Quark newbie question.

[Franklin]

Just got hold of a Daystar Quark "Chromosphere" eyepiece and am looking for information on tuning principles. On first set up I had the tuning dial set in the middle, as per the instructions, and was very pleased (actually astounded) with the view once it warmed up and got on band. Viewing before the yellow light turned green I could see the usual WL detail in a red light and got focus on a sunspot group, then as the Quark warmed up the solar limb began to show fibrous detail which slowly crept in towards the center of the disk. After a while I realized that I was seeing the Sun in Ha for the first time and the more I looked, the more I could see. The whole disk had turned into a seething mass of Ha detail and the solar limb was encircled by a curtain of spicules with some huge prominences flaring off into space. Absolutely amazing and I can't wait for the Sun to come back out for a proper session. So do I just leave it set in the middle as the default setting? Not sure what the +/- 0.1A click-stops represent and what effect changing this will have on the initial views. Does tuning to a lower setting improve on surface detail and tuning to a longer wavelength improve on prominence detail? I know I will probably just have to experiment to fathom it out but I did try tuning on either side of the middle setting and it didn't seem to make much difference, though I only had a brief moment between the clouds. Any advice from experienced Quark users would be appreciated.

[Stu]

Sounds like you’ve got a good unit there Tim. I had some tremendous views with my Quark in various scopes and it sounds like you are getting similar views. I love viewing the spicule line, so much to see and ever changing.

As for tuning, I never really found much benefit in changing it from wherever I found the optimal position to be. I believe this changes with each unit as the etalon varies in tolerance.

I found this article which may be of interest:

https://www.star-gazing.co.uk/WebPage/guides/tuning-a-quark-for-solar-viewing/

[Franklin]

2 hours ago, Stu said:

I never really found much benefit in changing it from wherever I found the optimal position to be.

I'm beginning to think the same. After a morning thunder storm, the clouds cleared for an hour and I'm chomping at the bit to get out with this thing. Set up with the little FL55SS, 32mm prism diagonal and UV/IR cut filter on the AP for tracking and the Quark's center setting was the best again. At only 300mm FL I've got a perfect full disk view with an SLV20mm and also I can see the eyepiece field stop nice and clean, whereas the NPL30 plossl showed vignetting from the etalon's smaller clear aperture. Tried the 8-24mm zoom which was good at the 24mm setting but became quite soft when zooming in, maybe it's the seeing and there was some hazy high cloud cover so will wait for better conditions before giving my verdict. Waiting on a 2" UV/IR cut so I can get the 2" diagonal set up with the SD115 and Quark for some higher power views with the bino's. Exciting times!

 

[Nik271]

Congratulations! Quarks are great aren't they. I've tried mine on 70mm F6 and 100mm F7 refractors and it works in both very well. The .1 angstrom adjustments are to make it possible to center the bandpass of the etalon exactly on the Ha emission line, it will not make it wider or narrower. In practice I have not seen much change from a single or double click away from the central position, however when I move it right to the end I begin to see loss of contrast. 

What will change the width of the bandpass is the focal ratio of the scope. I note yours is F5.5 which while still nominally ok is not ideal, something like F7 or F8 will show a more contrasty view of the disc features. I tried this with my 70mm F6, stopped it down to 50mm and the view of the filaments, while dimmer seemed a lot more contrasty. For prominences wider is actually better, so you can leave it at F5.5.

Not much sun today here, but hopefully more to come next week! 

Edited June 18, 2023 by Nik271

[Franklin]

5 hours ago, Nik271 said:

I note yours is F5.5 which while still nominally ok is not ideal, something like F7 or F8 will show a more contrasty view of the disc features. I tried this with my 70mm F6, stopped it down to 50mm and the view of the filaments, while dimmer seemed a lot more contrasty. For prominences wider is actually better, so you can leave it at F5.5.

Thanks @Nik271, I'm very impressed with the Quark and I've only had a couple of quickies really. I tried the F/5.5 to see if I could get a full solar disk and I can which is great and also the prominences did seem more pronounced with it but I just thought that may be the seeing. I have an 81mm and 115mm, both at F/7.7 which should be ideal and also an 80mm achro at F/11.4 which according to Daystar is not ideal but I've read reports that the Quark works well at these F/40 ratios, obviously the image scale will be massive so I suppose it all depends on the seeing or maybe these reports are referring to imaging. Either way I will enjoy finding out I'm sure and my next plan, weather permitting, is to mount the SD81 with the Quark and the A80M with the Lunt wedge side by side so I can do some WL observing whilst waiting for the Quark to warm up. Although it is early days for me and my Ha baby steps, the unit I have seems to work best at the moment, for my eyes, when the tuning knob is set at center, though I'm aware that different conditions may change this and as soon as we get some proper day-long clear skies I will have the time to experiment with the different settings to find out exactly where the true on band position is. I've enjoyed observing the Sun in WL over many years, by projection, solar film and nowadays a solar wedge but I have to say that after seeing the daily sunspot groups and any faculae my sessions would be quite brief but now with this Quark I can't stop looking, it's just amazing!

[JeremyS]

I find with my Quark, setting the knob to the left (cooler) a little helps bring out contrast (Tak FC 76DCU)

Edited June 18, 2023 by JeremyS

[Franklin]

16 minutes ago, JeremyS said:

I find with my Quark, setting the knob to the left (cooler) a little helps bring out contrast (Tak FC 76DCU)

Maybe your Quark needs to be a little cooler because you're using it in such a hot little telescope😁.

[Franklin]

Managed a few more sessions with the new Quark in between the clouds and have tried it on a number of different scopes now. The DayStar advice is that around F/30 is ideal so the SD81S at F/33 should be perfect and it is. I can't get a full disk but I nearly can using an NPL40mm. The A80M is getting closer to F/50 and as you'd expect the image scale is much greater, nice to have but it needs very good seeing. This combo is probably better suited for imaging close ups which is something I don't do at present. Going back to the little FL55SS and at only 300mm focal length it operates at about F/23 with the Quark and in this configuration I can get full disk with the NPL40, NPL30, NPL25 and SLV25. The SLV12mm gives nice close up views but dims the image which is to be expected with only 55mm of aperture. I much prefer viewing the Sun at this kind of image scale because the whole image is much sharper, the detail pops out at me and it handles moderate seeing conditions. The central setting on the tuning knob is where I start a session and I've now found that a click or two to the left gives a more detailed view although the difference is very slight. I was leaving the power on after the green light came on and have now tried turning it off and did notice a slight increase in contrast as it cooled, so from that I assume I was a little off band when powered up, it has been very warm in the Sun though recently. It seems the advice to get the Chromosphere version is correct as Ha surface detail and prominences are nicely visible together.

So in conclusion I am very pleased with the Quark but have to agree with earlier comments that it's almost like you need to change scopes rather than eyepieces to get  different views.

 

 

[Roy Challen]

Agree with previous comments, changing the tuning subtly affects the contrast rather than making big differences to the view.

An 18mm Baader BCO just about gives a full disc view but I use the 32mm plossl 90% of the time.

I leave my Solarscout in the 3 o'clock position.

Edited June 25, 2023 by Roy Challen

[Paz]

I find the tuning knob at -4 or -5 works best for me. At first I didn't notice much difference and for quite a time the amount of detail presented in Ha was more than I could take in anyway.  But the more I have observed in Ha the more apparent the difference between the settings becomes.

[Marke998]

I decided to test my Quark out at different setting and the results were dramatically different at different positions., Much to my surprise, turning the tuner as far as I could counterclockwise gave me the best results. All images wre processed and sharpened in AS3 but no other edits have been done. I've annotated the positon in each image from full on (fully clockwise) to full off (counterclockwise).

[Franklin]

This is all new to me but the way I gauge the setting, after only a few trials, is to just observe even whilst the things warming up and when there appears to be more Ha detail than regular sunspot detail I know I'm about right. Different sessions have needed slightly different settings, presumably due to differences in the ambient temperature at those times. 12 o'clock seems good and going counter-clockwise to 9 o'clock as well depending on the conditions. When observing early in the day the middle setting worked best but when using the Quark in the heat of the midday Sun I find I need to tune it to the left a little to get the best view. Plenty of Ha surface detail and prominences showing well.

[JeremyS]

Generally a few notches CCW works best for me too