Advice on refractor for WL

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nebulabru
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Advice on refractor for WL

Post by nebulabru »

Hello,
I want to start making solar observations in white light with a solar wedge, I am going to buy one from Lunt in 1 1/4", I would like you to recommend a good refractor for this purpose, I don't know if it should have an ED lens or with a achromatic is enough for me, yes, I don't like to see CA in the image. I had some achromatic a while ago and for certain objects it was painful.Also looking advice for others accessories,like filters..
Well, thank you very much in advance.
a greeting
Fran.


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Re: Advice on refractor for WL

Post by marktownley »

Hi Fran,

If you're restricting yourself to a 1-1/4" wedge I would get no more than a 100mm frac. What sort of budget do you have in mind? What sort of mount do you have?

Mark


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Re: Advice on refractor for WL

Post by nebulabru »

Hello,
Thanks for Your mail..
I've 400 or 500 euro for the refractor, and I 've two mounts, one SE Nexstar and one photo tripod Manfrotto...


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Re: Advice on refractor for WL

Post by marktownley »

Hi Fran

I would recommend a Skywatcher ED80 then, see if you can pick one up second hand with an upgraded focuser.

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Re: Advice on refractor for WL

Post by DeepSolar64 »

If you use filters like a Baader continuum 540nm filter an achromat will do just fine. The filter will remove any CA present. Without a filter I prefer an achromat F8 or above to reduce chromatic aberration.


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Re: Advice on refractor for WL

Post by nebulabru »

I've the possibility of use one Achromat 4" F 4.5..


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Re: Advice on refractor for WL

Post by marktownley »

nebulabru wrote: Tue Oct 11, 2022 8:26 am I've the possibility of use one Achromat 4" F 4.5..
That's very fast focal length!


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Re: Advice on refractor for WL

Post by Dennis »

nebulabru wrote: Tue Oct 11, 2022 8:26 am I've the possibility of use one Achromat 4" F 4.5..
Such things exist?
I would recommend you a proper telescope with f/7 or more for this purpose of high magnification work on the sun. Certain scope abberations should be better controlled at this focal ratios.


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Re: Advice on refractor for WL

Post by DeepSolar64 »

Dennis wrote: Tue Oct 11, 2022 9:30 am
nebulabru wrote: Tue Oct 11, 2022 8:26 am I've the possibility of use one Achromat 4" F 4.5..
Such things exist?
I would recommend you a proper telescope with f/7 or more for this purpose of high magnification work on the sun. Certain scope abberations should be better controlled at this focal ratios.

I actually prefer F8 or longer. I do have a little 70mm F7.1 refractor that does well though even though it has some CA if white light is done without a filter like the Baader Continuum.
Last edited by DeepSolar64 on Thu Oct 13, 2022 3:32 pm, edited 1 time in total.


Lunt 8x32 SUNoculars
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Meade Coronado SolarMax II 60 DS
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Re: Advice on refractor for WL

Post by nebulabru »

Then, no very good for WL... For the CA.!!


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Re: Advice on refractor for WL

Post by DeepSolar64 »

nebulabru wrote: Thu Oct 13, 2022 3:29 pm Then, no very good for WL... For the CA.!!
The CA is slight for the Orion70 but still there. It generally doesn't bother me. If I choose I can always use a filter like the Baader 540nm which increases the contrast of the spots and totally eliminates the chromatic abberation. Many people here use achromats for photosphere work but use filters at the eyepiece in addition to a wedge or over the aperture filter to boost detail and eliminate false color. I also have an apochromatic doublet with two ED glass elements that is false color free. My Astro-Tech AT72EDII which I use with the Altair wedge.

James


Lunt 8x32 SUNoculars
Orion 70mm Solar Telescope
Celestron AstroMaster Alt/Az Mount
Meade Coronado SolarMax II 60 DS
Meade Coronado SolarMax II 90 DS
Meade Coronado AZS Alt/Az Mount
Astro-Tech AT72EDII with Altair solar wedge
Celestron NexStar 102GT with Altair solar wedge
Losmandy AZ8 Alt/Az Mount
Sky-Watcher AZGTI Alt-Az GoTo mount
Cameras: ZWO ASI178MM, PGR Grasshopper, PGR Flea
Lunt, Coronado, TeleVue, Orion and Meade eyepieces

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