_112112_Ha_20201127_ZWO ASI1600MM Pro_lapl5_ap3218_Sharpened.jpg
With 35nm H-Alpha filter:
Sun_110421_Ha_20201127_ZWO ASI1600MM Pro_lapl5_ap3193_35nm_Sharpened.jpg
Both images were shot using the same gain and with a neutral gamma setting. Only the exposure time was adjusted to achieve the same max value (approx. 200). For the image without any extra filter that meant an exposure time of 49ms while exposure time had to be increased to 109ms to reach the same level with the 35nm H-Alpha filter. This really illustrates how much light outside this 35nm area is leaking through without the filter.
Both images where sharpened in Astra Image using the same settings. No further processing
Best regards,
Arne
Thank you for the explanation. One more question: Are you 100% in the best etalon adjustment e.g in band ?
Thanks Rainer
regards Rainer
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Re: Sun in H-Alpha 31th of January 2021
Indeed. My 2 coronado bf15s use quite different ITF filters and one 'works' with my SM90, one does not (same thing as Arnes image). These are stock blocking filters too, not mods.Montana wrote: ↑Tue Feb 02, 2021 4:18 pm Obviously passing some extra IR light which the camera is picking up, you won't see this with your eye as it can't see this wavelength. Both Bob and I had exactly the same problem with the Solarscopes. Visually great by eye, but camera picked up the IR. Corrected by an extra blocking filter. Your 35nm filter is doing exactly the same job.
Alexandra
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Re: Sun in H-Alpha 31th of January 2021
Nice FDs.
Just an observation and comment if I may? 109ms is really slow. I'd be expecting at least 10-20 ms, which is what I get with my Lunt 60 double stacked (so I'd expect yours to be similar at least). The issue for you with such a slow speed (at over 1/10th second) will be the setup's sensitivity to the seeing conditions. Are you sure it is 109ms and not 10.9 ms (and also 4.9 ms rather than 49 ms)?
Maybe it's due to the low winter Norwegian Sun
Stu.
Just an observation and comment if I may? 109ms is really slow. I'd be expecting at least 10-20 ms, which is what I get with my Lunt 60 double stacked (so I'd expect yours to be similar at least). The issue for you with such a slow speed (at over 1/10th second) will be the setup's sensitivity to the seeing conditions. Are you sure it is 109ms and not 10.9 ms (and also 4.9 ms rather than 49 ms)?
Maybe it's due to the low winter Norwegian Sun
Stu.
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Re: Sun in H-Alpha 31th of January 2021
A very illuminating thread.marktownley wrote: ↑Tue Feb 02, 2021 6:47 pmIndeed. My 2 coronado bf15s use quite different ITF filters and one 'works' with my SM90, one does not (same thing as Arnes image). These are stock blocking filters too, not mods.Montana wrote: ↑Tue Feb 02, 2021 4:18 pm Obviously passing some extra IR light which the camera is picking up, you won't see this with your eye as it can't see this wavelength. Both Bob and I had exactly the same problem with the Solarscopes. Visually great by eye, but camera picked up the IR. Corrected by an extra blocking filter. Your 35nm filter is doing exactly the same job.
Alexandra
Mark - did Coronado change its ITF filters at some stage or did you make the change yourself to one of your stock BF15s?
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Re: Sun in H-Alpha 31th of January 2021
Something changed, and (for once!) it wasn't me who changed itHighbury Mark wrote: ↑Tue Feb 02, 2021 8:21 pm A very illuminating thread.
Mark - did Coronado change its ITF filters at some stage or did you make the change yourself to one of your stock BF15s?
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Re: Sun in H-Alpha 31th of January 2021
Good point Stu.Carbon60 wrote: ↑Tue Feb 02, 2021 8:07 pm Nice FDs.
Just an observation and comment if I may? 109ms is really slow. I'd be expecting at least 10-20 ms, which is what I get with my Lunt 60 double stacked (so I'd expect yours to be similar at least). The issue for you with such a slow speed (at over 1/10th second) will be the setup's sensitivity to the seeing conditions. Are you sure it is 109ms and not 10.9 ms (and also 4.9 ms rather than 49 ms)?
Maybe it's due to the low winter Norwegian Sun
Stu.
Or a rusted / degraded ITF? When was the last time you checked it Arne?
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Re: Sun in H-Alpha 31th of January 2021
That's my conclusion as well.Montana wrote: ↑Tue Feb 02, 2021 4:18 pm Obviously passing some extra IR light which the camera is picking up, you won't see this with your eye as it can't see this wavelength. Both Bob and I had exactly the same problem with the Solarscopes. Visually great by eye, but camera picked up the IR. Corrected by an extra blocking filter. Your 35nm filter is doing exactly the same job.
Alexandra
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
Hi Rainer,
I can't say that I’m absolutely 100% sure, but I think it’s close to as good as it gets with this scope.
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
Hi Stu,Carbon60 wrote: ↑Tue Feb 02, 2021 8:07 pm Nice FDs.
Just an observation and comment if I may? 109ms is really slow. I'd be expecting at least 10-20 ms, which is what I get with my Lunt 60 double stacked (so I'd expect yours to be similar at least). The issue for you with such a slow speed (at over 1/10th second) will be the setup's sensitivity to the seeing conditions. Are you sure it is 109ms and not 10.9 ms (and also 4.9 ms rather than 49 ms)?
Maybe it's due to the low winter Norwegian Sun
Stu.
Yes, 109ms is indeed slow and as you say it makes it very vulnerable to poor seeing. The exposure time is correct however (also verified by the drop from 17fps for the 49ms exposure to 9fps for the 109ms exposure). I think the long exposure can be explained by the sum of the following factors:
• Low altitude of the Sun
• Using the 2x CeMax to for doubling the focallength and increasing the f/number to 13.3
• The small 3.8µm pixel size of the 1600MM Pro.
• Gain setting of 140
The good thing is that with only 60mm of aperture the resolution is rather limited (approx. 1,93” according to Dawes limit) so it’s not that sensitive to poor seeing.
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
Hi Mark,marktownley wrote: ↑Tue Feb 02, 2021 8:26 pm Good point Stu.
Or a rusted / degraded ITF? When was the last time you checked it Arne?
I bought the SolarMax 60 II second-hand last Autumn. It looked ok when I inspected it then, but I should maybe do a more thorough check.
I will also try to testing the to BF15 filters against each others, but that will have to wait until the days get longer and the weather gets warmer.
Best regards,
Arne
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Re: Sun in H-Alpha 31th of January 2021
Wonderful result
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