Opinions on a suitable new Achromatic frac for solar

[Mark at Beaufort]

Okay I would like some opinions especially any member that has used an Achromatic refractor for solar work.  I know somebody is going to advise that I should purchase an ED or APO but I don't want that expenditure at the moment. I would add that I did own a 4" Astro Tech ED frac which I used with a Lunt HW, Baader Continuum filter and binoviewers which was brilliant - so I know what is possible with the right equipment.

My good friend @Stuhas given me some useful advice already saying "a well corrected achro like a TAL 100 or better one of the 102 f11s would work well for solar with a Herschel Wedge. It is often the spherical aberration that kills the detail in fast achros, and that should be well corrected in these scopes."

I might be lucky finding a TAL 100 but I think that a f/11 might not be suitable on my AZ5 although it has the better tripod and pillar and the literature states a 9kgs carrying weight - maybe!!

Anyway I have looked at these OTAs - has anyone had one and used it successfully mainly for Solar White Light observing.

https://www.firstlightoptics.com/bresser-telescopes/bresser-messier-ar-102l-1000-refractor-ota.html

https://www.firstlightoptics.com/evostar/skywatcher-evostar-120-ota.html

http://www.opticstar.com/Run/Astronomy/Astro-Telescopes-Opticstar.asp?p=0_10_1_1_65

If you think I should stay with my Skywatcher 150P Newt + solar filter and wait for a suitable 100mm ED frac then I don't mind if that is what you want to tell me.

 

[mikeDnight]

My immediate thoughts ran to an early Tal refractor or, perhapse a Vixen F10 or F13 achro. I'm not sure about the later Tal's as I seem to remember they have a plastic lens cell. Lyra did a nice 102 F11,  and Antares made a very nice 105mm F14, but an AZ5 might have to somehow turn into a EQ5 or Vixen GP.

There is also a new 80mm achromat sold by Takahashi which comes with what appears to be a nice altazimuth mount. But for the price you could get a Second hand SW102ED.

Edited April 10, 2020 by mikeDnight

[Alan White]

Hi Mark, hope you are OK.

I have used 2 differing 80mm Achro's for WL Solar and they were ok, even the f9 one.
Purchased the 103ED Vixen and quite different and more detailed view with all the kit the same shown.
It astonished me at the marked change in quality.
 

[johninderby]

Something else to throw into the mix. Should be excellent for WL.

https://www.teleskop-express.de/shop/product_info.php/info/p11262_TS-Optics-102-mm-f-11-ED-Refractor-with-2-5--RAP-Focuser.html

BTW the new Takahashi isn’t actually made by them. Made by another company to Taks design.

Edited April 10, 2020 by johninderby

[JeremyS]

1 hour ago, mikeDnight said:

My immediate thoughts ran to an early Tal refractor or, perhapse a Vixen F10 or F13 achro. I'm not sure about the later Tal's as I seem to remember they have a plastic lens cell. Lyra did a nice 102 F11,  and Antares made a very nice 105mm F14, but an AZ5 might have to somehow turn into a EQ5 or Vixen GP.

There is also a new 80mm achromat sold by Takahashi which comes with what appears to be a nice altazimuth mount. But for the price you could get a Second hand SW102ED.

I assume that’s a typo, Mike. You of course meant Tak not Tal

🙂

 

[vlaiv]

I have SW Evostar 4" F/10 and have used it (only once so far) for white light solar with Lunt Herschel wedge (1.25") and Baader solar continuum filter.

I have to say - I was not pleased with it. I'm 99% certain that view was poor due to seeing. I was able to see some faculae, but nothing more (of course it was quiet time and no spots), but friend of mine - first time viewing - could not see them. Other than that - such a long scope on AZ4 mount is not what I would call rock solid.

Will need to test this combination further in better seeing and when some sun spots arrive ....

[Mark at Beaufort]

54 minutes ago, vlaiv said:

I have SW Evostar 4" F/10 and have used it (only once so far) for white light solar with Lunt Herschel wedge (1.25") and Baader solar continuum filter.

I have to say - I was not pleased with it. I'm 99% certain that view was poor due to seeing. I was able to see some faculae, but nothing more (of course it was quiet time and no spots), but friend of mine - first time viewing - could not see them. Other than that - such a long scope on AZ4 mount is not what I would call rock solid.

Will need to test this combination further in better seeing and when some sun spots arrive ....

Thanks for that - this is what worries me about buying an achromatic  refractor especially as I had previous used a quality ED frac.

[Mark at Beaufort]

Reading these replies it confirms that I really need to consider an ED frac. Unfortunately I also need to budget for a 2" diagonal + 1.25" Lunt HW. I have all the available finderscopes + EPs. Its frustrating in hindsight that I had a 1.25" Lunt HW + a 2" TeleVue Everbrite diagonal but we all make mistakes in selling kit that we regret.

[Alan White]

11 minutes ago, Mark at Beaufort said:

...we all make mistakes in selling kit that we regret.

Indeed we do, indeed we do.
Sadly part of the Astro journey Experience and gaining our Astro Wisdom.

[John]

The ED doublets I've owned and used have all been a step up from achromatic doublets, obviously in terms of CA control but also in terms of SA correction and therefore high power definition.

It seems to me that when the more expensive glass is used the manufacturers take a little more care with figuring and polishing.

 

[johninderby]

One thing I highly recommend is getting is a solar filter for your 9x50 finder. Much better than the SolSearcher type and makes it much easier to get the sun centred. 

[Mark at Beaufort]

27 minutes ago, johninderby said:

One thing I highly recommend is getting is a solar filter for your 9x50 finder. Much better than the SolSearcher type and makes it much easier to get the sun centred. 

Thanks John - to be honest I bought a Svbony solar finder which is spot on. I use it on the Skywatcher 150P with the 13mm Ethos and the image of the Sun is in the centre of the OTA. But thanks for the thought.

[Louis D]

I used my 20 year old ST80 and Baader Solar Film for viewing the 2017 eclipse's partial phases and, with the filter off, during totality.  I also took it to work and set it up in the parking lot to glimpse the recent Mercury transit between passing clouds.  It worked just fine for both, and I didn't notice any CA or SA, but I wasn't pushing the power above 50x, either.

[johninderby]

3 minutes ago, Mark at Beaufort said:

Thanks John - to be honest I bought a Svbony solar finder which is spot on. I use it on the Skywatcher 150P with the 13mm Ethos and the image of the Sun is in the centre of the OTA. But thanks for the thought.

I have a Svbony solar finder in the drawer. I use the 9x50 finder to check the sun to see if it’s worth getting the scope setup as the image is big enough to see if there are spots. Well if there were spots to see. 😁