looking a refractor for solar white light

[pluton]

  Hello,
  I'm looking for opinion on some good refractor, which do well in sun observation of white light, for a Herschel prism (solar Wedge), I am not clear which is better an achromatic or Apo, I would use it on azimuth mount type Vixen Porta or similar.
I have doubts between ED80, for example, does not weigh much and manageable .. or some Achromatic 4 "heavier but with better resolution, perhaps also some ED100 or ST 120 F / 5, but perhaps the short focal length do not go well for solar observation .. I do not know.
For me the important thing is that the refractor is manageable, provide good visual picture and have a good degree of resolution, he can see the "solar granulation", apart from spots, pores, beaches ... in the photosphere.
Thank you very much for your advice
Greetings
Paul

                       

[Stu]

An ED80 will give you very good results, as will something like a Vixen 80M. If manageability is key, I think sticking around the 80mm mark makes sense and the views are very good. I use a TV85 which is excellent but those I mention will give very similar results.

Stu

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[Pig]

Paul,

I have an Equinox 80mm pro that I use for both astro and solar, works excellent with the Hershel wedge.

The black scope in the image below. (does not show the Hershel wedge in this image)

[Qualia]

Oh that is lovely, Shaun. Absolutely gorgeous set up

Pluton, I use Lunt's Herschel Wedge with the Tal 100rs and get cracking results in terms of purely visual work. There's an interesting thread here running through the given virtues of the Tal 100rs and ED100 which might be of interest.

[rwilkey]

Hi Paul, I do exaclty that with my C100ED on a Vixen Porta II mount and it works very well.  However, I prefer to use the Baader film at the front, don't like the thought of any strong light going through the OTA, pics follow:

[Moonshane]

I use a Vixen 80M f11 frac with a Lunt wedge and the views are quite superb. Sharper on the whole than my 6" f11 dob with film but importantly also more stable so the view is 'rock solid' given a very minimal expectation on seeing. Granulation (with a Baader solar continuum filter and olarising filter) is subtle but certainly visible and the pores, umbra, penumbra and fasculae details are quite stunning. I wuld certainly recommend this arrangement although consider the length of a long achro tube vs. the eyepiece height at the zenith. an 80mm ED scope would almost certainly be a good match for my achro but in a shorter package like Shaun's set up about or Stu's TV frac.

[Stu]

The Equinox is certainly a lovely short package, 500mm vs 600mm f/l for the Evostar 80ED.

This is the TV85 with Herschel Wedge, very lovely but there are plenty of lighter/more economical options out there which will perform very well.

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[Dude_with_the_tube]

for white solar it is irrelevant of is it an Acrho or ED or APO,all will show the same image quality wise.Obviously as longer the focal length as sturdier the mount has to be to avoid vibrations.

i use my 90mm F14.4 frac for white solar and i am getting nice 3D sort of image,i bet the same quality can be achieved with a much shorter and smaller aperture,but as i dont have any other,i just use this one

[A McEwan]

That's not quite the case, Gaidis. An achromat will still show false colour in white light viewing, while an APO will not.

The use of a Baader Solar Continuum filter will greatly reduce the CA when used with an achromat though, and will enhance the details very well too (regardless of whether it is used with Apo or achro).

Now if we were talking hydrogen-alpha, THEN it wouldn't matter whether an achro or Apo were being used as he wavelength is outside the white light spectrum anyway.

To add to previous replies, the ED80 does a great job on solar for me too (as well as the ED100), and has the advantage of being light to mount and quick to adjust to thermal equilibrium.

Ant

[Stu]

for white solar it is irrelevant of is it an Acrho or ED or APO,all will show the same image quality wise.Obviously as longer the focal length as sturdier the mount has to be to avoid vibrations.

i use my 90mm F14.4 frac for white solar and i am getting nice 3D sort of image,i bet the same quality can be achieved with a much shorter and smaller aperture,but as i dont have any other,i just use this one

Not sure I agree with that Dude. If you are looking at all frequencies then surely chromatic abberation will be an issue with a fast achro?

A long focal length achro or ed apo would give sharper results.

Of course, if you are using a narrowband filter like a continuum or are looking in Ha with a quark then CA is not an issue, although the figuring of the objective will be.

Stu

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[nightfisher]

I am playing about with this little Vixen vmc110 for solar white light, i was getting good results till it went all cloudy and misty 2 weeks ago !

[russ.will]

The same rules apply during they day as they do at night. It's white light, so you get CA. As this thread seems to be a gratuitous excuse for pictures of ones solar setup, here's mine:

[Stu]

Very nice Russ :-)

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