refractor for FULL Disk

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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fedele
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refractor for FULL Disk

Post by fedele »

Hi.

I have a Mewlon, a Mac 127, and i want to buy a refractor to binoview and imaging the full disk of the sun.
I want to Buy a Daystar COMBO with a TV Powermate 2,5 x

with these two refractors:

- TS ED80 f 7 fpl53
- Taka FC100 DZ

i will be able to wiew and image the full disk?

thanks


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MalVeauX
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Re: refractor for FULL Disk

Post by MalVeauX »

Hi,

Yes, you can easily image the full disc with a short refractor and a Quark Combo (with a 0.5x focal reducer after the Quark). The thing you need though is a large sensor (1 inch class, mono).

Note, there's zero benefit to FPL53 or Fluorite glass for sub-angstrom solar viewing, it's one wavelength of light, no color correction involved. So don't feel you need a high end refractor for this; you don't. An achromatic doublet is fine for this. Just get a good focuser. If you plan on using the scope for other things, like night time and terrestrial, then sure, get a high end scope if you please. Just be aware it doesn't add anything to sub-angstrom viewing/imaging at all.

The Quark Combo has about a 12mm blocking filter, so you can use up to 1,000mm focal length (technically 1,200 but lets just keep it simple for room to spare) and still see a full disc through it. You'll need to put a telecentric in front of it to perform right, the powermate is the cheaper way to get by, so it will work. You then use a focal-reducer (0.5x) after the Quark and it will bring the scale back down to something reasonable (if imaging). You want to get it to about F30 at the etalon to start. So you may want something around F10~15. An example would be to take a 120mm F8.3 achromatic doublet and have a quality 66mm mask made for it. This would take it to F15 naturally. Then a 2x powermate takes it to F30. Then your Quark combo. Then a 0.5x focal reducer. Then a large 1" sensor and you'll image a full disc. You can do it even easier with shorter scopes of course (but the apertures get small to maintain the F30 at the etalon needed). That's the benefit of the Combo version is to use larger options as you have freedom of what amplifier to use.

Overall, if your goal is full discs, don't get a rear mounted mica-spaced etalon from Daystar. Just get a Lunt. It's so much easier and higher quality to image a full disc with a Lunt and you don't need all that extra stuff going on. Likely to get a better quality etalon too.

Very best,


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