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realistically, how much detail can you observe visually in H-alpha with 60mm of aperture?


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I am in the process of getting my first solar scope started - based on an ED80 refractor (stopped down to 60mm) and a Quark Combo for chromosphere, plus the required paraphernalia (3x telecentric, ERF, etc). I've done astronomy for several years before, I generally know what to expect from the night sky. But I don't have much experience with the Sun, except during eclipses and planetary transits I've done some casual observations and a few images - all in white light.

So... how much detail can you see, realistically, in an H-alpha scope at D=60mm? I know from white light there's a lot of low scale detail (granules? I don't have the proper terminology here) that's only visible in post-processing from an image stack (similar to planetary imaging). Also, in white light, visually you can clearly see sunspots, but that's about it - but how much extra detail can you see in H-alpha besides the sunspots? I know imaging with a CMOS can extract a lot of detail in post, but I have no concept of what you can see on your own in the eyepiece.

I know we are at low solar activity right now.

I've figured out it's best to keep magnification pretty low.

My long term goal is to do imaging in H-alpha (and perhaps calcium too), but I also enjoy visual astronomy.

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I'd say the sun is well worth observing at 60mm. I observe h-alpha in 60mm, 85mm, 100mm and 120mm scopes. There is plenty of detail in all of those but I like using the 100mm the most for visual,

In a 60mm scope I'd expect the view to look a bit like this lovely image by Alexandra Hart, taken with a 40mm PST I believe: Except with less contrast and a monotone red colour. You might po

I would have rejected that one!, all of the 40mm PST's that I have owned gave far better images than that.  I think the GONG solar images are a better representation of what can be seen with a good 40

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Sounds like a good project! Can I ask why you are stopping down to 60mm when you could enjoy the views at 80mm with better resolution?

I’ve used a Quark (not combo) in a variety of scopes from 60 to 150mm, and the one I had was very good. Even at 60mm (Tak FS-60C) it was a significant step up from my PST40 and showed full disk views with excellent detail. I generally used it in my TV85 and saw lovely prominences, filaments, the spicule line and many surface features. The only concern is about Quark variability; some are good, some less so, so hopefully you get a good one.

I do think increased aperture can really help, although with a Quark that can mean  higher powers so the conditions have to support that. For white light solar I use up to x200 with a Herschel wedge in a 100mm apo, and also have a 102mm PST mod which gives excellent high power views. In white light this allows granulation, faculae and fine detail in the active regions to be seen visually.

I hope you enjoy your scope.

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10 minutes ago, Stu said:

Can I ask why you are stopping down to 60mm when you could enjoy the views at 80mm with better resolution?

They say the Quark operates best at f/30 and above. My scope is f/7.5 and I use a 3x telecentric. So I need to stop it down a bit to reach f/30.

After I get everything working properly I will experiment with aperture, etc.

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24 minutes ago, Florin Andrei said:

They say the Quark operates best at f/30 and above. My scope is f/7.5 and I use a 3x telecentric. So I need to stop it down a bit to reach f/30.

After I get everything working properly I will experiment with aperture, etc.

Yep, makes sense, but I think a x4 at full aperture would be well worth trying. Higher powers of course but if conditions are right then the results would be good.

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I'd say the sun is well worth observing at 60mm. I observe h-alpha in 60mm, 85mm, 100mm and 120mm scopes.

There is plenty of detail in all of those but I like using the 100mm the most for visual, which for me is the sweet spot of detail to aperture in my typical conditions. For grab and go, I prefer the 60mm.

Really, any aperture is worth it, I have had some cracking views through 40mm PSTs.

I would say, they all give much more detail than planets in a large scope, plus the sun is very dynamic.

Edited by Luke
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I started with a 50mm scope. Even with 40mm/50mm, you can see most of the Sun’s chromosphere features very clearly. As you go up in aperture, you can resolve finer detail though. So I agree with Stu - definitely try it with your 80mm scope.

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21 hours ago, Stu said:

Yep, makes sense, but I think a x4 at full aperture would be well worth trying. Higher powers of course but if conditions are right then the results would be good.

Right. I'll do that eventually, that's the plan, but for now I want to see the whole solar disk at once. I'm pretty sure the disk will get clipped by the Quark at 4x extension (F=2400mm, so the solar disk would be 21mm in prime focus).

I will also run it at 4x for highest detail imaging with a good camera, to zoom into smaller features. But that's for later.

16 hours ago, Highburymark said:

I started with a 50mm scope. Even with 40mm/50mm, you can see most of the Sun’s chromosphere features very clearly. As you go up in aperture, you can resolve finer detail though.

Like small scale granulation? Or just sunspots and plages?

I've seen lots of images taken in H-alpha, but I have a hard time reconciling what I see there with what I could see with my own eyes in a small solar scope. I know there can be a large difference in detail between planetary imaging and planetary visual observations - I don't know if the same applies to H-alpha solar.

Basically, the info I'm trying to get here is to allow me to diagnose potential issues with the system. If I turn it on and all I see is a big red pill with a few dark spots, despite all the tuning, something's definitely wrong. But I don't know what's a reasonable amount of detail that would indicate the system is operating well enough. I only looked in an H-alpha scope once, briefly, many years ago, and I don't remember much.

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In a 60mm scope I'd expect the view to look a bit like this lovely image by Alexandra Hart, taken with a 40mm PST I believe:

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Except with less contrast and a monotone red colour. You might possibly see finer detail at higher magnification in good conditions and the proms might be easier to see than in this image.

The spots and their surrounding areas should be fairly easy to see and the strandy dark filaments should be relatively dark and stick out.

Images usually show much higher contrast than what you would see at the eyepiece.

At 60mm you should be able to glimpse similar detail all over the disc as in the PST shot, but it may be difficult to properly see it depending on the filter, a bit like how it can be challenging to discern detail on planets. The struggle is due to low contrast I find.

I find seeing spicules possible but tricky at 60mm. Fairly easy at 85mm. And gorgeous and immediate at 100mm.

How contrasty the view is and how well proms stick out varies from filter to filter and you may find there are sweet spots in the view where to better see a feature you need to nudge it to the right place in the view.

Re: how well the filter is performing, I would suggest to post an image if possible and to ask the imagers. They may be able to spot any issues or advise if the tuning is right.

Edited by Luke
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If the limb or edge of the disk is nicely sharp then the disk itself should have some sort of "granular" look to it.
Like a Christmas tree, glass bauble which has been given a coarse "sugar coating" to represent frost or snow.
This graininess may not cover the entire disk. You do need some practice to fully enjoy H-alpha views.

When I first started visual H-a the surface graininess would drift in and out of focus.
As if my eyes were really struggling to focus. I had over 50 years of practice with every other kind of subject.
Then after a while of concentration and relaxation I would be finally be able to force my eye to "lock onto" the surface.
It would then appear like a finely textured bed of coals with glowing cracks between the grains.
This is a rather "flowery" description and the true scale of the overall features was tiny.
I am simply trying to suggest my own perception of the appearance at the time. Once focused the surface would remain continuously visible.

Quarks have a very poor, online reputation for quality control. Forum members, here and elsewhere, have returned numerous examples for exchange.
This is the main reason I have not invested in one myself. I persevere with my endless PST mods. Nor do I need to use such extreme focal ratios.

A very good Quark may beat a PST mod. A good PST may match or beat a Quark. I have seen absolutely stunning "live" videos from both.
If you have an astro camera, then a few seconds of "live" video [posted on YT or elsewhere] will tell us far more than a fuzzy single [chance or lucky] image.
You don't usually have the ability to "mess" with video [with free software] like you can so very easily with stills.

Here's a video with a similar level of surface detail you should be seeing routinely: The size of the disk will vary with the instrument and eyepiece.

 

 

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I would have rejected that one!, all of the 40mm PST's that I have owned gave far better images than that.  I think the GONG solar images are a better representation of what can be seen with a good 40mm on a good day.      🙂 

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4 hours ago, Peter Drew said:

I would have rejected that one!, all of the 40mm PST's that I have owned gave far better images than that.  I think the GONG solar images are a better representation of what can be seen with a good 40mm on a good day.      🙂 

Hi Peter,

My PST ITF was DOA. So I never enjoyed Gong quality images with it. :crybaby2:

I'd reject GONG H-a too if that was all I was seeing.  :p


PS. You had a mention on Astrobiscuit [on YouTube] when he bought Big Bertha. A 10" F/6 Astrosystems 'scope.
He's taking some nice images through it from his rather wobbly, flat roof in London. :thumbsup:

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  • 3 weeks later...

Ok, I'm probably doing something wrong. All I see is a smooth red ping-pong ball. No details. If there are any sunspots (right now there aren't any, but I've seen some in the past few weeks), I see them quite well. The edge is sharp enough. Basically, everything I see in the 50mm viewfinder which is equipped with a Baader solar film, I also see in the big scope, except it looks red.

I've done visual observations and even imaging before, in white light, during eclipses and the transit of Venus. I was able to capture enough detail and even some granulation in the camera. I'm new to H-alpha but not new to astronomy in general. Here's the total eclipse captured with this ED80 a few years ago:

This is the H-alpha system I've built this winter:

 

halpha-stack.thumb.jpg.55923d7f7279158cf4c784c622f0ac42.jpg


- Orion ED80 with a 60mm iris in front (not seen in the image) to keep f-ratio at f/30
- Moonlite 2.5" focuser - fresh install, replacing the original Orion focuser (it was time to upgrade anyway)
- Baader UV/IR cut filter (allows 656.28nm)
- Baader 3x telecentric (threaded into the focuser using a custom T adapter - no smooth bore couplings, it's all threaded)
- DayStar Quark Combo Chromosphere threaded into the telecentric (a 1.25" camera nosepiece installed backward serves as a T adapter)
- cheap diagonal
- GSO 0.5x focal reducer
- bunch of 1.25" extension tubes calculated to have the focal reducer actually operate at exactly 0.5x
- TeleVue Plossl 40mm

 

The Quark receives a cone of light at f/30 (D=60mm, F=1800mm). The reducer cuts that down to F=900mm. The magnification at the eyepiece is 22.5x.

I moved the tuning knob on the Quark through the whole range, tested every step. I always wait for the LED to turn green before I observe, which always takes a few minutes after each adjustment. Not a hint of detail anywhere that cannot be attributed to white light.

I've replaced the diagonal and the eyepiece with a 0.8x reducer and an APS-C camera, and I don't get any H-alpha detail there either - but I didn't try the whole range on the Quark tuning knob, only the center. I've captured 1000 frames and stacked them. These are the first 10 frames:

https://florinandrei-astrophoto.s3-us-west-1.amazonaws.com/halpha-no-detail.zip

The Quark is new, I bought it a couple months ago from an online astronomy shop.

Any suggestions? What should I try next?

Since I have no experience with hydrogen alpha, I don't know what to expect. Is the Sun so quiet these days that no details are visible for visual observations in a small aperture?

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All Quarks seem to need experimenting with the adjustment depending on the default tuning position and they all vary.  I think it is too early to suspect that it is faulty.  Despite the general lack of solar activity there should always be a pronounced surface texture to the solar disc.      🙂 

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4 hours ago, Florin Andrei said:

It makes literally no difference no matter how I turn the tuning knob. Even if I power off the Quark, the image is the same.

Looks like a very well put together system. One question though, what happens if you take the reducer out of the equation? Probably no change, and I’m assuming it is after the Quark (ie eyepiece side)?

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On 18/01/2021 at 05:12, Florin Andrei said:

Ok, I'm probably doing something wrong. All I see is a smooth red ping-pong ball. No details. If there are any sunspots (right now there aren't any, but I've seen some in the past few weeks), I see them quite well. The edge is sharp enough. Basically, everything I see in the 50mm viewfinder which is equipped with a Baader solar film, I also see in the big scope, except it looks red.

I've done visual observations and even imaging before, in white light, during eclipses and the transit of Venus. I was able to capture enough detail and even some granulation in the camera. I'm new to H-alpha but not new to astronomy in general. Here's the total eclipse captured with this ED80 a few years ago:

This is the H-alpha system I've built this winter:

 

halpha-stack.thumb.jpg.55923d7f7279158cf4c784c622f0ac42.jpg


- Orion ED80 with a 60mm iris in front (not seen in the image) to keep f-ratio at f/30
- Moonlite 2.5" focuser - fresh install, replacing the original Orion focuser (it was time to upgrade anyway)
- Baader UV/IR cut filter (allows 656.28nm)
- Baader 3x telecentric (threaded into the focuser using a custom T adapter - no smooth bore couplings, it's all threaded)
- DayStar Quark Combo Chromosphere threaded into the telecentric (a 1.25" camera nosepiece installed backward serves as a T adapter)
- cheap diagonal
- GSO 0.5x focal reducer
- bunch of 1.25" extension tubes calculated to have the focal reducer actually operate at exactly 0.5x
- TeleVue Plossl 40mm

 

The Quark receives a cone of light at f/30 (D=60mm, F=1800mm). The reducer cuts that down to F=900mm. The magnification at the eyepiece is 22.5x.

I moved the tuning knob on the Quark through the whole range, tested every step. I always wait for the LED to turn green before I observe, which always takes a few minutes after each adjustment. Not a hint of detail anywhere that cannot be attributed to white light.

I've replaced the diagonal and the eyepiece with a 0.8x reducer and an APS-C camera, and I don't get any H-alpha detail there either - but I didn't try the whole range on the Quark tuning knob, only the center. I've captured 1000 frames and stacked them. These are the first 10 frames:

https://florinandrei-astrophoto.s3-us-west-1.amazonaws.com/halpha-no-detail.zip

The Quark is new, I bought it a couple months ago from an online astronomy shop.

Any suggestions? What should I try next?

Since I have no experience with hydrogen alpha, I don't know what to expect. Is the Sun so quiet these days that no details are visible for visual observations in a small aperture?

On mine I can see prominences without it being turned on. Solar disk detail becomes available with a low setting and solar self heating takes it past the tuned point so an erf is becoming essential . This is used with a SV80 Refractor so it's within the aperture range. Turn your heater settings right down and work through the range. 

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1 hour ago, skybadger said:

Also, why are you using a x3 Barlow when the quark has its own x4 built in ?

The Quark Combo doesn’t have the 4x telecentric so you need to introduce your own to get up to F30ish.

I had a regular Quark that showed prominences with no power and changing the powered setting made no real positive difference. I added a 35nm HA filter as an ERF but it didn’t help. I returned it and the replacement only worked under power as I was expecting, and there was a definite setting where I could see surface detail better. Unfortunately there was also a very pronounced vertical sweet spot. 

I did spend time checking the different settings over multiple sessions and at different times of the day. Even though surface detail was sometimes hard to come by I could almost always see prominences.  

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14 hours ago, Stu said:

Looks like a very well put together system. One question though, what happens if you take the reducer out of the equation? Probably no change, and I’m assuming it is after the Quark (ie eyepiece side)?

If you look at the image of the system, the eyepiece appears to be very tall. That's because there are several 1.25" extension tubes plugged into it, with the 0.5x reducer threaded like a filter at the end of the tubes. This is calculated to deliver exactly 0.5x magnification, based on the distance/magnification table for this reducer (distance from reducer to field stop). So yeah, it's after the Quark, of course. :)

Without the reducer, the image is larger and more dim, as expected. Still no changes - it looks like a regular white light image, just painted red. No prominences, no granulation, nothing. I did see a sunspot a few weeks ago (but now there are no sunspots). Again, identical to what I would see in a white light filter (Baader solar film) in terms of details, just the color is different.

Power on, power off, turning the knob through the whole range (waiting each time for the green light before observing) - make no difference.

There's noticeable haze over the whole image, also visible in the camera. It would not hide details, except those that are very low contrast (I don't see H-alpha details anyway, so this is hypothetical), but it's clearly there. In the past I've done white light imaging, and there was less haze and the background was much darker with the Baader solar film.

Also, with the ASI camera installed instead of the diagonal + eyepiece, literally all joints in the system are threaded - there's no smooth bore / compression ring joint anywhere. I expected that to be rock solid. Well, no. There's a bit of lateral slack in the system, and it's internal to the Quark. It's between the main body (red cylinder) and the forward-facing black ring (which then continues with the 1.25" snout). It's enough to cause dozens of pixels of image shift, or more, on a 5k resolution APS-C sensor. Is that normal with the Quark?

I did not try to fix it, due to the very clear warnings on the DayStar site against tampering with the etalon, so I just took notice of the issue.

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The symptoms suggest , that for whatever reason, your Quark isn't coming "on band".  I'm sure you've gone about testing it correctly which leaves the Quark a faulty suspect.  Time to contact Daystar I think.       🙂

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28 minutes ago, Peter Drew said:

The symptoms suggest , that for whatever reason, your Quark isn't coming "on band".  I'm sure you've gone about testing it correctly which leaves the Quark a faulty suspect.  Time to contact Daystar I think.       🙂

I will do that. Thanks everyone for your help!

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Personally I'd be looking for a second hand Lunt 60mm and eventually add a double stack at a later date. I'm biased though, lol. I can visually see plage, filaments, prominence, spots, spicules, flares, the orange 🍊 peel affect, etc. 

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42 minutes ago, Nigella Bryant said:

Personally I'd be looking for a second hand Lunt 60mm and eventually add a double stack at a later date. I'm biased though, lol. I can visually see plage, filaments, prominence, spots, spicules, flares, the orange 🍊 peel affect, etc. 

I thought about that. But the long-term goal, and perhaps a bit unrealistic, is to be on the lookout for a very large (full-aperture) ERF and eventually move the H-alpha stuff to a bigger telescope. May or may not pan out that way. We'll see. First, I need to make it work with the small aperture. :)

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I also ended up with a used Lunt LS60 after returning my Quarks. It is a different experience i.e. full disk and better suited in my opinion for quick looks/setup. However it does not take magnification very well - could just be my sample though. Although the Quarks I had didn't deliver much on surface detail the higher-magnification views of spicules and proms through my 76mm and 100mm refractors were very good and I do miss that. If I had bought the Lunt new I think I would have been disappointed after owning the Quarks, but maybe that's not fair considering the greater aperture scopes that the Quarks were used with. Using the Lunt with the DS unit really does make a difference surface detail wise and overall I am happy with the scope visually, despite what I consider to be the need to use it at a low magnification (30x). As I start to dabble in imaging I am sure the desire for larger aperture and higher resolution will creep back in but maybe this time I will either think about the Lunt Calcium K module for use with the 100mm refractor, or a Solar Spectrum filter as an alternative to a Quark. A way off having to make that decision though, however I understand your long-term goal as it's what attracted me to the Quark in the first place.

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My secondhand PST etalon works fine with larger apertures. [150mm f/8 & now f/10]  :biggrin:

I'm usually watching a section of a high res, H-a disk nearly three feet in diameter on my 27" monitor. :p

All the fine surface detail and proms at the same tuning point. Instant tuning too. :thumbsup:

Half the price of a Quark on their QC lottery. :wink2:

Whoops! Did I just go off-context? :icon_clown:

Silly me! B)

 

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