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Small refractor to go with Daystar Quark-C

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#1 ProfLemoi

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Posted 09 October 2021 - 02:26 PM

Having found a Celestron XLT 120 for close up views of the sun with my new Quark-C I am wondering if there might be a recommendation for a smaller refractor to get the entire disk that will work well with the Quark-C?

 

 

Thanks!
 



#2 V-Rock

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Posted 09 October 2021 - 02:45 PM

Orion ST80mm will give you a full disc of the Sun with 32mm 50° and 25mm 50° eyepieces

#3 gustavo_sanchez

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Posted 09 October 2021 - 02:48 PM

(Assuming you are talking about imaging)

Been down that same road for quite some time… for maximum contrast, a Quark asks for a f7-ish scope so you can get to the ideal f30, accounting for the bundled telecentric. But to get a full disk, you should stay below ~380mm focal length to be able to get a full disk. So that puts you in the realm of the 60mm f6 ED scopes (many brands offer this scope size). Still I’m not completely convinced that’s the way I want to go either… I’ve got a Lunt 60 MT in order just for that reason… will that scope replace my Quark for all my solar needs? I have no idea.


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#4 hopskipson

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Posted 09 October 2021 - 03:47 PM

 will that scope replace my Quark for all my solar needs? I have no idea.


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Not if you want a higher resolution that you'll get with a larger aperture.

 

I haven't used it in a while but the ST80 with an aperture mask and a 0.5x reducer was able to give me a full disk on a IMX174 chip


Edited by hopskipson, 09 October 2021 - 03:49 PM.

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#5 gustavo_sanchez

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Posted 09 October 2021 - 04:00 PM

Not if you want a higher resolution that you'll get with a larger aperture.

That's exactly the reason of my current paralysis by analysis. I'll continue on this thread since this, in my opinion, pertains to the OP's question of "which scope to use with a Quark".

For a person with fair to poor seeing during the day (99% of us), which scope size and length would strike the best balance between aperture (for resolution) and focal ratio (for contrast)? I'm guessing something like the AT102ED (102 f7), or maybe something similar to my SV90 f7 (which I don't want to detach from its fixed DSO setup).

Maybe a 80mm f7?

#6 Spikey131

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Posted 09 October 2021 - 08:05 PM

With the TV76 (480mm f/6.3), I can almost see a full disc with a Quark and 32mm Plossl.

 

But the full disc is very easily seen, with room to spare, with a TV60 (360mm f/6).  I think this is the FL to consider for full disc observing or imaging.



#7 hopskipson

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Posted 09 October 2021 - 08:59 PM

That's exactly the reason of my current paralysis by analysis. I'll continue on this thread since this, in my opinion, pertains to the OP's question of "which scope to use with a Quark".

For a person with fair to poor seeing during the day (99% of us), which scope size and length would strike the best balance between aperture (for resolution) and focal ratio (for contrast)? I'm guessing something like the AT102ED (102 f7), or maybe something similar to my SV90 f7 (which I don't want to detach from its fixed DSO setup).

Maybe a 80mm f7?

I have some of the worst seeing during the day.  I was regularly using a 102 F/7 and it was hit and miss with what I captured.  I got a Solar Sintalator Monitor and now I can measure when seeing is good or bad.  I now use a CR-6 usually masked to 120 mm.  I just wait until the seeing gets lower than 1 arcsecond and then start the capture.  I have really seen an improvement with the data I capture.

 

If I'm going for a full disk I'll use my Lunt 60 DS, but before I got this I used the ST80 masked to 60 mm to get the Quark to F/28 and then the 0.5x reducer to get the full disk.


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#8 MalVeauX

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Posted 10 October 2021 - 02:13 PM

Hi,

 

For a full disc FOV with the Quark with its internal 4.2x telecentric; a 400mm focal length base scope will do that, with around a 25mm basic plossl.

 

I would target the short 60mm to 70mm scope options that are around F6 to F7. The issue however is making sure you get a quality focuser; most of the wee archromatics in this range have poor focusers for this job. So the ED ones have better focusers, despite ED not giving you anything of an advantage with this at all. But it's the only way to get a quality focuser with the scope. Like the AT60ED for example. Great little scope for this.

 

There are some 80mm F5 flavor scopes that can be masked to be 60mm or even 40mm (F10) for example, that are excellent for this. Various flavors of the ST80 with a metal focuser will do it on the cheap (I still would upgrade the focuser).

 

If I were doing it over for this purpose; I would just get one of those AT60ED little refractors, they are inexpensive but have a great focuser and are excellent as tiny G&G fracs at night (FPL53) and terrestrial use as a spotting scope. Astronomics sells them as do others with various clone names.

 

Here's an Orion clone ST80 masked to 40mm (F10) and a Quark for a full disc FOV; I upgraded the focuser with a basic GSO/Antares single speed which is a tremendous thing to add for the mass of the Quark (and binos!).

 

60mm_HA_Binoview_Visual_01282019.jpg

 

32689712996_f1a20ac427_c.jpg

 

25397810627_e4d4920316_c.jpg

 

39557553344_1206da721c_c.jpg

 

Very best,


Edited by MalVeauX, 10 October 2021 - 02:16 PM.

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#9 betacygni

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Posted 10 October 2021 - 06:37 PM

I’m only visual, but I’d also highly suggest the astrotech AT60ED. So far I’ve used my quark with the aforementioned AT60ED, old Japanese vixen made 80mm f5, vixen made in Japan 80mm f11.4, Stellarvue 102mm f8.3, and skywatcher 120mm f5. On almost every occasion the little 60mm AT60ED provides the best visual image, followed closely by the 80mm f5 (this would be a good choice too, but modern Chinese ones have terrible focusers) then Stellarvue 102 if the seeing is really good (often isn’t, and no full disk here of course).

As mentioned above the focuser on the AT60ED is superb, carries my quark and binoviewers easily, and full disk views with 32mm or 40mm plossls. I’ve found for visual f5 to f6 shows better detail than the conventional wisdom of longer focal ratios. I suspect largely because they bump up the magnification too high for seeing to support. The slight improvement in bandpass is largely wasted in my experience.

Edited by betacygni, 10 October 2021 - 07:14 PM.


#10 ProfLemoi

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Posted 11 October 2021 - 02:19 PM

Great input.  I have an ED80T CF and have ordered a .5 reducer, figured I would give that a try WHEN I get my Quark.  I ordered it over a week ago from Daystar and it has not yet shipped.  Still showing "In Production" when they said "In Stock" I assumed they were in stock and ready to ship... :(



#11 Tom M

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Posted 11 October 2021 - 06:04 PM

Great input.  I have an ED80T CF and have ordered a .5 reducer, figured I would give that a try WHEN I get my Quark.  I ordered it over a week ago from Daystar and it has not yet shipped.  Still showing "In Production" when they said "In Stock" I assumed they were in stock and ready to ship... frown.gif

The "In Stock" for Daystar is meaningless. I had the same issue as you and finally called and found out it was going to at least a month wait.



#12 ProfLemoi

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Posted 12 October 2021 - 08:46 AM

The "In Stock" for Daystar is meaningless. I had the same issue as you and finally called and found out it was going to at least a month wait.

Oh wow... that is VERY disappointing...



#13 Second Time Around

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Posted 12 October 2021 - 11:52 AM

I chose an Altair 72mm f/6 ED.  The focal length of 432mm means that with a 25mm Plossl I can see the whole disc + prominences.

 

With the Quark's inbuilt 4.3x focal extender this gives a final focal ratio of f/26.   This is fine for seeing prominences, but for surface detail the recommended final focal ratio for the Quark is f/30 or preferably even longer.   This means a starting focal ratio of f/7+.  A common way of achieving this is by stopping down the aperture of the scope.  Unfortunately, like many others, my Altair refractor doesn't have a dew cap with a reducer.

 

I came up with the idea of using a rubber lens hood fitted over the end of the tube.  The rubber is flexible and stretches over the tube to give a tight fit.  In my case I needed an inside diameter of 88mm or a little less, to fit a filter size of 58 or 62mm.

 

A search on eBay turned up this one for £4.99 delivered: from photo-accessories-wales. This has an inside diameter of 85mm to fit 58mm filters.  The clear aperture is 54mm, so with a focal length of 432mm this gives a focal ratio of f/8 natively and f/34.4 with the Quark.

 

 

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  • 72mm stopped down.jpg

Edited by Second Time Around, 13 October 2021 - 02:25 AM.

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