Need a full disc HA sidekick (PST/Quark/??)

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MalVeauX
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Need a full disc HA sidekick (PST/Quark/??)

Post by MalVeauX » Sat May 27, 2017 8:57 pm

Hey all,

I currently do high(ish) resolution HA & white light imaging with my 120mm refractor and a Quark and various white light filters. It suits me for now for my level of seeing commonly. I have done full disc in the past with a wee 50mm guidescope that I stop down to 27mm aperture and also use a focal reducer on the Quark to get a full disc FOV with my camera's sensor size (ASI174MM). But, that resolution is really poor, and it just looks messy.

I'm considering trying to build or modify something to make it easier to go full disc with some things I have, or to be modular so that I can go from higher resolution to full disc with similar equipment.

I'm considering a few entry options that maybe I can get advice on:

1. Quark Chromosphere. I have this already. If I could remove the internal 4.2x telecentric barlow, maybe I could use that with a shorter scope, stopped down, to effectively image full disc? My Quark's barlow doesn't just unscrew. I think there is a bolt on the side that locks it up. And I'm not sure if its sealed with locktite or something. I've yet to really wrench it apart as its my only HA filter and I'd rather not damage it with my inexperience. But I'd love to hear more about how this could be possible to use for full disc without using tiny apertures and focal reducers to get there. I have a 50mm (190mm 3.8) guidescope and an Orion ST80 (400mm F5) refractor that can be turned into anything.

2. PST. I have seen tons of resulting mods with this, from SCT's to inserting it into another refractor. I'm very interested in it because it seems it can be made to go from full disc to a really high resolution setup with an SCT and an D-ERF (I'd love to one day use a 9.25" with full aperture D-ERF and a PST etalon mod maybe). I don't have a PST though, but I could get one. I'm just curious if it would be possible to use it stock for full disc with an ASI174MM, or if I'd have to modify something. I don't want to have to use a barlow just to get focus, I'd rather find a way without that if possible. I've seen images of PST's shoved into the back of other refractors. That's interesting. Or just harvesting the etalon out of the PST and making it work with another refractor. I'm curious what kind of thing could be made with an Orion ST80, if any?

3. Forget all this and just use my ST80, stopped down, Quark, Focal Reducer and a bigger sensor camera to change FOV?

Note: Mosaics have been problematic for me because of uneven fields with my Quark. For a full disc, I'd love to just do it in one shot.

Looking for ideas to compliment what I have, or use what I have already.

Very best,

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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by MalVeauX » Sat May 27, 2017 10:46 pm

On another note:

I've tested my ST80 (400mm) with the Quark and both a 1.25" and a 2" 0.5x focal reducer (200mm) with my ASI174MM and an APS-C dSLR and the vignetting is really bad, it takes up so much of the FOV that it renders using the focal reducer useless basically. I can get a full disc with the dSLR. But with the ASI174MM it just hugs the edges and would require a mosaic, but with bad vignetting its hard to even do a good mosaic without issues. I can't for the life of me figure out why the 2" focal reducer has such bad vignetting. It's on the camera side of the Quark where it should be, as close to the camera sensor as I can get it. Ideas?

Very best,

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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by MalVeauX » Mon May 29, 2017 9:36 pm

Hrm,

Still tinkering with some ideas.

PST - This is high on my list right now simply because its versatile. I can use it right away with a short low profile nose and my ASI174MM for full disc right away without modification. Plus it's portable and can go everywhere, no setup time, no power, etc. Simple. I like that. Light weight. Can piggy back my high res system even. If and when I decide to modify things, I can sacrifice it to become a different system with PST stage mods. That's very interesting in general. And for a $450 used, approximately, cost, that's a cheap way to get into the game.

Quark - I don't think I'll be able to reliably and satisfactorily do full disc with a quark unless I can take out that 4.2x barlow. I could trade my Quark out with a Combo unit maybe, and have that opportunity, but I'd still need to use a 2x barlow, which is still hard to do full disc with and maintain F30 at a minimum. The Quark is really just not meant for full disc imaging, it's more of a high res targeted system. I would love to be able to make mine work without the barlow, but I don't want to damage my Quark as it seems to be better than an average Quark based on the filtration I'm getting at the continuum (at least others have told me so, so far) represents a tight bandpass compared to normal. But who knows? I still would rather not damage it. Awaiting to hear that it's a simple, safe procedure to take out the barlow. Amazing that I can't find a single example of it on the web with confirmation other than 1 thread here on SolarChat with pictures, but zero followup or examples of it working (ugh).

External Etalon (40mm, 50mm) - There's also the idea of using a 40mm or 50mm external etalon like a SolarMax or Lunt, usually for double stack, or just for the front of a refractor. They cost more, but are modular in that I can move from scope to scope. This is very interesting to me. I've also seen mods of these used in larger scopes. But ultimately this is very costly and I spend more time in high res, so not sure I want to go this far.

As it is, I can do full disc with the following:

Orion ST80 (with center cap removed, stopped down to 42mm aperture, 400mm F9.5 effectively) -> Extension 2" tube (only because I don't use diagonals) -> Quark -> 0.5x Focal Reducer -> APS-C dSLR (ugh). It works. But it's not very good, grainy, messy looking at best.

My other method:

50mm Guidescope (190mm F3.8) with helical focuser (with a 27mm aperture lens cap on there to stop it down to F7) -> Quark -> 0.5x Focal Reducer -> ASI174MM. It works. But, 27mm aperture means very little detail, other than huge surface structures, so its not ideal.

I could do mosaics, but so far, it's problematic for me because of uneven fields with my Quark. I guess I could try again now that I have more experience with processing mosaics.

Very best,

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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by soulvagabond » Tue May 30, 2017 8:11 am

My Quarks barlow was easy to remove, without damaging anything. You can screw on the Powermate 2x, instead and upgrade the blocking filter to 25mm from Andover . The native bf filter is Andover's 12.5mm.
As for the F/30 focal ratio, it's probably overrated, Daystar claims similar performance from 15 to 30.
Personally, I don't see much of the difference in between my F/5 and F/7.5 scopes. The contrast is about the same.

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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by MalVeauX » Tue May 30, 2017 11:28 am

soulvagabond wrote:
Tue May 30, 2017 8:11 am
My Quarks barlow was easy to remove, without damaging anything. You can screw on the Powermate 2x, instead and upgrade the blocking filter to 25mm from Andover . The native bf filter is Andover's 12.5mm.
As for the F/30 focal ratio, it's probably overrated, Daystar claims similar performance from 15 to 30.
Personally, I don't see much of the difference in between my F/5 and F/7.5 scopes. The contrast is about the same.
Heya,

Interesting. Was the barlow sealed with some kind of glue? Or was there a bolt/screw you had to undo first? After taking out the barlow, did you have to insert a blocking filter some how, and if so, where? Appreciate any info.

Very best,

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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by marktownley » Sun Jun 04, 2017 10:24 am

I think something like a PST or lunt 50/60 (both ideally doublestacked) is the best full disk option.
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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by FeroT » Tue Jun 06, 2017 2:48 am


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Re: Need a full disc HA sidekick (PST/Quark/??)

Post by MalVeauX » Tue Jun 06, 2017 1:46 pm

Update:

Well I decided I didn't want to take apart my Quark just yet and potentially damage things.

I found a deal on a used PST and picked it up for an acceptable price for its condition. I'll test it out soon. Picked up a low profile nose piece for my 174MM too to compliment it.

Naturally, the storms are now worse, as I have picked up two solar toys now in a month and so I will never see the sun again I'm sure. :(

Very best,

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