Big Doubts with solar refractor for White light.

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Pluton
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Big Doubts with solar refractor for White light.

Post by Pluton »

Hello,
I'm looking for information on solar observation in white light, visually, with some kind of achromatic refractor.
My idea is to mount it on an azimuth azimuth mount type Vixen Porta mount or mount Astro-Tech.
I read that a short refractor type 4.7 "F / 5 (120mm / 600) and has good resolution for different characteristics of the photosphere, including granulation.
At first I thought at ED80, ED70 or similar refractor.
I also want to put a solar Wedge, and also use it for a future observation in H-alpha.
My question is:
- What kind of refractor is the best idea I have suit?
- A 80-70 mm ED refractor?
- A larger aperture achromatic refractor, 4 "or 4.7" with short focal .. and higher resolution?
- Being achromatic refractor would affect CA and the spherical aberration in the visual images?
As you can see, I have many doubts ..
Any suggestions, feedback or comments in this regard are very welcome !!
Thank you very much.
Paul


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Re: Big Doubts with solar refractor for White light.

Post by grimble_cornet »

So many variables............

About 2 years ago, I bought an Equinox 120 ED Refractor (900 f7.5) to use with a Baader ceramic solar wedge and have been quite pleased with the results.
However, since then I have tried 3 other refractors either out of curiosity or because they were more convenient when travelling.
My Equinox 80 (500 f6.25) works very well and I often use it for full discs and x2 Barlow shots when I can't be bothered to get the 120 out.
I bought a Tal 100 (1000 f10) achromat recently to use for CaK imaging but gave it a try with the Baader wedge.
Finally I have a little Lunt 60 (500 f8.3) which came with the CaK filter. I assumed it would be too small to produce anything worthwhile in whitelight but, I was wrong!
When traveling I often just take the Lunt 60 with its CaK unit plus the Baader wedge. Certainly good enough for full discs and ok with a Barlow in decent seeing.

Here are images taken with the 4 scopes if you are interested.
Equinox120 ZWO ASI120MM 2014 2807 1048 ut.jpg
Equinox 80 2014 0724 1245 ut.jpg
Tal ZWO ASI120MM Baader Wedge 24th July 2014.jpg
Lunt 60 2014 0724 1301 ut.jpg
None of them were taken under very good conditions and the processing leaves something to be desired but I think they tell a story.
The Equinox 120 shows more detail and the granulation is much more obvious - as you would expect.
The Equinox 80, Tal 100 and Lunt 60 shots were taken at the same time and processed in the same way as part of an experiment. I am amazed that there is so little difference between them!

Here is a very early shot I took with the Equinox 120. It shows a more complex spot group BUT...... in 2012 my capture and processing techniques were both pretty poor so this is only a guide rather than an indication of what the scope can produce.
Equinox 120 Baader wedge x2 Barlow 2012 0730 1422 ut.jpg
Finally, here is a selection of shots taken in the same era (2012) using the Equinox 80 with a SolarFilm filter:
Equinox 80 - Solarfilm August 2012.jpg
Hope this is of some help,

Mike


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Selection of Solar and Deep Sky images on Flickr: https://www.flickr.com/photos/mikegarbett/
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Re: Big Doubts with solar refractor for White light.

Post by swisswalter »

Hi Paul

welcome to that wonderful site. HAve fun in the sun. Where are you from? Local seeing can be limiting the useful aperture. 80-100 mm can work nicely more often than 120 -130


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
Pluton
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Re: Big Doubts with solar refractor for White light.

Post by Pluton »

Mike. thanks for this fabulous shots...but for visual in your opinion which is the more versatile?
Walter, very grateful for your welcome, I live in Spain.
Regards
paul


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Re: Big Doubts with solar refractor for White light.

Post by GUS »

Hi Paul, welcome to the site. I use an Orion 80ED with Lunt solar wedge on a vixen Porta mount for white light(visual only) and it provides great views.


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Re: Big Doubts with solar refractor for White light.

Post by Pluton »

Thank you Gus, for your welcome.
Your Lunt Solar Wedge is 1.25" or 2"..? You use a polarized filter or a Solar Continum Baader filter?
In your opinion a ED80 is valid for details on granulation,pores,faculas..spot..or it is more affair of seeing conditions?
regards,
paul


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Re: Big Doubts with solar refractor for White light.

Post by grimble_cornet »

Paul, I'm not a visual observer so anything I say should be taken with a big pinch of salt :roll:

If we accept that there probably is NO IDEAL SCOPE for anything, then everything involves some compromise :?

I'm a great believer in the idea that the BEST scope is one that actually gets used :lol:

My Equinox 120 resolves the most detail on the Sun BUT......... its heavy, demands a good mount and only really delivers when the seeing is good. It doesn't get taken out very often :oops:

My Lunt 60 is light, easy to use on any mount and can be used for CaK and white light by simply changing the diagonal. BUT, although it works very well for CaK, it doesn't really give the detail I want in white light. It is my standard travel scope but at home.......

The Equinox 80 offers almost as much convenience as the Lunt 60, gives better images/views in white light and is always handy because its also my standard deep sky imaging scope. :seesaw


With regard to focal length, f numbers etc..............
Very short, wide field, fast scopes (f4-6)are not really suitable in my humble opinion. They tend to have optical distortions and need a lot of amplification (Barlows or Powermates) to show much detail.
Long focal length, slow scopes (f10) are often recommended for planetary use. It is much easier to make an optically excellent f10 scope than an f4 one and you get more native magnification without needing to use Barlows or short eyepieces BUT you may struggle to get a full disc when imaging - might not be an issue visually?

I find that the Equinoxes - 120 and 80 - are a good compromise as I can see/image everything from an overview of the surface to highly detailed spot structure :P

A final point...... make sure the scope you choose will reach focus with the wedge you buy. Many people (including me) have had problems with the Baader wedge FOR IMAGING as it has a longer light path than most diagonals. My Equinoxes work if I replace the wedge's rather long eyepiece tube with a low profile one. The Tall 100 won't reach focus even with the low profile tube! This is PROBABLY not a problem visually but check before you buy if possible (especially if you think you might be tempted to try imaging at some point).

Just my opinions - others will most certainly disagree :evil:

Here are a couple of Equinox 120 shots from this morning in poor seeing. Might give you some idea what can be seen although the eye does a much better job than the camera in poor seeing :oops:

This is at native focal length:
Equinox 120 Grasshopper3 2014 3009 0811 ut colour.jpg
This is with a x2.5 Powermate:
300914_Grasshopper3 GS3-U3-28S5M_081551 s.jpg
This is getting silly with x2.5 Powermate plus x2 Barlow = 4500mm focal length!
Equinox 120 x2_5 Grasshopper3 2014 3009 0853 ut colour.jpg
Equinox 120 x2_5 Grasshopper3 2014 3009 0853 ut colour.jpg (448.16 KiB) Viewed 5003 times
Best wishes,

Mike


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Mike Garbett

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Re: Big Doubts with solar refractor for White light.

Post by swisswalter »

Hi Paul

I second what Mike wrote


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: Big Doubts with solar refractor for White light.

Post by grimble_cornet »

Paul, Walter REALLY knows what he is talking about (I just sound as if I do)



WoW Walter - I am humbled :oops: :beanie:


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Re: Big Doubts with solar refractor for White light.

Post by swisswalter »

;) Mike , don't put your light under the chair


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: Big Doubts with solar refractor for White light.

Post by GUS »

Hi Paul, the wedge is the 1.25" version and I use both the polarizer and the continuum filters. What you see can be affected by local weather conditions, but generally when conditions are good the ED 80 can show some amazing structure in spots at high mag, but granulation always looks good to me at low power, and I personally like the Continuum filter as opposed to the polarizer(others will differ) and I don't mind the green colour either. I also use Binoviewers (Williams Optics)with the ED80 and this takes the visual experience to another level. And cameras will come to focus with it. I have the Orion ED80, not sure about the other versions of it.


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Re: Big Doubts with solar refractor for White light.

Post by Pluton »

The Lunt Wedge solar 1.25" is OK for the Orion ED80?
Thanks again for All response.
Paul


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Re: Big Doubts with solar refractor for White light.

Post by swisswalter »

Hi Paul

the LUNT wedge will work if you have enough inward travel


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
ForrestLockhart

Re: Big Doubts with solar refractor for White light.

Post by ForrestLockhart »

Hi Paul,
I recently purchased a Chinese-made 100mm Lunt Engineering ED refractor for use with my Lunt Herschel wedge. Used with a linear polarizing or Baader Continuum filter for visual work and public Solar observing, I have been very satisfied with the combination. Night use of the refractor has also been pleasing. While residual color at low magnification is negligible, I do detect some color on bright objects at above 120x or so. That said, I did boost magnification to slightly above 200x to observe Saturn on a night of exceptional seeing. The view was beautiful, with ring detail quite sharp.
Since I'm not doing imaging yet, the new scope/wedge combination has fulfilled all my immediate observing needs. The scope doesn't compare to my 4" TeleVue NP-101, but it was far less expensive on the pocketbook.
Forrest


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Re: Big Doubts with solar refractor for White light.

Post by grimble_cornet »

Glad to hear its all working out Forrest.


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ForrestLockhart

Re: Big Doubts with solar refractor for White light.

Post by ForrestLockhart »

Thanks Mike,
The Baader continuum filter was a pleasant surprise when I first observed the Sun with the new scope/wedge rig. I was impressed with the improved apparent resolution over either the linear polarizer or the front-end glass filter. Why apparent? Compared to the polarizer, I'm not totally sure if I'm seeing more through the continuum filter, or I just think I am. A green Sun doesn't bother me, but it seems to put the public off a bit, so when out 'among them' I use the polarizer.
I'll be donating my 2" Herschel Wedge to our new academic imaging observatory when it is finished next year, and will probably purchase a 1.25" version for my own use. What downside do you see to that decision. Keep in mind that most or all of my meager imaging efforts will be at the new observatory, while my personal use will be in my yard or out with the public.
Your thoughts, all?
Forrest


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Re: Big Doubts with solar refractor for White light.

Post by grimble_cornet »

Having tried solarfilm and the Baader wedge side by side on several scopes I would say the difference is no more than 10% for visual use and maybe a little more for imaging?
I prefer the continuum filter for imaging but I can understand people being put off by the green sun :lol:


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Mike Garbett

Selection of Solar and Deep Sky images on Flickr: https://www.flickr.com/photos/mikegarbett/
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