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recommend me a small refractor to put a quark on


iwols
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well been round the block and back to the start again,no lunts available,doubts about the solar scout and the odd quark which cant go on my quad scope, so looking again at the quark but with a new scope,can anyone suggest a small scope that will take the quark or what do you use,thanks again

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2 hours ago, iwols said:

I was going to try the quark on my skywatcher startravel 80,any thoughts guys

Should work fine. I am a bit more downmarket with a Solar Scout but I typically use it atF22, which is roughly where you would be with the Quark 4.2 teleconverter. With an ST80 you should still be able to get a full disc. If you want to get to F30, just use an aperture mask, which should also reduce spherical aberration. 

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Ideally it should be an F/7 scope or slower if you want to achieve best surface detail without stopping down the aperture. In general, below F/30 you have light from the photosphere partly obscuring chromosphere detail. Proms will be nice and bright even at faster focal ratios, but filaments will be fainter. Of course each etalon is different, so you never know quite what you’re going to get until you test it.

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9 hours ago, Anne S said:

We use our Quark with an Altairastro Ascent f7 80mm scope.

what camera and any examples please

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7 hours ago, iwols said:

what camera and any examples please

I use an Altairastro Hypercam 174 which is a fan cooled cmos camera. It has 5.86 micron pixels and is suited to longer focal lengths. ZWO also do a similar camera. Not sure whether the fan does a great deal. It's a 1/2 inch chip. It's very easy to focus accurately.

Please excuse the processing, I need to work on it. This was taken during the previous sun cycle when there wasn't much to see.

 

93D1F18D-3030-4F82-BB48-834EDBD293D1.png

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I wouldn’t use the ST80 as a long term solution, they are quite variable in quality and can suffer from spherical abberation which can kill the detail somewhat.

A lot depends on what scale you want to image at. To get full disk views with a Quark you need a focal length of around 450mm max. This is related to the 21mm field stop of the Quark itself. If you want higher res/smaller field of view images then an 80mm or even 100mm f7 ED apo would be fine. I used mine visually in a variety of scopes; Tak FS60C, TV85, Astrotech 106mm f6.5 EDT. Great results at increasing scale and resolution. Lovely full disk views in the little Tak, but any decent ED doublet would do the trick. I do find that a good dual speed focuser really helps.

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43 minutes ago, Stu said:

I wouldn’t use the ST80 as a long term solution, they are quite variable in quality and can suffer from spherical abberation which can kill the detail somewhat.

 

Have to say I agree. It might produce satisfactory views but it won’t get the best out of your Quark. The unique thing about these ‘eyepiece’ Ha filters is you can use them with almost any refractor - the slower and bigger the better, as long as magnification and aperture isn’t too high for your seeing.

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22 hours ago, Stu said:

I wouldn’t use the ST80 as a long term solution, they are quite variable in quality and can suffer from spherical abberation which can kill the detail somewhat.

ah i was wondering about this, as i've seen the Orion ST80 as a cheap option for full disc but not seen any examples of people using it for imaging. 

 

currently to get my full disc fix after going quark, i've been putting the quark in to the Lunt35 without the rear blocking filter, so its 400mm f/11.45. i then put a 1.25" 0.5x reducer on the camera.

 

was thinking to replace this setup with an Orion ST80, which is also 400mm but if I stop it down to 35mm I could get the same focal ratio, it would allow me to sell the solar scope to someone else who would love to get in to the hobby (they're very hard to come by in New Zealand). i don't understand the optics side of it enough to know what impact spherical abberation would have to me, would it be an issue to worry bout when stopped down and using a fairly small sized sensor camera as we generally use in solar?

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9 hours ago, AmritNZ said:

i don't understand the optics side of it enough to know what impact spherical abberation would have to me, would it be an issue to worry bout when stopped down and using a fairly small sized sensor camera as we generally use in solar?

I’m far from an expert but basically it means that the optics don’t bring light from all parts of the objective to focus at the same time. It tends to kill off finer detail, with lesser impact for low power views.

Top example shows a perfect lens, bottom one suffering from bad SA.

8F8444C1-8590-4F17-9B18-18F3B523A62F.thumb.png.745db5cedf35f40f5c7502139e0eb9e8.png

I guess the most sensible option would be to try the Lunt 35 next to the ST80/Quark if you can. If the ST80 is half decent then the additional resolution should still be of benefit but likely not showing the maximum potential of the Quark. I used to have a PST (40mm) and the Quark even in a 60mm scope (albeit a Tak FS60C) knocked the spots off it even though it was a good PST.

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What about a Skywatcher 72ED? 420mm focal length, dual speed focuser, and of course, ED. Much better (but more expensive) than those nasty 80mm thingies :wink2:

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34 minutes ago, Mr Spock said:

What about a Skywatcher 72ED? 420mm focal length, dual speed focuser, and of course, ED. Much better (but more expensive) than those nasty 80mm thingies :wink2:

Nice little scopes for not too much cash 👍

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On 01/06/2022 at 19:56, Mr Spock said:

What about a Skywatcher 72ED? 420mm focal length, dual speed focuser, and of course, ED. Much better (but more expensive) than those nasty 80mm thingies :wink2:

Still too fast really at F/5.8. Should aim for F/7, or as close to it as possible, or even better above, to get best from the Quark. Also a well figured achromat is fine for hydrogen alpha. 
 

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Posted (edited)
On 02/06/2022 at 06:56, Mr Spock said:

What about a Skywatcher 72ED? 420mm focal length, dual speed focuser, and of course, ED. Much better (but more expensive) than those nasty 80mm thingies :wink2:

really don't think you need ED for solar.. if it's a multi purpose scope also for night then by all means go for it though.  my main scope is a cheap nasty doublet with no ED glass or flattener and does just fine with solar hence was querying the theory and whether anyone has matched the bad experience in theory to real experience in practice with solar in Ha. 

this is with cheap nasty doublet 127L/1200 (F9.45). 

image.thumb.jpeg.e7579b0147d13696a58333615d04a596.jpeg

 

 

I will test out the orion st80 and post up some results / review in a month or two with practical experience. 

Edited by AmritNZ
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Posted (edited)

You certainly don't need an ed scope, achromatic scope is fine. Solar imaging is only using one wavelength so it doesn't matter. I use cheap achromatic for CaK and continuum, breeser 100mm stopped down to 80mm. My Lunt 60ds is also an achro. Different if you're imaging deepsky or planet's, etc. 

20220307-130422UTellabryant-CaK-Prom-1.jpg

PSX_20220508_094454.jpg

Edited by Nigella Bryant
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43 minutes ago, Nigella Bryant said:

You certainly don't need an ed scope, aromatic scope is fine. Solar imaging is only using one wavelength so it doesn't matter. I use cheap aromatic for CaK and continuum, breeser 100mm stopped down to 80mm. My Lunt 60ds is also an acro. Different if you're imaging deepsky or planet's, etc. 

20220307-130422UTellabryant-CaK-Prom-1.jpg

PSX_20220508_094454.jpg

beautiful full disc, love the filaproms. the Orion ST80 is quite a poor performer optically so that should be a good test once I receive it about how much that side of things matters with a quark. looking forward to testing it and hope it does work out as i've just sold my lunt 35

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On 07/06/2022 at 07:22, AmritNZ said:

really don't think you need ED for solar.. if it's a multi purpose scope also for night then by all means go for it though.  my main scope is a cheap nasty doublet with no ED glass or flattener and does just fine with solar hence was querying the theory and whether anyone has matched the bad experience in theory to real experience in practice with solar in Ha. 

this is with cheap nasty doublet 127L/1200 (F9.45). 

image.thumb.jpeg.e7579b0147d13696a58333615d04a596.jpeg

 

 

I will test out the orion st80 and post up some results / review in a month or two with practical experience. 

Yes, an achromatic scope is fine for Ha solar or white light with a continuum filter, but it needs to be well corrected in Spherical Abberation to give best results. At f9.45 your 127L is slow enough to be fine I’m sure, but I wouldn’t bet on all ST80s being the same. It may look ok, but you will be missing out on the finer detail I’m sure.

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4 hours ago, Stu said:

Yes, an achromatic scope is fine for Ha solar or white light with a continuum filter, but it needs to be well corrected in Spherical Abberation to give best results. At f9.45 your 127L is slow enough to be fine I’m sure, but I wouldn’t bet on all ST80s being the same. It may look ok, but you will be missing out on the finer detail I’m sure.

Spherical aberration can be overcome by having a bigger achromat and stopping it down by 20mm Stu. They're cheap enough to go slightly bigger and stop down rather than full blown doublet ED's. And as you say, f8+ too. 

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30 minutes ago, Nigella Bryant said:

Spherical aberration can be overcome by having a bigger achromat and stopping it down by 20mm Stu. They're cheap enough to go slightly bigger and stop down rather than full blown doublet ED's. And as you say, f8+ too. 

I’m sure it can be reduced by stopping down, but I wouldn’t say bad SA can be eliminated in this way. I don’t think you have to spend a fortune, but I do think it’s worth getting a well corrected scope to get the best out of solar observing, particularly in white light where I think the detail is finer. My Celestron Omni XLT 120mm f8.3 is very good just as an example, and was not expensive at all. The 102mm f11 scopes are also well worth considering. Always seems a shame to mount, say, a big heavy 150mm scope and then stop it down.

Anyway, whatever works for people is all that matters, mine is only an opinion.

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