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Quark Full Disc at F6.3

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#1 HCR32

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Posted 25 August 2019 - 07:14 AM

I have a Quark chromosphere and at the moment have it running on an F8.5 scope and get just over a quarter disc at the ep. I’m trying to source a reducer to reduce scope down to F6.3 and wanted to know how much of the suns disc will I get at the ep with this up grade to determine if it’s worth doing or buying a new scope. Anyone have any experience with a Quark at about f/6?

#2 hopskipson

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Posted 25 August 2019 - 08:09 AM

Make sure you use the focal reducer after the Quark.  The Quark works better at higher focal ratios, more contrast on surface features.  I use a cheap .5x focal reducer mostly for imaging.  A nice alternative scope is the Orion ST80. I can get a full disk with a 25mm eyepiece. It's great for proms at its native focal ratio and comes with an aperature mask for more details of the surface.



#3 MalVeauX

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Posted 25 August 2019 - 08:21 AM

I have a Quark chromosphere and at the moment have it running on an F8.5 scope and get just over a quarter disc at the ep. I’m trying to source a reducer to reduce scope down to F6.3 and wanted to know how much of the suns disc will I get at the ep with this up grade to determine if it’s worth doing or buying a new scope. Anyone have any experience with a Quark at about f/6?

I would highly suggest that for similar cost to buying reducers, consider just adding a small 400mm focal length refractor to your kit and use that, full disc view without any special anything. A Meade Adventure Scope or similar (ST80 basically) will provide a full disc FOV with a Quark with a 25mm eyepiece. Anything near that 400~500mm range will work for this.

 

Very best,


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#4 HCR32

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Posted 25 August 2019 - 08:26 AM

Dame focal reducer has to be place before the quark, it’s an Astro Physics unit the screws into the 2.7” focuser. Is it really going to take away that much from the views?

#5 HCR32

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Posted 25 August 2019 - 08:27 AM

I have an option to buy a stellarvue nighthawk 80mm f7. Would that do a better job?

#6 MalVeauX

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Posted 25 August 2019 - 08:46 AM



I have an option to buy a stellarvue nighthawk 80mm f7. Would that do a better job?

That won't produce full discs either. Nice scope though!

 

400~450mm focal length with the Quark and a 25~32mm eyepiece provides full disc FOV. But really needs to be closer to the 400mm side of things.

 

I'm not sure where you can buy from in Australia, but I would again look to the 72~80mm F5~F6 scopes and source one with a strong focuser or one you can replace the focuser on. An inexpensive achromat will do fine here (ST80, etc). You can probably still get away with a 1.25" focuser, if it's strong.

 

Here's an 80mm F5 (ST80) with a 2" focuser handling a Quark and all that. Full disc FOV with room to spare. 

 

32689712996_f1a20ac427_c.jpg

 

Very best,


Edited by MalVeauX, 25 August 2019 - 08:49 AM.

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#7 George9

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Posted 28 August 2019 - 03:12 AM

Just for the record, the Quark works well at f/6.3, at least when that is the native focal ratio of the scope (130mm f/6.3). I am not sure what effect the focal reducer will produce. If f/8.5 gives you a quarter disc, then I guess f/6.3 will give you about a third of a disc. Better to get an inexpensive small scope, as noted above.

 

George



#8 HCR32

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Posted 28 August 2019 - 05:57 AM

I’ll be giving it a go at 765mm and 640mm focal lengths. I’ll see how these two scopes work out. If I can get a good chunk of the disc in the fov I’ll be happy even if it’s not the entire disc. For reference at 1020mm with a 36mm ep this is the view. Can’t get anymore tighter from here with the proposed focal lengths. 

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#9 HCR32

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Posted 31 August 2019 - 11:49 PM

How much of the disc will you get with a 640mm fl scope??


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