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Solar imaging with a 11" EdgeHD

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AstroED
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Solar imaging with a 11" EdgeHD

Post by AstroED » Mon Oct 26, 2015 6:31 pm

I was wondering if anyone Has rigged a 11" EdgeHD or any Celestron 11" for Ha imaging if so what is needed and can you share images? I am looking at the Lunt Ha filter for the Celestron that has 100mm aperture but not sure if that is the best or what else is needed.

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Re: Solar imaging with a 11" EdgeHD

Post by Valery » Mon Oct 26, 2015 11:10 pm

AstroED wrote:I was wondering if anyone Has rigged a 11" EdgeHD or any Celestron 11" for Ha imaging if so what is needed and can you share images? I am looking at the Lunt Ha filter for the Celestron that has 100mm aperture but not sure if that is the best or what else is needed.
I believe that I will start regular imaging of the Sun in H-a with my C11 quite soon. Within two weeks if the weather will cooperate at that moment. What I need is that my filter will returned from the coating Lab where it has been coated with anti-fungus coating. And a new cell for this ERF filter will come here in a week or so.
I have tested this full size two bands ERF filter with very promising results. This full size ERF filter has two main transmission bands - at 393nm and 656nm.
However, residual transmission at a green light allows to image the Sun there but without much of additional filtering. My best preliminary photos were taken at 540nm wave length and show full resolution of a 280mm aperture. Solar granulation is well seen in details. This confirms that filter has excellent optical quality and it will work even better at 656nm when my H-a etalon will be correctly fit to the C11 back.
My soonest next goal is to finish a 385mm ERF filter for my C14 scope. This filter is already in progress.

To image the Sun in H-a with C11 at full aperture you will need to buy such a full size ERF filter and appropriate H-a etalon. If you are interested in buying such a ERF filter for C11 and are interested in details, contact me via PM.


Valery.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: Solar imaging with a 11" EdgeHD

Post by michael.h.f.wilkinson » Tue Oct 27, 2015 9:54 am

I have observed through a C11 years back. They used an of-axis (sub aperture) ERF with Daystar filter (pre-Quark). Great views, but not necessarily better than you would get out of a 4" frac. Full aperture is of course better, but the prices of the ERFs are eye-watering.
Solar kit: GP-C8 with Thousand Oaks Solar filter, APM 80mm F/6, Lunt Herschel Wedge, Solar Spectrum 0.3Å H-alpha filter, Beloptic Tri-Band ERF (80mm free aperture), Thousand Oaks 90mm ERF, Coronado SolarMax II 60mm with Double Stack Unit. Lunt straight B1800 Ca-K module.

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Re: Solar imaging with a 11" EdgeHD

Post by Valery » Tue Oct 27, 2015 11:10 am

michael.h.f.wilkinson wrote:I
Full aperture is of course better, but the prices of the ERFs are eye-watering.
Full aperture views are MUCH MUCH better ( much more detailed and brighter ). Well worth of every penny invested.

Compare the views through a 40mm and a 90mm Coronado etalong.


Valery
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: Solar imaging with a 11" EdgeHD

Post by christian viladrich » Tue Oct 27, 2015 7:55 pm

Here are some first images taken by Thierry Legault with an C11 Edge-HD with a coated ERF Schmidt plate (ie. HAT 11 telescope) :
http://www.astrosurf.com/ubb/Forum3/HTML/044355.html
http://www.astrosurf.com/ubb/Forum3/HTML/044830.html
Christian Viladrich
Co-author of "Astronomie Planétaire"
http://www.astroplanetes.com/
Co-author of "Astronomie Solaire"
http://www.astronomiesolaire.com/

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Re: Solar imaging with a 11" EdgeHD

Post by Valery » Wed Oct 28, 2015 8:35 am

Separate full size multi band ERF filters should be more cost effective, more versatile solution.

Especially if a given C11 (or another scope) is of a good quality and can be used for other imaging
and visual applications.


Valery.
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: Solar imaging with a 11" EdgeHD

Post by AstroED » Wed Oct 28, 2015 1:45 pm

Thanks for the replies, I am getting dizzy with all the Solar imaging options for the up close details I desire, trying to decide between modding the 11"EdgeHD, buying a 152mm double stacked Lunt Ha, or a cheap 152mm Explore scientific with ERF filter and Daystar Quark or Quantum setup.

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Re: Solar imaging with a 11" EdgeHD

Post by Merlin66 » Wed Oct 28, 2015 5:49 pm

Valery,
How many pennies will be needed??
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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Re: Solar imaging with a 11" EdgeHD

Post by fjabet » Wed Oct 28, 2015 7:56 pm

My company have done two 11" HaT telescopes against more than a dozen 8". One for Thierry Legault as Christian mentionned, and one for me in replacement of my previous 8" HaT.
We made just a couple for a reason.
First making those telescope is outragously difficult because of the coating homogeneity that is critical to obtain on such a large aperture, the PTV over the aperture should be like 10%.
Also the coating should not be done using PVD. PVD needs to heat the substrat, which should be avoid for high precision optical flats, and is a fragile coating, it will degrade over time. If its cheap, it's likely PVD.
It must be done using IAD (Ion Assisted Deposit) or IBS (Ion Beam Sputtering). We use IBS, the most expansive method, that doesn't require high temp coating and give a very reliable coating. But the machines that uses this technology are usually rather small and very expansive.
That why we didn't use to have large ERF in the amateur landscape.

Another issue with 11" is that they are very difficult to use. It requires a very good seeing and basically I advice this kind of aperture for work class solar imagers such as Thierry. Even for me this 11" isn't really fun, my location isn't good enough.

A 203mm HaT is much easier to use visually and for imaging, and I'll take one for me in the next run. With the 8", there was just a few time when the seeing was so bad I didn't enjoy the view. Most of the time it was so great so I ended by mostly giving up imaging and just staring :)

That being said, the resolution of a 203mm is breathtaking when compared with any other commercial product.
You will find some high resolution images on my blog : http://astrochonum.com/index.php?option ... 6&lang=en

With a Chrominence Combo quark, you can have a 203mm Ha telescope that can use a binocular (most adviced for solar viewing) for half the price of a Lunt 152.

More details here : http://www.airylab.fr/AirylabUS/index.p ... &Itemid=66

Here is one of my best image.

Image
Looking for professional reports about telescopes ?

http://www.airylab.fr/AirylabUS/index.p ... &Itemid=57

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Re: Solar imaging with a 11" EdgeHD

Post by Valery » Thu Oct 29, 2015 12:56 am

I politely disagree with Frederic - concerning some points.

1. The cost of the optics and coating also greatly depends where they were produced. Not only the
method of manufacturing. For example, our highest precision optics 16" Ritchey-Chretien made with Ion Beam
Milling figuring (IMB process) cost 5-6x less than a 16" F/4 parabolic mirror made with IMB by Zygo or Itek Corp.
The same is with large flat windows and ERF filters.

2. Numerous examples of solar imaging with 10" to 14" apertures can be easily find in the Internet. Numerous amateurs doing solar imaging in a white light with 8" to 14" SCT. Full resolution can be relatively easy achieved. And imaging in H-a is significantly easier than in a white light (usually with a green filter added) due to lesser seeing influence and much higher contrast.
My experiments during last warm season confirm, that in those days when 150mm aperture can easily achieve maximum resolution (every second or third day), a full resolution can be achieved also with 280mm aperture. With a 356mm aperture the limit of resolution can be achieved a bit more rarely, but not really rarely. At least one or two session in a week. Sometime even 3 session in a week when the weather is stable.
In H-a this rate will be even higher. The keys for the success are:

a) time of imaging - these must be morning till 10h am. Seeing is the best between 7h and 10h am.
b) full aperture ERF filter - to keep unwanted heat out of the tube.
c) Sharp focus
d) very fast camera at least 80fps
e) short exposures - for maximize turbulence freezing.

Large ERF (say, for a C14) has another option. If the seeing does not cooperate, one can just stop the aperture with 6" off axis mask.


Valery
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: Solar imaging with a 11" EdgeHD

Post by Geremia Forino » Thu Oct 29, 2015 1:03 pm

Valery let me dream, send me a quote of a 14HD full aperture ERF :cool:

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Re: Solar imaging with a 11" EdgeHD

Post by KMH » Thu Oct 29, 2015 5:08 pm

Valery,
As a C11 owner this sounds really interesting, though I doubt my seeing here is ever good enough for even a C8. But I'm curious, how are you able to collimate the secondary mirror? Do you have a point source with enough intensity in the transmission bands?
Thanks,
Kevin

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Re: Solar imaging with a 11" EdgeHD

Post by Valery » Thu Oct 29, 2015 6:10 pm

KMH wrote:Valery,
As a C11 owner this sounds really interesting, though I doubt my seeing here is ever good enough for even a C8. But I'm curious, how are you able to collimate the secondary mirror? Do you have a point source with enough intensity in the transmission bands?
Thanks,
Kevin
Kevin,

You don't need any additional collimation when you install a full size ERF external filter. Just collimate your telescope at night and do not reverse it around declination axis - so, your scope will not loose the night collimation. Then install an external full size ERF, point the scope on the sun and go!

No problem at all with collimation.


Valery
"Solar H alpha activity is the most dynamic and compelling thing you can see in a telescope, so spend accordingly." (c) Bob Yoesle.

Largest full size 185 - 356mm Dielectric Energy Rejection Filters (D-ERF) by ARIES Instruments.

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Re: Solar imaging with a 11" EdgeHD

Post by KMH » Fri Oct 30, 2015 12:40 am

Kevin,

You don't need any additional collimation when you install a full size ERF external filter. Just collimate your telescope at night and do not reverse it around declination axis - so, your scope will not loose the night collimation. Then install an external full size ERF, point the scope on the sun and go!

No problem at all with collimation.


Valery[/quote]


OK - thanks - I misunderstood. I had thought the ERF coatings were deposited directly onto the correction plate.

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Re: Solar imaging with a 11" EdgeHD

Post by marktownley » Sun Nov 01, 2015 9:23 am

Interesting topic chaps! I think the limiter for me is always going to be the seeing. I am considering a 8" HaT though, I must confess...
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http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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