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Seeking a Grab and go solar refractor

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#1 Jan.H

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Posted 10 August 2018 - 05:10 AM

Hi 

 

I am looking for a grab and go refractor, as a supplement to my APM 152 ED, my first telescope. I have used my APM 6" a lot with my Daystar Quark, and even though I only use 20 minutes to set it all up, it is still a lot off work if you only what a quick gaze at the sun. So I have been looking for a refractor which mainly will be used for solar observations, and I have found one , a Sky-Watcher Esprit 80 ED PRO Triplet with a 400mm focal Length. Does anyone, have any experience with this  refractor in regard to solar observing? I am still new to this discipline and my experience is still very limited, so what is your thoughts.? Your opinion is definitely appreciated.

 

Thanks

Jan H. =)

 

my current setup

 

 

 

 

 

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#2 sushi1128

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Posted 10 August 2018 - 05:35 AM

for grab ang go, a lighter and cheaper achromatic refractor will be great for your Quark. The narrow band pass of your filter will eliminate chromatic aberrations.  a ST80 with a moonlight focuser would be equal to the task . Or, you can get a Lunt Engineering 80mm ED OTA (ED but cheaper than the Esprit).  cheers

https://optcorp.com/...-ed-doublet-ota


Edited by sushi1128, 10 August 2018 - 06:09 AM.


#3 PETER DREW

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Posted 10 August 2018 - 06:28 AM

I would consider a dedicated Ha solar telescope like a 50mm/60mm Lunt for grab and go use, this presumes you wish to dispense with the Quark setup for quick sessions.

#4 junomike

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Posted 10 August 2018 - 07:11 AM

A smaller mount might be far more desirable over a smaller OTA.

If an Alt/Az can handle the AP task, that would be my choice!



#5 fcathell

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Posted 10 August 2018 - 09:13 AM

Check this out:  https://www.cloudyni...a/#entry8760029

 

FC



#6 MalVeauX

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Posted 10 August 2018 - 10:28 AM

Hello,

 

I would argue that if you want a dedicated solar scope, don't bother with a triplet APO as you're spending funds on color correction (and some very slight increases in general quality) that won't matter, and you're simply adding a lot of weight to the overall grab & go system without gaining much of anything, especially for visual. A doublet achromatic refractor will do essentially the same job for a lot less cost and a lot less weight. Use the saved funds to then get the most aperture hydrogen alpha filtration system you can afford instead as that's far more important. Now, that's not to say you will not benefit from a better telescope in general such as better machining, better quality focuser, better optical figures, etc. Just stressing that color correction optics don't do anything for narrowband at this tight of a bandpass (you're filter out all those wavelengths!) and you're just adding cost & weight by looking at triplets. So, if this is just for solar, I'd so go with a doublet APO at the most. Otherwise, a doublet achromatic is going to do virtually the same thing. If you plan to use it for more than solar, such as night time use, then by all means, get the better scope(s) if they're in your budget.

 

If you plan to continue using your Quark for this, a 400mm focal length will provide a full disc FOV with a 25mm eyepiece.

 

Visual with a Quark in general is often very much more about higher magnification views and you benefit from being able to use larger apertures. If you're really into full disc FOV viewing, it will be very important to keep the focal length short (400mm).

 

That said, it's very, very important to look at the focal-ratio with the Quark. The Quark really likes to work with a F30 light cone. If you get a really fast focal-ratio instrument, you may find the view is very bright, but also not very contrasty on the surface (proms will be fine either way). If you want to look at surface features you will need to try and keep that focal-ratio slower, to achieve F30 (or even longer!) with the Quark. I've tested it with an F5 instrument and then stopped it down to F10, making for F21 vs F43 and the difference was significant in terms of seeing surface features. This assumes you've dark adapted your eyes under a shroud (I know this is odd, but a realty of visual even for solar) and that you're tuned on band for the surface (which will also show proms perfectly fine by the way; thus I tune my Quark for the surface only, proms come through regardless). This mean that whatever scope you choose, you may want to consider stopping down the aperture to something along the lines of F6.5~F7.5 This is going to give you something much closer to F30 on those instruments. And something F8 to F10 is going to be even better for surface contrast.

 

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Some scopes to look at:

 

https://www.teleskop...rd-focuser.html

https://www.teleskop...rd-focuser.html

https://www.teleskop...-Telescope.html

https://www.teleskop...-opt--tube.html

(Just upgrade the focuser on this one, it's the same as an ST80, rebranded, put a 2" GSO focuser on it or equivalent and you're set for cheap)

 

I also highly recommend a sun blocker. You can get them pre-fabricated, or make your own. But they help you to keep your vision adapted and to keep you from glancing at the sun and from getting too hot!

 

http://www.scopestuff.com/ss_psl6.htm

 

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I used to use a PST for true "grab & go" solar. It worked. But, it was also a very tiny scale, so it was mostly a blank disc with some proms on the limb. But, it at least worked, was light weight and inexpensive. But the view was not something I would call blowing anyone away. It was also too difficult to do things with like binoviewers and stuff. I wanted more modular approaches. So I sold my PST eventually. Great starter scope, but I needed more and stayed with the Quark. The Quark on a short scope is a vastly better visual experience, and crazy better for imaging, even though its still considered an entry tier filter.

 

For my grab & go solar, I actually use a humble old Orion ST80 (400mm F5 doublet). I mask it to 60mm (F6.667) or to 40mm (F10) when using the Quark. I can't tell the difference in ultranarrow band between it and my 80mm APO, even when imaging. So I just use the inexpensive achromat for this. I upgraded the focuser to a 2" GSO to handle the weight of the Quark, plus I image with it. It's small and light and works on a small and light weight alt-az mount for true grab & go. I start with a 25mm eyepiece for full disc views. I love being able to see the surface features instantly when I'm operating it at F40+. This is currently on a Twilight Nano mount which handles it great.

 

I installed a Televue sol-finder on it. Or you can use a Heliopod (Dynapod) to quickly put it on the sun. Here my ST80 is masked to 40mm F10 with the Quark and a 25mm eyepiece:

 

25397810627_e4d4920316_c.jpg

 

My 4 year old can use it even.

 

39557553344_1206da721c_c.jpg

 

Here's the same scope with a 60mm aperture mask (F6.667) that I use for imaging. You can take a look at my images to see the results. Edge to edge, the glass of the ST80 is solid. No APO needed.

 

42023864775_a7bc35dbf4_c.jpg

 

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Now, this assumes you want to continue using your Quark for grab & go visual. Maybe you want to get a dedicated, unpowered scope? If so, I would definitely look into a Lunt 60mm or Coronado 60mm. 60mm is plenty of aperture to really see some things with good detail. Quick to use with no fuss. Nothing heavy. Easy on light weight mounts. You can also purchase the front mounted versions where the etalon & ERF are a single unit installed on the front of a donor scope and a blocking filter in the back and you're set, which gives you more modular options.

 

I think this is a superior way to go personally. No power required. One single unit. The only reason I didn't is budget. I already have a Quark and I do 99% imaging with it. For a visual instrument, I'd want a dedicated scope instead. But, they are also costly. And I also use all my scopes for several purposes. So, for now, I'm using the Quark on several instruments.

 

Very best,


Edited by MalVeauX, 10 August 2018 - 11:04 AM.

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#7 44ye

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Posted 10 August 2018 - 10:34 AM

A alt / az  mount like a VIXEN PORTA II MOUNT 20 pound cap and Orion st80 would be light & potable . No counterweights no heavy GEM  No  polar alignment needed just plunk it down and align on the sun . Might handle the 12 kg of your scope and quark.Read the reviews on the lighter manual Alt / AS mounts

I was typing when Marty posted  . that is what I describing One pic is a 1000 words 

Don



#8 Jan.H

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Posted 11 August 2018 - 09:00 AM

Hi 

 

Thank you MalVeauX for a very thorough and constructive feedback. I have decide to go for a doublet achromatic refractor, probably somewhere in the range of 60 to max 80 mm.. Thank you for the links, and the very nice pictures =)...Regarding the telescope mount, it will be something similar that you have show in your pictures. Thank you to all who have contributed to this thread, your time and answers is very much appreciated.

.

Clear skies to all 


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#9 gjanke

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Posted 14 August 2018 - 05:38 AM

Out and viewing in 3 minutes or less. Always blown away. No batteries required. It also doubles as my grab and go night scope. Using this scope I have done more observing in the pass year than I have done for the past 10 years. While its not a C11 or 6" refractor it also requires minimal cool down or up and if the clouds roll in there is no crying over the time spent setting up or breaking down. I just pick it up and walk it back in the house. Clouds clear out I walk it back out.

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#10 Binojunky

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Posted 15 August 2018 - 10:04 AM

IMHO an Esprit is overkill, wasted money, get a PST or like myself a 102 mm F6.5 refractor and a good quality white light filter,D.



#11 Doug D.

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Posted 15 August 2018 - 11:08 AM

Topic just makes me wax nostalgic for the Solarscope SV50 scope I bought used many years ago after getting infected with H-alpha fever thanks to a PST.  Even used the SV50 was a fairly crazy amount of money but it was a revelation vs. the PST when I finally got to look through it.  I since moved on to a set-up very similar to gjanke's but I often think about how much I enjoyed (and miss) the SV50 - the perfect combination of portability and performance IMHO, punching seemingly way above its aperture class - a real firecracker as Ken at Solarscope would have said.

 

Anyway, not so much a recommendation as a trip down memory lane.  Maybe someday another SV50 will wander my way....

 

And not much use to OP I guess.  If you don't want a dedicated H-alpha scope, I agree with others that a triplet is not necessary for H-alpha whether adding a filter or using a Quark (although for visual, I really like views that also give me full solar disk). But if you have a triplet lying around, it ain't going to hurt either. I might also consider a longer focal length tube for solar/lunar observation.  


Edited by Doug D., 15 August 2018 - 11:10 AM.

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#12 Jan.H

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Posted 15 August 2018 - 04:21 PM

Hi

 

Next week I will be on a 3 week's vacation, so I will have plenty of time to nerds around regarding buying a small doublet achromatic refractor and a small mobile mount...... @Doug D I would truly love to have the opportunity to look through a "SOLARSCOPE SV50 ", It's 100 percent precision work  undoubtedly, but the price alone is killing me. I would have to sell my wife and hers huge amount of shoes....mhhh wait a minute maybe there's a possibility here =))

 

Take care

Jan H.



#13 Doug D.

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Posted 15 August 2018 - 05:20 PM

I hear you Jan, wasn't a serious recommendation for you but your post just made me remember what a great 'grab and go" H-alpha set-up the SV50 represents.  Used at half-price would at least make it tempting but very rarely do they come up.  Also, the law of diminishing returns definitely applies.  While the SV50 will cost many times more than a comparable aperture instrument from Lunt or Coronado, it would be hard to argue it is "many times" better.


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