Dear solar observers,
I have been reading this forum for a while, but this is my first post. Please, be gentle 
.
I am seeking your help with assembling together my first solar telescope. A short background: I am technology and nature enthusiast with a few years of experience in work in research and now some work in development engineering. I have always been interested in space and have also worked for three years on a rocket engine development project. I have some basic knowledge about optics from photography, but no practical experience in astronomic observation and the required hardware. This year I received an unexpected birthday present, where my loved ones will buy me a solar telescope of my choice. I read through quite some posts on this and other related forums, but I am still having problems understanding certain components and their function. This is why I am seeking your help and advice.
I am looking into an option, that would also allow me night time observation in the same package (I am limited in storage space) and at the same time be quite portable. I have access to decent to good viewing conditions, since I have accessible hills nearby (1500m above sea). My primary interest is viewing, with probable upgrade to imaging some time later. So my idea is to buy a 6'' SC and equip it with solar filters.
This is the current setup I have in mind:
- 6'' SCT Celestron Nexstar Evolution 6 + equatorial wedge
- Baader 160mm D-ERF (i will 3D print the cell myself)
- Quark Combo Chromosphere Ha filter
- Maxbright 2 binowiewer
- 1,25'' star diagonal
- 3x 1,25'' telecentric (for Quark Combo)
- basic assortment of oculars (suggestions please!)
- Feathertouch focuser (if budget survives it...)
These are my main questions so far:
1) Is a SCT the way to go? Am I better off using a Dobsonian or some refractor?
2) Would you suggest to use Quark Combo + telecentric or the normal Quark with integrated collimator? Why?
3) Do I need an additional blocking filter for the above setup? Which would be a good choice?
4) Are zoom oculars usable on a binoviewer?
5) What kind of fixed oculars offers the best price/performance for a setup like this? (mostly solar, moon and planetary viewing)
6) Will I be able to observe full sun disc with such a setup and Quarks limited aperture?
I am sure I will have some further questions, but if anyone can help me out with these, it will be a great start. I also hope I put the topic into the correct forum.
Wish you a sunny day,
Jošt
Hi,
1) SCT is not optimal, it's doable, and is the 2nd easiest commercial scope design to adapt to solar well while still being good for non-solar. That said, it will work and is one of the most compact larger aperture systems if you need this to be greatly portable. Personally I would advise you to focus on a 4 inch refractor for solar as a "do all" instrument, as long of a focal-ratio as you can happily deal with or mount. The 102mm F7 variety with good focusers would be an excellent way to go. No need for super expensive DERF on a refractor. Using a mirror based optic puts you on a big DERF fast and that's just not economical for such an entry filter like a Quark in my opinion when a refractor can do this for way less and keep it more simple without fear of a costly DERF getting broken transporting around, or even getting one in the first place.
2) If buying a Quark, I would go combo + telecentric. You get more control and you get a larger blocking filter. Ultimately its just more versatile with what can be done with it long term. That said, I would highly suggest you consider other options too, don't get too comfortable on a Quark with a big aperture mirror based instrument and DERF so quickly. My reasons: 1) etalon quality and 2) seeing limitations.
3) A Quark has a built in blocking filter, so no. The standard one is 12mm, the combo version has a 25mm blocking filter.
4) Yes, Baader's click stop version is ideal so they're the same actual focal length.
5) Simple eyepieces are best here, not the fancy huge AFOV ones, to have max contrast. Televue Plossls are highly prized for this purpose. If you use a long effective focal length system, you will want long focal length eyepieces (32mm, 25mm, etc).
6) You will be able to view a full solar disc, with a Quark, with a short instrument (400mm or less focal length) with a standard Quark (with built in 4.2x telecentric). With a Combo Quark, you can get away with a longer focal length instrument (but still use a telecentric, example, a 2x telecentric and a meter or less focal length, since the blocking filter is larger, you can get a full disc with longer focal lengths). Overall a Quark needs two scopes to do good full discs and good moderate/high res views at partial disc FOV. It's not a "do all" filter with one scope.
You should take some time and explore what all options you have. For example, do you want something that requires electronics to work all the time, requiring a battery and requiring time to temperature tune? Or do you want something that doesn't need any of that and tunes instantly and requires no electronics and has no points of failure other than coatings and physical damage? Do you want this to be a long term thing or just something to play with for 1~5 years or maybe up to 10 years? Do you care about quality vs quantity?
You should also evaluate what you value the most, from visual to imaging in the future, in terms of your imaging experience and what your goals are there. You should definitely evaluate portability if you need it and what your mount will be, etc.
And you should evaluate your seeing conditions before you spring on any big aperture system.
Bare Bones Setup You've Described:
Baader 160mm DERF - $1400
3D printed cell/holder - $XX (insignificant)
Quark (standard) - $1300
C6 SCT - $550 (forget the evolution and all that initially)
$3300 roughly give or take, no mount, single etalon
If combo version, add another $350 for a Powermate/Telecentric
Add 70mm F6 or 80mm F5 refractor for full discs: $150~300
$4k, and over $4k basically and this is a very budget class system, the etalon quality is a gamble here, single stack, very seeing limited
For a portable visual and/or imaging mica-spaced filter option, as budget as I would go at this stage, would be something like:
102mm F7~11 refractor with excellent 2" focuser (ED has no value for this, so achromatic doublet is fine) ($300~500)
50mm (2") internal sub-aperture DERF (UV/IR block, Red, or HA 35nm imaging class filters as DERF) ($100~250)
Quark Combo + 4x Televue Powermate ($1300 + $350)
Binos + Eyepieces
~$2500 depending on congif, same budget class, still seeing limited
Upgrade etalon quality would be: Solar Spectrum etalon instead of Daystar (Add $1k~2k)
Vs
Dedicated / Multi-purpose setup, such as Lunt or SolarScope (I would not count SolarMax/Coronado at this point at all frankly)
Aperture 50mm to 80mm range ($1.5k to $4.5k)
Either way, add a herschel wedge of any brand for photosphere viewing (while film does this well too cheaper, a wedge is a lifetime purchase and will outlast you)
Having done all of the above, and bigger, 8 inch DERF and all the things.... If I had to choose one instrument for visual and imaging for life it would be a Lunt 80 modular scope with wedge. Simple. Best quality you're gonna get commercially on the first purchase. Can be upgraded/expanded/double-stacked. Full disc and moderate resolution views. No fooling around with electronics, filters, extra bits, etc. Image full disc and moderate resolution no problem with one instrument. Same instrument is a really good ED doublet (FPL53) with great focuser for non-solar use. This would be my ideal $4k option all day, every day for "do all" solar.
Very best,
Edited by MalVeauX, 16 June 2022 - 08:36 PM.
