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Old 24-10-2017, 04:24 PM
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Visionary (David)
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Solar Filter Advice

Every evening the clouds move in on what had been otherwise a cloudless sky. I want to beat the clouds to the punch and do some Solar observing. I a have a good APO 130mm with a good mount, what would you advise re Solar Filters?
Thanks

Last edited by Visionary; 24-10-2017 at 04:41 PM.
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Old 25-10-2017, 08:24 AM
Star Catcher (Ted Dobosz)
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Hi David

Well it really depends on what part of the spectrum you want to observe? The cheapest option is to go with white light broadband viewing. In this mode you can see details in the sunspots, faculae and granules.

The cheapest and best way to view these is to get yourself some Baader solar film rather than a glass based filter. I have found the film superior to my previous glass filters. You can buy a finished Baader film product with aluminium frame or you can easily DIY a round frame from a container lid by cutting a hole and attaching the film.

An even better result (more expensive) is to buy a Herschel wedge. Once again the best wedge is made by Baader but a Lunt wedge is a very close second and cheaper. Your aperture is at the limits of these wedges to handle the heat so you will need to add a 2 inch UV/IR block filter at the entry point of the diagonal to reduce the heat stress.

If you want to see actual filaments and prominences you will need a hydrogen alpha (Ha) filter and there are several ways to go. In my view, seeing you have a refractor, I would choose a Daystar Quark Chromosphere version. This will give you close-up views of the sun's details but not the whole disk. These are not cheap ($1500+) but will give you the biggest aperture (brightness and resolution) Ha scope for $$s spent. You will also need a UV/IR filter ahead of the Quark to reduce the heat stress. I use one with my 127mm APO.

All other options start to look at a separate Ha scope which have far smaller aperture per $$'s spent. For instance if you want a 100mm Lunt Ha scope which is 30mm smaller than your refractor you'd be spending $8000!! The Quark is attractive because it makes dual use of your scope.

The benefits of a separate solar scope however are the wider field of views that you would get of the sun. You will not be able to achieve a full disk view with the Quark on your refractor, even with a focal reducer. But you will get dramatic close up views of activity with a 25-30mm eyepiece. I have a dedicated Lunt solar scope and I prefer close-ups views on my dedicated solar scope and frequently use higher powered eyepieces.

Hope this helps with your decision.

Ted
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Old 25-10-2017, 12:00 PM
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Visionary (David)
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Quote:
Originally Posted by Star Catcher View Post
Hi David

Well it really depends on what part of the spectrum you want to observe? The cheapest option is to go with white light broadband viewing. In this mode you can see details in the sunspots, faculae and granules.

The cheapest and best way to view these is to get yourself some Baader solar film rather than a glass based filter. I have found the film superior to my previous glass filters. You can buy a finished Baader film product with aluminium frame or you can easily DIY a round frame from a container lid by cutting a hole and attaching the film.

An even better result (more expensive) is to buy a Herschel wedge. Once again the best wedge is made by Baader but a Lunt wedge is a very close second and cheaper. Your aperture is at the limits of these wedges to handle the heat so you will need to add a 2 inch UV/IR block filter at the entry point of the diagonal to reduce the heat stress.

If you want to see actual filaments and prominences you will need a hydrogen alpha (Ha) filter and there are several ways to go. In my view, seeing you have a refractor, I would choose a Daystar Quark Chromosphere version. This will give you close-up views of the sun's details but not the whole disk. These are not cheap ($1500+) but will give you the biggest aperture (brightness and resolution) Ha scope for $$s spent. You will also need a UV/IR filter ahead of the Quark to reduce the heat stress. I use one with my 127mm APO.

All other options start to look at a separate Ha scope which have far smaller aperture per $$'s spent. For instance if you want a 100mm Lunt Ha scope which is 30mm smaller than your refractor you'd be spending $8000!! The Quark is attractive because it makes dual use of your scope.

The benefits of a separate solar scope however are the wider field of views that you would get of the sun. You will not be able to achieve a full disk view with the Quark on your refractor, even with a focal reducer. But you will get dramatic close up views of activity with a 25-30mm eyepiece. I have a dedicated Lunt solar scope and I prefer close-ups views on my dedicated solar scope and frequently use higher powered eyepieces.

Hope this helps with your decision.

Ted
Ted,

That's very helpful, thank you. The Daystar/Quark is pointing me in the direction I was seeking, close-up rather than full disk. I am really reluctant to add another OTA to my gear, already my APO seems excessive for my abilities.

Many thanks

David
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Old 26-10-2017, 06:58 PM
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mental4astro (Alexander)
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I too have a Daystar Quark, with mine being the Prominence model. I use it in an ED80 scope. What this scope/filter combination can do is amazing. I chose the Prom model over the Chromosphere as proms are what most attract me. The Chromosphere detail is still there, but it is a bit more tricky to tease out.

I tried my Quark in some 8 different refractors, achromatic and apochromatic, and despite the image being monochrome, the best image comes from Apos. Sharper and more contrasty.

There are three main drawbacks to a Quark. One is the fine tuning is electronically controlled and the tunung tajes some time to happen. The other is the built-in 4.2X barlow really pushes up the magnification. That's why a 25mm / 32mm plossl is used. The ED80/Quark/25mm combo gives 101X, which with solar viewing is a helk oc a lot, and makes it very sensitive to seeing conditions. The third is the small blocking filter in the Quark means there is no advantage gained with using an 82°eyepiece - you just won't get such a wide AFOV. Long focal length eyepieces are best with this filter. This also means that with a 32mm EP and my ED80, I do not get a full disk image. You will not get anywhere near a full disk with a 130mm Apo.

I was able to get a full disk comfortably with an 80mm f/5 achro, but I prefer to forsake a full disk image for the stonking good image quality of the ED80. And with the proms being my main fare, I am not concerned I cannot get a full disk.

What I have been able to pull out detail wise with this scope/Quark combo is extraordinary. I had a 60mm Coronado double stack for a time - the Quark crapped all over it for prom detail!

For me, despite the drawbacks, I am very happy with my Quark. Makes use of an existing scope and gives me the prom details I always wanted.
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Old 27-10-2017, 09:38 AM
Star Catcher (Ted Dobosz)
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Quote:
Originally Posted by mental4astro View Post
I too have a Daystar Quark, with mine being the Prominence model. I use it in an ED80 scope. What this scope/filter combination can do is amazing. I chose the Prom model over the Chromosphere as proms are what most attract me. The Chromosphere detail is still there, but it is a bit more tricky to tease out.

I tried my Quark in some 8 different refractors, achromatic and apochromatic, and despite the image being monochrome, the best image comes from Apos. Sharper and more contrasty.

There are three main drawbacks to a Quark. One is the fine tuning is electronically controlled and the tunung tajes some time to happen. The other is the built-in 4.2X barlow really pushes up the magnification. That's why a 25mm / 32mm plossl is used. The ED80/Quark/25mm combo gives 101X, which with solar viewing is a helk oc a lot, and makes it very sensitive to seeing conditions. The third is the small blocking filter in the Quark means there is no advantage gained with using an 82°eyepiece - you just won't get such a wide AFOV. Long focal length eyepieces are best with this filter. This also means that with a 32mm EP and my ED80, I do not get a full disk image. You will not get anywhere near a full disk with a 130mm Apo.

I was able to get a full disk comfortably with an 80mm f/5 achro, but I prefer to forsake a full disk image for the stonking good image quality of the ED80. And with the proms being my main fare, I am not concerned I cannot get a full disk.

What I have been able to pull out detail wise with this scope/Quark combo is extraordinary. I had a 60mm Coronado double stack for a time - the Quark crapped all over it for prom detail!

For me, despite the drawbacks, I am very happy with my Quark. Makes use of an existing scope and gives me the prom details I always wanted.
Agree with Alex's comments. I also have the prominence version because I was more interested in prominences which can be very dynamic in close-up. The chromosphere version will still get you good prominences but not as bright. In the chromosphere version the surface features will be more prominent but it is still subtle increase unless there is significant activity like dark filaments or sunspot areas. Using solar Ha for surface details does require your eye to get accustomed to observing subtle surface details, especially at the higher magnifications.

I use my Quark with 127mm refractor more than my Lunt 80. For double stacking I tend to use the Quark combined with the DSII Unit of the Lunt 80 in my 127mm refractor. If I want DS view at full disk level I put on the double stack unit onto my single stack in the Lunt 80.

Ted
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Old 27-10-2017, 02:04 PM
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mental4astro (Alexander)
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There is another alternative, a PST conversion. This involves taking the rear section of a PST and installing onto a larger aperture refractor of f/10.

Merlin66 is very knowledgeable about these conversions. I'm contemplating doing one with the PST I have. I also have a suitable donor scope. All I need now is the ERF and adapter to fit the PST box to the donor scope. Already having this great Quark, I just lack a little more of a nudge to complete the conversion...
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Old 27-10-2017, 02:50 PM
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Alex, et al.
Yes, a good PST mod will give just as good views as a Quark, but when you add up all the costs - ERF, Donor f10 scope, Adaptors and a good PST it's almost as much as a Quark!
The only issue with a simple Stage 1 Mod is you are still limited to the 5mm blocking filter (where a 10mm would be much much better) and the imaging backfocus is still a limitation and can be a real PITA.
A stage 2 mod plus a BF10 or BF15 is the way to go, but again even more expense.
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Old 01-11-2017, 10:22 AM
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MattT
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Alex and Ken,
I found this on YouTube.....https://youtu.be/ubj-eWYyzUY

Is this the mod you mention?

I have a very nice 90mm f11 Achro with GSO focuser that I could use....no problem with cutting the tube, would this work as a donor scope?

A list of parts would be good too....it’s a bit confusing right now

Cheers

Matt
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Old 01-11-2017, 10:38 AM
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Merlin66 (Ken)
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Matt,
drop me an email and I'll send you a copy of the PST Mod write-up.
Main points:
The PST etalon must positioned 200mm inside prime focus - once positioned it NEVER moves again - so no real need for a focuser up front.
An ERF either at the front aperture or internal is mandatory.
Focusing is done behind the etalon - the eyepiece/ camera moves NOT the etalon - the back focus will be 200mm.
Ken
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