L'observatoire du Soleil. High Resolution Solar Observer

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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L'observatoire du Soleil. High Resolution Solar Observer

Post by Aerospace solutions »

Warmly greetings from sunny Moscow, dear rainbow-colleagues!)

I have been reading parchment Solarchat forum pages for so long, so I guess this resource would become my new home, where with the velvet of a candle burning in the night treatises on the contemplation of the Sun can reunite )

For the time being my solar collection of optical art works consists of Coronado Solarmax III BF15 and several PST - these are absolutely charming and bellissimo handcrafted instruments from Meade consortium for full disk solar observations. And since solar observation is my new passion I'm intend on supply my collection with a high resolution solar observing instrument what opens the path of variability for this solar quest to be accomplished.

There are several ways to achieve the desired goal - via classical concept or with a less dogmatic approach. I'm intend to be 65% visual/35% photo

1. As for traditional way these components were selected by me:

- iStar H-Alpha optimized doublet 150mm f/10 objective lenses
- customized tube with MoonLite focuser
- Solar Spectrum RG 18mm 0.3A H-a filter proudly made by Mark (18mm aperture mica etalon, 12 blocking filter)
- Baader D-ERF full aperture 160mm filter with cell
- Baader TZ-3 telecentric for for achieving f/30 focal lenght

It would be something like our Baikal astrophysical Observatory but with a bit less resolving power limited with Moscow seeing :)
http://ru.iszf.irk.ru/%D0%A2%D0%B5%D0%B ... B8_H%CE%B1

2. As I have already got in collection an absolutely brilliant 180mm f/15 Maksutov-Cassegrain from SkyWatcher due to low spherochromatism perfectly corrected for all visual waves of electromagnetic spectrum (blue, green, red) with 0.982 Strehl ratio both at 532/632nm, 1/8.6 Lambda optics quality, maybe there would be some reason of using this instrument for both solar visual/astrophotography works? This instrument could be little more superior than traditional 8" Shmidt-Cassegrain offers from AiryLab and Baader Tri-Brand concepts due to far less spherochromatism, less CO and longer focal lenght. So there would be:

- Maksutov-Cassegrain 180mm f/15
- Daystar Combo Quark (chromosphepe, for examle, see below) (21mm aperture mica etalon, 25 blocking filter)
- ERF full aperture filter from dear Valery or Baader
- Televue Powermate 2.5x that would provide me f/38, so with Daystar chromosphere Quark I would probably get 0.4-0.3A (somewhere it was declared that with small size etalons Powermate 2.5x would give the most delightfull result(?) please, confirm this)

There are some overall advantages going with classic refractor-variation:
+ Quicker thermostabilization (guess it won't be a big problem for 150mm doublet)
+ Probably a bit higher level of contrast vs MK 180 due to absense of CO

In contrast
+ It is only declared on site, that H-Alpha optimized doublet would have 0.98 Strehl ratio, in fact after our own interferometrical test on optical bench that value could be 0.93, 0.85 or - in worst case - even lower. You can only state about optics quality if you check it by yourself. So in case with MK 180 optics I have got 0.982 Strehl ratio which is already guaranteed. Initially MK has 2700 focal lengh vs 1500 focal lenght of iStar doublet
+ When seeing "allows" MK 180 would have a bit higher resolving power
+ due to low chromatic aberrations, low spherochromatism and guaranteed optical quality MK 180 would be a for more versatile instrument for nighttime observing - especially for planets - than ordinary 150mm achromatic doublet. In this case I guess it would be a good "all-in-one" solution both for high resolution solar and planets observations
+ in addition to everything else MK would be lighter and threefold more compact solution with "short moment of arm", so even mounted on AVX-class mount the hole setup would be stable enought to provide high-power solar observation experience
+ even equipped with Daystar Combo Quark, the refractor-variation would cost about 2000-2500$ more

There is always an option to stick with non seeing-addicted (if someone had "seeing world map"!) front-mounted etalon system, like 100mm Lunt etalon reunited with 100 f/13 Nothek refractor https://www.northek.it/language/en/prodotto/dp-100-2/ or for example double stacked Solarmax III 90mm...

So, what's on your mind, dear colleagues :seesaw - is 180mm Maksutov-Cassegrain worth it to give him a try as high resolution solar observing instrument? And what would be the best constant in terms of "size/angstom bandwidth" H-a rear mounted mica filter for this system? Сonsidering that I would always prefer quality vs field of view and I am going to use it in combination 65% visual/35% photo.

P.S. I've got two absolutely new PST-instruments, so there is always in option to make a self-construction system with MK including combination of two 30mm size etalons that would give chance of using my instrument as high resolution prominence viewer with 1.0A combined with 180mm aperture or 0.5A chromosphere telescope.

P.P.S. Since solar observation is my new passion, some general question if I might ask:

1) In the concept of solar observations what does rear mounted etalon's size affect? More parallel beam concentration, overall better contrast or just field of view?
3) What blocking filter would become as best solution considering 180mm aperture (rear mounted mica etalons usually have 12 blocking filter, except Daystar Combo Quark which has 25 blocking filter) ?
2) In terms of best possible quality which solution is better - Baader/Beloptic telecentric or TeleVue Powermate and why? Telecentric has two elements design while Powermate consists of four element, does the formula "the smaller the number of elements in optical path the better quality is" can be applied here?
3) Eyepieces :D Since, for example, Daystar has long term collaboration with TeleVue (like Qusetar-Brandon)... I wounder if there are some different points of view considering of choosing best eyepieces for H-a observing? There are special optimized for H-Alpha solutions like Coronado Cemax, Lunt and Daystar 25mm "ortho" (has anybody any experience with it?) What about japanese ortho? P.S. Tommorow I'm going to compare Cemax vs Brandon with my Solormax III 70mm.

Dear colleagues, I will very appreciate your collaboration of thoughts and experienced points of view :band2 )
Attachments
PST.jpg
PST.jpg (598.55 KiB) Viewed 1923 times
MK interferometric test.jpg
MK interferometric test.jpg (150.79 KiB) Viewed 1923 times
Solarmax III.jpg
Solarmax III.jpg (378.44 KiB) Viewed 1923 times


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Montana »

A very warm and sunny welcome :hamster: :hamster: I am sure someone will be answer some of your questions. It looks like you have a lovely couple of Coronado telescopes, but we always have aperture fever :) I look forward to seeing some images from them or some observations.

Alexandra


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Highbury Mark »

Welcome to the site! I view via a relatively modest 70mm double stack system so will leave your technical questions to those far more qualified to do so. I’ll be interested to see how a 180mm Maksutov is rated for solar ha - I’ve had several catadioptric telescopes and the Mak I had was certainly the sharpest.
One thing I can comment on is eyepieces for solar ha. I’ve tested many different eps over the years, and am currently tracking down a pair of excellent Carl Zeiss microscope EPs for use with my binoviewers, but broadly I’d my favourites are:
Pentax XF zoom 6.5-19.5mm; TeleVue Plossls (32mm, 20mm, 15mm, 11mm); Leica ASPH zoom; TV Panoptic 24mm; TV Delite 18.2mm.
Just below this level are Fujiyama orthos, Meade Plossls, Nagler T6


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Aerospace solutions »

It'a a pleasure to me wishing a sunny day to those who is fond of contemplating the fusion reactions of our Star!

Yes, I am absolutely inspired by the idea of using this ultimate compact 7" MK as a high resolution solar observing instrument - an exceptionally rare and inexpensive concept that could bring a pleasant experience, with high potential of being versatile telescope both for night&day observations. As for bellissimo Coronado instruments collection :) - in the concept of aesthetic perception these are among most charming instruments I've ever saw, real state-of-art, unlike large-aperture SCT they always have a festive look )

If I might I also would like ask some interesting questions born in the subconscious:

About eyepieces
- in concept of solar observing has anyone tried simple (three elements design) eyepieces in rear-mounted mica etalon long-focal systems like Edmund RKE or TMB Monocentric?
- does anybody have any experience with Russ Lederman's Binotron and his patented LOA-design eyepieces? Or maybe someone has tried stereo effect solar observing with new William Optics Pegasus binoscope?

As for other variations of high resolution (and exclusively rare) solar observing telescopes:
- what would be your opinion considering DK-line telescopes of Parallax instruments? Might have some interest in one of these, maybe someone living in USA has information about if Joe still produce them and since F.R. doesn't make optics does anymore know what was the optics supplier selected by Joe? http://www.parallaxinstruments.com/cass ... grainspec2
- and about concept of highly-customized prof. Cassegrain from Ludes https://www.apm-telescopes.de/en/telesc ... pe-12.html Being customized as 305mm 8000 focal lengh (f/26.2!) telescope that might be very intersting high resolution solar observing machine without any need of telecentric system involved in optical path ....


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Highbury Mark »

Hi - I’m sure the best three element EPs would be exceptional for solar! But I found that Fujiyama orthos were beaten by TV Plossls on my scope (Very close in performance so only talking slight difference. TV Plossls have unbeatable transmission though). Also like TAL super Plossls and some of the Meades.
One regular contributor to this forum - Deepsolar64 - has a pair of RKE 28mm, so he might give an opinion about how they perform for solar ha.
In general, simpler eyepieces tend to work the best, though I find more complex widefields work well in binoviewers.


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Bob Yoesle »

Hmmm...

What sounds good in theory often does not work out well in reality. This is especially true of daytime solar observation versus nighttime observations. I generally don't have enough good daytime seeing to effectively use over ~ 150 x, and usually half that is my sweet spot. The other item is having a good understanding of the limitations imposed by the optical system on the performance of the etalon used.

The first thing to ask yourself about all these larger instrument choices is will your local seeing support the long effective focal lengths your proposed systems result in?

For example, the Istar 150 f/10 will have an EFL of 4.5 meters at f30. The Cassegrains likely will be even larger in EFL when used at f 30. If you're 65% visual you'll need longer FL eyepieces - the TeleVue Nagler 31 mm and 50 mm Plossl come to mind. Or consider a focal reducer prior to the eyepiece to get reasonable magnification(s) - but here the quality will of course need to be addressed for the intended purpose (visual vs. imaging). Most of the eyepieces you've mentioned will yield far too great a magnification for practical use. You'll end up still using your existing Coronado scopes for visual and the larger scope mostly for imaging - when seeing permits.

The Cassegrains will generally need a full-aperture ERF to keep the secondary mirror and support from getting overheated. You're probably better off with the Baader or AiryLabs SCT's with an ERF coated corrector plate.

An important point about these instruments is not spherochromatic aberration, it is field angle magnification. The Cassegrain's secondary mirror acts as a Barlow lens and magnifies the field angles, and the PowerMates or telecentrics will generally not be optimized for this - perhaps Oliver at BelOptik can design a custom telecentric for the particular telescope you chose. The PST or other air-spced etalons will be more affected by magnified field angles than the solid spaced etalons - but in either case you're talking small Jacquinot spot diameters and only high-res narrow-field imaging, and even less suitable viewing. Again, will your local seeing support this?

For many and perhaps most people the answer is no unless you're located near an ocean or on a very good mountain top - or both...


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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by Valery »

Equipment solutions depends of:

1. Desired results
2. Budget for solar equipment
3. Time availability for solar observing
4. Observing conditions
5. Dedication to solar observing/imaging and perseverance

говорите по-русски?

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Re: L'observatoire du Soleil. High Resolution Solar Observer

Post by DeepSolar64 »

Welcome!
I am certainly familiar with Coronado since I have both a SolarMax II 60 and SolarMax II 90. I bet that SolarMax III 70 does quite well. As far as eyepieces go for solar I usually use the Cemax and Lunt eyepieces. Both do quite well. I also use a TeleVue 20mm plossl quite a bit. It does well also. I do have two 28mm Edmund RKE eyepieces. Wearing glasses means their adequate eye relief is a big plus. I use the RKE eyepieces a lot. Both for night and day observing. Recently I tried a friend's set of TeleVue Delos eyepieces, mainly on his TV85 refractor set up for white light observing. The Delos excelled at that and I had really good seeing that day. The Delos-TV 85 combination showed the individual granules better than what I would have thought possible in an 85mm scope. I plan to buy a set of either Delos or DeLite eyepieces in the near future. The Lunt zoom is on my list also.

Welcome to SolarChat!

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