Florin Andrei

Problem solved. Looks like the unit had some issue, maybe it was damaged in shipping, who knows. Anyway, DayStar fixed it under warranty. Now I see granulation all over the disk, a small spot on one side surrounded by bright areas, a long thin dark line in the middle of the disc, and various prominences around the edge, of all shapes. It's at low activity, so there aren't that many big features, but the filter definitely works. The background is very dark. Thanks everyone for your help!

@Rusted - you nailed it. Aries ERF + 200mm SCT is the long-term goal. It should also be able to work in the calcium band. Also - replace the ERF with Baader solar film and you have a great machine for white light imaging. There will be hurdles on the way to that goal, I'm sure, mostly related to the ERF availability and price. We'll see. I'm not afraid of DIY and designing/building systems from scratch. I've a degree in Physics, I've built a dobsonian from scratch (including the mirror), I've built a mirror grinding machine, and now I'm working on a second, larger mirror for a bigger dobsonian. Future plans include even larger, more complex systems, perhaps a corrected Dall-Kirkham hybrid, for which I made a few blueprints in OSLO. I need to figure out what is the practical limit, in terms of diameter, for custom ERFs. A compact, lightweight cDK could do double duty as hydrogen/calcium imager during the day, and DSO imager during the night. But that's for much later, if it will happen at all. Okay, enough daydreaming, I'm back to the salt mines.

I always appreciate how much I learn from these impromptu discussions. This is great, it's like I'm back in school again. @Rusted and @astro_al could you please point me at some good material regarding the usage of small Coronado-like etalons with larger apertures? What are the limitations? I will do my best to try and build an H-alpha stack around my 200mm SCT, if I can - in the long run. Well, at least I will see how close I can get to that. There are many, many hurdles to clear on that path (the price and scarcity of full aperture ERFs for example). One unknown is seeing - but I live in a place where seeing at night tends to be pretty good (no jet stream, near an ocean, etc). I guess daytime seeing should follow similar patterns (maybe overall not as good due to the extra thermal energy).

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.

I will do that. Thanks everyone for your help!

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.

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.

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: - 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?

Finally I decided to upgrade the focuser on my ED80 refractor to the Moonlite 2.5". It was time to do that anyway. Very impressed with literally everything about that focuser: execution, feature set, visual design. They have threaded adapters for every format out there, including T2. So I was able to thread the 3x telecentric directly into the focuser. No smooth bore joints anywhere - it's all threaded all the way to the camera. So, with everything installed, I grabbed the butt end of the camera and wiggled it left-right-up-down. To my great surprise, there was a bit of play in the stack - and it was in the Quark etalon itself! Oh, no... It's internal to the Quark, it's between the main body (red color) and the black ring facing the scope. It's not any of the threaded connections. It's not a lot of wiggle, maybe 1 or 2mm at the butt end of the camera. Still, it seemed a bit underwhelming, after all these efforts to make the system rigid. Keep in mind, I have not tested the system yet - I'm very busy with work, and the Sun is pretty quiet these days. So it may still work. But my question is - how typical is this? Does this sound familiar? Which side is the actual etalon mounted on internally? Is it the scope side ring? Or the other side?

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. 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.

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.

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.

So I did some googling and all I can find are 180mm Baader DERF filters. Do they make bigger sizes?

Thanks for all the information, this is very helpful. I've found a CN thread where the stop is said to be 21mm, located at the exit: https://www.cloudynights.com/topic/619797-help-calculating-fov-for-visual-eyepieces-with-quark-chromosphere/ More interestingly, there's another CN thread where Jen (the owner of DayStar) says "a 90mm F/6 = 540mm using a 4X powermate, then a Combo Quark will pass a full disk". https://www.cloudynights.com/topic/534692-daystar-quark-combo-the-new-sctrefractor-model-impressions/ That's D=90mm, F=2160mm, f/24. I only need it to work at D=60mm, F=1800mm, f/30, which should be easier.

I see. If I plug the eyepiece directly in the Quark Combo, that would definitely work, because it's very close to the filter. If it's further away (there's a diagonal, etc), then it depends. With the camera, I'll have to keep the sensor as close as possible to the filter. Shorten that side of the stack. Do you know where the 21mm aperture is? Is it at the exit from the Quark? Where do I start measuring?

No, for the full disk I plan to use an APS-C sensor, which is 23.6 x 15.6mm, with 4.78 micron pixels. I am aware this is far from ideal sampling, and I don't care. I have other plans for ideal sampling imaging. My concern is how to get the full, unobstructed image of the solar disk in the focal plane with the Quark Combo. This is for both visual observations and imaging, and the quality of imaging will not be ideal, I know. Knowing the diameter of the blocking filter, to determine the size of the largest unobstructed image in the focal plane, seems like I would have to assume a certain distance between the focal plane and the blocking filter, is that right?

I'm thinking to get a DayStar Quark Combo filter for hydrogen alpha (chromosphere version). The instrument I will use is the Orion ED80, at D=80mm, F=600mm, f/7.5 focal ratio. A 4x telecentric barlow will put it at F=2400mm, f/30 focal ratio, which is how the Quark Combo likes it. After the Quark I will use a focal reducer to keep the f-ratio in line with the pixel size on the camera (I have not decided yet which camera I will use, but it will likely be something along the lines of ASI290MM, 2.9 micron pixels, implying a reducer around 0.5x). That's all good. Occasionally, I would like to observe, and perhaps also image, the whole disk of the Sun at once. To observe it, I will just have to use an eyepiece with the appropriate focal length and FoV. To image it in prime focus, I have an APS-C sensor, which is 15.6mm on the small axis. I realize imaging quality in this case will not be best, but that's okay, and I hate doing mosaics. The question is, how to do it. If you look at the Quark Combo product page... http://www.daystarfilters.com/COMBOQuark.shtml ...they say: "Full disk viewing possible on refractors up to ~1800mm focal length". If that's the case, for full disk I could use a 3x telecentric, which would give me F=1800mm at the etalon. To keep the focal ratio at f/30 (so the etalon maintains good contrast), I could stop the aperture down to 60mm. The Sun would be 16.8 mm in the focal plane. To make the Sun fit on the APS-C, I would only need a mild focal reducer of around 0.8x, which I already have. Or I could just plug an eyepiece in after the Quark for visual observations. How does that sound? Anybody done this before? Am I missing something? Thanks!

There are several ways a motor could fail. Apparently a fairly "popular" one is for the encoder to go bad. The encoder is the device that tells the controller how much the motor has actually rotated (a feedback mechanism), so the controller knows what to tell the motor to do next. If that estimate goes bad, you can imagine how things start spinning out of control. The encoder is physically part of the motor, they're a single unit. I believe that is the cause of failure in my case. Hard to tell without opening it up - and even then I'm not sure. I've placed an order for the replacement with Celestron, but the lead time they gave me is about 1 month. I don't have a lot of options right now, so I gave them the go ahead. If anybody has a better source for spare motors, please chime in.

Is that related to the extra wires going to RA?

I've had the CGEM for several years. I even did the Hypertune procedure myself a couple years ago. Recently the RA axis started spinning fast in one direction as soon as I start alignment (or bypass it). No matter what, the RA just keeps going clockwise forever, fast. I opened the mount and swapped motor cables: plugged the RA motor into the DEC connector on the motherboard, and the DEC motor into RA. The problem stays on the RA axis. So it must be motor-related. I don't remember much from the Hypertune process (rushed it in one afternoon) and I can't find the Hypertune DVD which had detailed disassembly instructions. So I'm trying to figure out how to remove the motor when I find a replacement. Is it as simple as undoing the two big Allen bolts and pulling it out along with the motor bracket supporting it? Or is it meshed with something that would prevent me from doing so? I also seem to remember there's some fine-tuning related to the position of the motor, hence the two oval holes on the motor bracket.