Daystar 80mm Quark bundle scope questions

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Robert Henry 1355
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Daystar 80mm Quark bundle scope questions

Post by Robert Henry 1355 » Mon Jun 27, 2016 12:09 am

Hello-
Does anyone have the Daystar 80mm Quark bundle scope? If so,and you have the prominence version,any pros/cons? How do the filaments look against the solar surface? I see no solar finder.Can you use a Sol-Searcher on this scope? How strong is the focuser with the weight of the Quark on it?Any "slop" that is noticeable? I have the chromosphere version that I use on Orion 80mm,100mm,and 120mm scopes,but my Orion 80mm ST scope really is not meant for the Quark and would like to use the Daystar 80mm refractor for full disc views of prominences and filaments.Would it be worthwhile to spend $1450 on this scope?I have Minitower II mount and would like to put 80mm Daystar on 1 side with 1 Quark,and 120mm on primary side with other Quark and have dual scope setup. All replies much appreciated.
Thanks,
Bob

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Re: Daystar 80mm Quark bundle scope questions

Post by Derek Klepp » Mon Jun 27, 2016 4:43 am

Bob I think you could find a cheaper one.I have the Old Daystar Solaredi scope but it is retrofitted with the Quark.Its adequate but not overly used.I just find it almost impossible to get the whole disc on band with the Quark and don,t think it was designed for that purpose.I may be wrong though.I would keep experimenting with what you have.I would save my money for now and perhaps try to view some whole discs through other scope just for reference.
Just my thoughts regards Derek

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Re: Daystar 80mm Quark bundle scope questions

Post by marktownley » Mon Jun 27, 2016 5:21 am

If you have the Quark already I would just get a good 80mm scope to use it on. I use a skywatcher ed80 with the quark and it is brilliant though not full disk. There are loads of good 70mm f6 or 80mm f5 scopes out there that you could use to get a full disk that will be cheaper than the daystar bundle.
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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Tue Jun 28, 2016 8:20 pm

The Daystar 80mm Quark bundle is just an ordinary 80mm scope supplied with a Quark. If I am not very much mistaken it is made by Long Perng. Compared to your Orion 80mm ST, the Daystar branded scope does have a better focuser. As it is also an F6 as opposed to F5 scope it will also have views with the Chromosphere Quark that are more contrasty because the Quark will work a little better. However don't expect too much. I use to demonstrate an 80mm F6 APO Triplet with a Quark and views, compared to using an F8 (or even an F7) scope, were much warmer and lower contrast.

One thing I don't agree with on Daystars advert is it says 'maximum aperture and focal length that can pass a full disk'. Without modification the longest focal length eyepiece you can use with a Quark is a 40mm Plossl which I think is also the best. Using our 80/480, the full disc filled the whole eyepiece with nothing to spare.

One thing for sure that will be a pain with this scope is the mounting. Having tested an 80mm triplet with the same type of L shaped bracket, the weight of the scope is all at the back because the lens is very light. A Quark is quite heavy so this makes things worse. You need to fix a long dovetail to it to have a chance of finding balance.

I would stick with what you have. Nothing that will give a real full disc (if thats what you want) will also be F7+ which will give you the best contrast.

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Re: Daystar 80mm Quark bundle scope questions

Post by Robert Henry 1355 » Tue Jun 28, 2016 11:05 pm

Thanks Derek,Mark,and Astrograph for your help.Having a Quark Chromosphere model for high resolution views of the solar surface,I was looking into getting a Lunt 50mm DS to view whole disc and for filaments on surface.I looked thru one this year with a Lunt zoom and was amazed at what this little scope can do! Just need ~$2000 laying around the house first.
Bob

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Re: Daystar 80mm Quark bundle scope questions

Post by marktownley » Wed Jun 29, 2016 7:28 pm

Hey, here's an idea Robert, just replace the focuser on that ST80 for something a bit more meaty and you're onto a winner. Easy to fit a solar finder too, and much cheaper than the Daystar.
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Re: Daystar 80mm Quark bundle scope questions

Post by Robert Henry 1355 » Wed Jun 29, 2016 10:44 pm

I had the same idea,Mark,about 2 weeks ago,and didn't know if the 80mm ST would be worth putting a $200-$400 ( GSO and Moonlite) focuser on it.Your reply makes me think a little bit more about using this scope for solar. Not sure the optics on the ST would be worth it,even though an achromat would be fine for solar,but this scope new is only about $150, so lens may not be the best?
Thanks again,
Robert

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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Thu Jun 30, 2016 8:45 am

To be blunt guys, the optics in all these budget scopes will be about the same. The main issue with Chinese optics is consistency of build. Alignment and spacing of lens elements tends to vary. If your unhappy with the basic results of the ST then don't assume that spending only a little bit more will improve anything. The main limitation of your ST with regard to solar is its F ratio. With a Quark this will only result in an F21.5 beam running through the etalon so it won't be working at anything like its best. Once you get to F28+ you see a transformation in contrast. To get there with your ST you would need to stop the front aperture down to 57mm as that will increase the F ratio. You will have less resolution but more contrast.

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Re: Daystar 80mm Quark bundle scope questions

Post by Robert Henry 1355 » Thu Jun 30, 2016 7:29 pm

I didn't realize the importance of the f/ratio in contrast with the Quark.I have a 120mm f/8.3 achromat in storage.According to Astrograph,this scope would get better contrast than my f/5 or f/6.Has anyone compared their Quark with different f/ratios? By the way,thank you Astrograph,for your knowledge on the f/ratios with Quark.

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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Fri Jul 01, 2016 10:23 am

The F ratio dictates how parallel light rays are. You can appreciate how a short low focal ratio scope (which is physically short) bends light very sharply and that a long focal ratio scope (that is a physically long) bends light much less. All filters work best when light hits them perpendicular to the face.

If you put a light pollution filter on a wide angle camera lens you will see that there is a ring around the edge of the image where the filter has been less effective. This is because the light around the edge of the image is passing through the lens at an angle so the filter does not work as well. The narrower the band pass of a filter, the more critical that the light passing through it is parallel and arrives at the face of the filter perpendicular to it. Daystar quote F30 as being the target F Ratio where the light passing through the etalon meets this criteria. If the light is not parallel then the filters band pass will vary across its surface. In extreme cases you will see a hot spot where the image is lacking in contrast completely and just bright. This is why you must use a tele-centric lens with a rear mounted etalon. Any multiplier lens will increase the native focal ratio by the amount of its multiplier but a tele-centric does this and outputs a parallel beam. A barlow outputs a diverging beam. If correctly designed the image formed by a tele-centric does not increase in size over distance but a barlows does.

It should be noted that a tele-centric like any other lens will be optimal with a specific focal ratio and length. This is because it can only turn a certain angle of incoming light rays into a parallel beam. The tele-centric fitted to the Quark must therefore have a sweet spot. I have no idea what this is but the best views always seem to be with F7-F8 scopes.

See below a graph taken from Daystars White Paper showing the effect of F ratio on band pass. You can see that at about F28 the filter begins to operate at its best. Therefore this is a target I normally suggest although F30 and more is going to be the ideal.

Your 120mm F8.3 Achromat would offer far, far better views than your 80 for two reasons. Apart from running at F35 and so getting the best contrast out of the Quark that is possible, it also has 50% more aperture and therefore will be much higher resolution. As it is also a native F8.3 it should also have less spherical aberration and therefore focus sharper. The downside to the scope is that you have 4282mm of focal length compared to 1720mm so you will only be observing a small section of the sun although that view will be far more impressive.

To improve the field of view you can add a tele-compressor. This is a reducer but designed to work with a parallel beam of light as opposed to a converging beam. This is why adding one of those cheap 0.5x reducers to the back of a Quark never works. They are designed for converging beams.

Until recently the only 'solar' Tele-compressor I knew of was Baaders 0.7x. This is very good but also has 2" SC threads and is a pain to fit. Daystar are releasing a 0.5x / 0.33x tele-compressor for the Quark but when, I don't know. In theory this would let you get a full disc again with the bigger scope.

If you do decide to use your 120/8.3 then I recommend a new energy rejection filter. Daystar suggest that you can use a UV/IR cut up to 150mm (actually they say 120mm in the Quark manual and 150mm in the Combo manual). I disagree with this. The amount of energy still getting through a UV/IR on a 100mm scope is noticeable although this is killed by the Quarks own blocker. Personally we recommend the use of Baaders 2" 35nm H-Alpha filter as an ERF above 100mm. It works much better.

Hope this all help
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FWHM vs Fratio.jpg
FWHM vs Fratio.jpg (59.58 KiB) Viewed 1883 times

Robert Henry 1355
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Re: Daystar 80mm Quark bundle scope questions

Post by Robert Henry 1355 » Fri Jul 01, 2016 11:21 am

Thank you,Astrograph,for the awesome help and knowledge you have on this subject.
Much appreciated!
Bob

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Re: Daystar 80mm Quark bundle scope questions

Post by nicosolcy » Thu Jul 07, 2016 10:16 am

Long time lurker, first post here. Regarding telecompressors there is another option in the market by Optec: http://www.optecinc.com/astronomy/catal ... extgen.htm

Again, these are threaded for SCTs so appropriate adapters would be required but still - another option.
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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Thu Jul 28, 2016 8:01 am

Dear nicosolcy, the Optec models are not tele-compressors, they are reducers. They are, like other reducers, designed for a converging beam. The output from a rear mounted filter system that uses a tele-centric is parallel so a normal reducer causes distortion so you cannot use them unless it is with a very small chip camera.

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Re: Daystar 80mm Quark bundle scope questions

Post by nicosolcy » Thu Jul 28, 2016 8:44 am

Thanks Astrograph! Good to know what is of use and what is not suitable!
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Re: Daystar 80mm Quark bundle scope questions

Post by estrela1969 » Sun Dec 17, 2017 7:46 pm

@ Astrograph: "Personally we recommend the use of Baaders 2" 35nm H-Alpha filter as an ERF above 100mm. It works much better." Sorry for asking again. Just wanted to make sure I got it right: If I would like to use the Quark on my 120mm refractor, I srew put the Baader 2'' 35nm H-Alpha into my diagonal instead of using an ERF top mount or a UV/IR filter? With better results in visual observing as well (I don't do AP). Thank you in advance for confirmation, I'm new in solar observing and don't have much experience with filters in general.

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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Tue Dec 19, 2017 9:07 pm

Hi, welcome to Solarchat!

For a 120mm Refractor the 35nm Ha filter will look after your Quark better than a UV/IR cut. Understand though that a good front mounted filter (like Baaders D-ERF) will give you sharper / better contrast compared to an internal filter.

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Re: Daystar 80mm Quark bundle scope questions

Post by christian viladrich » Mon Dec 25, 2017 4:47 pm

Hi,

If it is of any help, here is the impact of the F/D ratio on the effective FWHM of an Ha filter :

Image

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Re: Daystar 80mm Quark bundle scope questions

Post by Astrograph » Thu Dec 28, 2017 2:19 pm

I'd tend to agree with Christian on this, but visually once the F ratio gets to F28+ you begin to see what the filter is capable of. Quarks are hit and miss anyway but using an otherwise genuine chromosphere filter on say an 80mm F6 (F25.8) results in a featureless red ball. The same filter on an F7 (F30.1) and definitely an F8 (34.4) provides the sort of chromosphere contrast and detail you might expect.

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