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Help with solar telescope assembly

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#1 hermanj

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Posted 16 June 2022 - 11:20 AM

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

 


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#2 DHurst

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Posted 16 June 2022 - 12:24 PM

I say keep it simple:

https://luntsolarsys...scopes-can-do/ 


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#3 HubSky

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Posted 16 June 2022 - 12:27 PM

Should probably post this question in the solar imaging and observing forum. 



#4 hermanj

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Posted 16 June 2022 - 01:44 PM

Thanks for the replies. I have considered the Lunt, but I like to fiddle with things myself and would get greater satisfaction with assembly as described in my post. If you consider appropriate, I would like to ask an @admin or @moderator to move this thread to solar forum please.



#5 vincentv

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Posted 16 June 2022 - 07:37 PM

 

1) Is a SCT the way to go? Am I better off using a Dobsonian or some refractor?

Refractors are prefered, SCT is workable, newts can be a pain for h-alpha. 6" is considered large for solar. Before investing serious money get a baader film filter for the SCT and make sure you can view at the expected magnifications. Daytime seeing can be very different from nighttime seeing.

 

 

3) Do I need an additional blocking filter for the above setup? Which would be a good choice?

The quark has a built in blocking filter.

 

 

6) Will I be able to observe full sun disc with such a setup and Quarks limited aperture?

Not even close. Let's see, the 6" sct + 3x telecentric gives an effective focal length of ~4500mm. The quark's clear aperture is 21mm (roughly matches a 25mm plossl's field stop).

A quick online search says: (eyepiece field stop) / (focal length) * 57.2958 = (TFoV in degrees)
(21 / 4500) * 57.2958 = 0.27 degrees. That's about half the sun.

With the regular quark and its 4.3x multiplier you need to stay below ~500mm to achieve a full disk.


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#6 Napp

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Posted 16 June 2022 - 07:42 PM

An SCT is not a great way to go with a quark.  Refractors are better.  SCT's require an expensive energy rejection filter (ERF) for a Quark.  Only big refractors need an ERF.  6 inches is too much aperture for solar anyway.  Seeing will not be good enough to take advantage of it.  You only need a doublet refractor for hydrogen alpha solar because you are basically working with one wavelength of light.

 

Personally, I would prefer to have the manufacturer do as much as possible and I not have to customize too much.  Why unnecessarily complicate things.  You will have enough challenges with solar without adding to it.  Instead of a 6 inch SCT I'd recommend a 127mm refractor.  


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#7 MalVeauX

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Posted 16 June 2022 - 08:02 PM

Dear solar observers,

 

I have been reading this forum for a while, but this is my first post. Please, be gentle smile.gif .
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.

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#8 hermanj

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Posted 19 June 2022 - 02:56 AM

Thank you for all the in-depth answers. Exactly the help and advice I have been looking for! I am currentyl quite busy, so it will take ma a few days to process all the info in the responses. After that, I am sure I'll be back with some more questions :)

WIsh you all a nice day!



#9 hermanj

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Posted 06 July 2022 - 11:27 AM

So I have considered your feedback and I think I'll go with the Lunt LS80MT. I still have some questions though, so please help me out if you can.

 

1. is the internal DS worth it* Are there serious problems with the reflections. Again, I'm primarily interested in viewing.

2. How effective is Lunts HRG filte rin reducing the reflections? How much does it decrease the image brightness? Am I bette roff using a custom installed circular polarizer?

3. I want to keep an option of adding imaging capabilities later on. I think flip mirror diagonal is a good option for this, but do I need to order the straight through blocking filter in this case? Is the straight through BF still usable for viewing with star/flip diagonal because of the added optical length? I plan on using binoviewers.

4. Any opinion on the stock R&P focuser on this scope? Is the FeatherTouch option a significant upgrade?

5. I am also looking for recommendations for mount and dovetail for this scope. Poratbility is quite high on the list here (not too heavy and bulky, maybe integrated battery, etc.).

 

Thanks for help and have a sunny day!



#10 MalVeauX

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Posted 06 July 2022 - 12:53 PM

Hi,

 

Yes the internal DS is worth it. The clear aperture is very big and the entire disc will be within the sweet spot, even double stacked. It's the best commercial instrument in its aperture range for cost. Especially awesome for visual because of the real time pressure tuning and no waiting time and no electronics. There are not serious problems with reflections. Lunt will set you up with how that is handled when you buy it all. Just call or email them and they will have it set for you no problem.

 

It works fine. You can certainly use your own. But Lunt could set this up in advance for you.

 

You don't need a flip diagonal nor a straight through. This instrument with a diagonal blocking filter is ready for imaging with no additional things added. Just plug in a camera. It's that simple. Get the 12mm or 18mm blocking filter if you are using binoviewers and want to use larger imaging sensors. No other things needed. It's an imaging class instrument without any extras. It's also an excellent visual instrument. Truly one of the best do-all scopes you can get for solar.

 

They're both excellent. If you're super touchy with focusers, maybe go feather touch. I find the stock crayfords/rackpinions to be completely fine even for my imaging let alone visual.

 

For the mount, it depends on how portable (weight) and fussy (setup) you want it to be, such as an EQ drive, a newer Harmonic drive, or an AltAz drive mount. Hands down the most simple mount I would suggest would be something like the iOptron AZ Pro. Yes, its Alt Az but that's no big deal at all even for imaging. For a super portable harmonic drive, ZWO's AM5 is pretty solid and simplified for what it does. All EQ mounts with counter weights will be more fussy to setup (polar alignment, weights, shaft, etc). For portability and simplicity something like the iOptron AZ Pro would be solid. It's a dual saddle so you could setup two scopes on it. No counter weights to fuss with. No alignment. Just 1 point align on the sun itself and you're set. Internal battery.

 

Very best,


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#11 melllince

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Posted 07 July 2022 - 02:37 AM

So I have considered your feedback and I think I'll go with the Lunt LS80MT. I still have some questions though, so please help me out if you can.

 

1. is the internal DS worth it* Are there serious problems with the reflections. Again, I'm primarily interested in viewing.

2. How effective is Lunts HRG filte rin reducing the reflections? How much does it decrease the image brightness? Am I bette roff using a custom installed circular polarizer?

3. I want to keep an option of adding imaging capabilities later on. I think flip mirror diagonal is a good option for this, but do I need to order the straight through blocking filter in this case? Is the straight through BF still usable for viewing with star/flip diagonal because of the added optical length? I plan on using binoviewers.

4. Any opinion on the stock R&P focuser on this scope? Is the FeatherTouch option a significant upgrade?

5. I am also looking for recommendations for mount and dovetail for this scope. Poratbility is quite high on the list here (not too heavy and bulky, maybe integrated battery, etc.).

 

Thanks for help and have a sunny day!

I have the 80MT-DS for nearly two years, Based on my experience, the HRG can notably reduce the reflection between two stacks.

My suggest is asking Lunt for binoviewer's best match. Mine focuser is FT, it's good.

The Sky-watcher has a SolarQuest mount, they add a camera to the AZ-GTi mount, that make it can track the sun disk, exactly fit your need. The 80MT-DS on the very edge of it's weight Capacity, but it can work.

The 80MT-DS's original dovetail is too short to balance the back-heavy scope. I change it to a 10" dovetail.


Edited by melllince, 07 July 2022 - 03:19 AM.


#12 chemman

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Posted 09 July 2022 - 02:01 AM

So I had to step it up a notch, I have the LS100MT,  double stacked of course with the BF3400.   Cost a fortune but I had made arrangements for that.  It is a great piece of gear, I absolutly love the thing.  Just today ran the rig as a single stack, checked out precisely where the pressure in the etalon produced the best tuned image, using a 27mm eyepiece.  Then I put on a ASI1600MM camera and scanned the entire available field of view recording what I saw.  Definitly produced a sweet spot much larger than the native image size, likely double in horizontal and vertical. I added the second etalon and pressured up to see the entire surface of the sun POP with activity, spectacular it was.  I have to say I have no regrets what so ever getting the 100.   Less than a minute and I was imaging the daytime Moon, great views of it.  Switched to binoculars and invited the neighbors over, they were impressed.  Imaged using the ASI1600MM with a filter wheel for the next few hours.  

 

Just to let how it is if you dive directly into the deep end of Solar/night viewing.

 

Chuck


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#13 hermanj

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Posted 10 July 2022 - 04:41 AM

Thanks to everyone for responding! I'm sure I'll love my Lunt as well :). To be honest I have never looked through a solar telescope and can hardly wait to do it through my own piece of gear.

 

Some further questions:

1. Lunt suggested me to use their zoom eyepieces with the binoviewer, but I can not find that they have clickstop, which I think is a great minus for binoviewing. Would you recommend any eyepiece for binoviewing? The only ones I could find that have the clickstop are the Baader Hyperion zoom Mark IV. I have also considered the Pentax XF, but could not find any details about clickstop. Any special negatives/positives to the Baaders?

 

2. This one is for mellince or anyone with experience with Skywatcher Solar-Quest. Does it reatin all the night time functionality of the AZ-GTi? Also, have you tried it with the LS80MT, since it is at the edge of payload capacity?

 

Thanks again to everyone!



#14 bigdob24

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Posted 10 July 2022 - 07:23 AM

1. Lunt suggested me to use their zoom eyepieces with the binoviewer, but I can not find that they have clickstop, which I think is a great minus for binoviewing. Would you recommend any eyepiece for binoviewing? The only ones I could find that have the clickstop are the Baader Hyperion zoom Mark IV. I have also considered the Pentax XF, but could not find any details about clickstop. Any special negatives/positives to the Baaders
 

I find the Baader 8/24 do a great job with allowing  the right magnification for conditions.

Of coarse with the Denks you have to have the OCS at an additional cost to bring the binos to focus.

‘I’ve found the click stops to be useless as on my set they aren’t really positive , just use the reference mark , never a problem.
Binos are the way to observe .

 



#15 melllince

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Posted 10 July 2022 - 08:07 AM

Thanks to everyone for responding! I'm sure I'll love my Lunt as well smile.gif. To be honest I have never looked through a solar telescope and can hardly wait to do it through my own piece of gear.

 

Some further questions:

1. Lunt suggested me to use their zoom eyepieces with the binoviewer, but I can not find that they have clickstop, which I think is a great minus for binoviewing. Would you recommend any eyepiece for binoviewing? The only ones I could find that have the clickstop are the Baader Hyperion zoom Mark IV. I have also considered the Pentax XF, but could not find any details about clickstop. Any special negatives/positives to the Baaders?

 

2. This one is for mellince or anyone with experience with Skywatcher Solar-Quest. Does it reatin all the night time functionality of the AZ-GTi? Also, have you tried it with the LS80MT, since it is at the edge of payload capacity?

 

Thanks again to everyone!

In mount forum there are some topic about the SolarQuest. You can PM those who own it.



#16 Astrojensen

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Posted 10 July 2022 - 08:47 AM

  6 inches is too much aperture for solar anyway.  Seeing will not be good enough to take advantage of it. 

I hear this all the darn time, and it's driving me nuts. IT IS NOT TRUE! Or, at least, it highly depends on where you live. From my location, the seeing IS occasionally (not every day) good enough to use a 6" at full aperture and get all the resolution from it. 

 

And when that happens, the views are so shockingly outstanding, it's worth all the other days, where you're limited to lower magnifications. A friend is using an 8", and has the same experience. 

 

But even at lower magnifications, the big aperture is a considerable advantage, because it delivers very bright, sharp, high-contrast views, that blows smaller apertures out of the water. I have never seen a small, dedicated solar telescope show as much detail in prominences, as my APM 152ED and Quark will deliver. Everything 100mm and smaller can't hold a candle to it. It isn't even close.  

 

Now, disk details are lower contrast than a double stacked solar scope, but it is as good, or better, as a single stacked one. 

 

And before I tried the Quark on the 6" APM, I, too, used to think that the daytime seeing was never good enough to support using a 6". Oh, how wrong I was. Since then, I have enjoyed some of my finest, most memorable observing experiences in my entire 30-year amateur astronomy career, with the Quark on the 6" APM. 

 

Aperture wins, even on the Sun. 

 

 

Clear skies!

Thomas, Denmark  


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