Send some solar scope suggestions?

[raadoo]

I'll join the myriad of SGL members asking for scope suggestions, as I'm well aware that October and its imminent partial solar eclipse are not that far into the future and I should really get some practice with solar imaging before those glorious few minutes of occlusion. Let's make a short list of things to keep in mind:

• Used primarily for imaging (H-alpha)
• Reasonable priced, <€2K
• Reliable (I've read too many horror stories of rusty filters and sloppy focusers)
• Available, i.e. not having to wait for three months for one

And a couple questions I hope you may be able to answer:

• Is Quark-ing my Askar FRA400 a better route?
• Smaller aperture new scope or larger aperture used scope?

I happily invite any left-field alternatives to the above.

[Elp]

From the off you'll need something like 400mm or less focal length to get full disk views, if youre imaging you'll need a decent sized sensor otherwise the image will be "zoomed in". With my Coronado PST I can view full disk but need a 2x Barlow lens on the front of my 290mm to get focus, which means I have to image at a squeeze two panel or three or four panel mosaic.

For solar imaging you need to image reasonably fast (micro seconds) to get surface detail, then overlay a stacked image of that over a prominences shot (where the sun is bright white).

The smallest HA scopes Lunt 40, Coronado PST, Daystar Solar Scout aren't really designed for imaging but are your lowest cost of entry and people have imaged with all of them after a bit of trialling. Even with a Daystar Quark you'll have to try a bit (and that will also be a zoomed in view).

The Coronado PST will need it's ITF filter replacing every few years if it hasn't been kept in a dry environment if it's the newer blue coloured front objective lens type (with the ITF after the prism diagonal mounted in the eyepiece holder tube), I believe Lunts also need this small filter replacing, they're not too expensive or difficult to change. All solar equipment will also be subject to variability between pieces therefore the visual result will also vary, I think this is narrowed down the more expensive you go (it can get hideously expensive very quickly).

It you want to see fine detail, larger aperture is the way to go, with refractors which are generally/only the best to use for HA, anything over 100mm aperture is recommended to use a DERF front mounted filter which also aren't cheap.

Edited July 6, 2022 by Elp

[inFINNity Deck]

1 hour ago, Elp said:

From the off you'll need something like 400mm or less focal length to get full disk views, if youre imaging you'll need a decent sized sensor otherwise the image will be "zoomed in".

Whether or not a full-disc view can be achieved depends not only on the scope, but on the scope/camera combination. I use a Lunt LS80THA, which is 560mm focal length, in combination with a 2x PowerMate and  QHY163 mono (same chip as ZWO ASI1600). This set-up gives great full-disc images in H-alpha with room to spare. Easiest way to test this is using Stellarium. Simply define the scopes, cameras and barlows you may want to use and you can test on-screen if that is a suitable combination.

But we can do the calculation ourselves: If you know your smallest imaging chip size (the height) and the focal length of the scope/barlow combination, the chip size in arc-minutes follows from 3438 x [chip size in mm] / [focal length in mm].

Examples (solar disc is approximately 31 arc-minutes):

LS80THA/QHY163/2x Barlow: focal length = 2 x 560 = 1120mm, chip height = 13.2mm => image height = 3438 x 13.2 / 1120 = 40.52 arc-minutes
SkyWatcher Esprit 150ED/ZWO ASI1600: focal length = 1050mm, chip height = 13.2mm => image height = 3438 x 13.2 / 1050 = 43.22 arc-minutes

The Esprit150 is of course not a H-Alpha scope, but is only used to show that focal length below 400mm is not required. If you would create a solar scope from it, it would give full-disc images at amazing detail.

Your Askar FRA400 has a focal length of 400mm. So if you want to do full-disc imaging, you need a chip at least 32" x 400 / 3438 = 3.7mm height, but then there is no room to play. A ZWO ASI74MM would do (sensor height 7.13mm).

1 hour ago, Elp said:

It you want to see fine detail, larger aperture is the way to go, with refractors which are generally/only the best to use for HA, anything over 100mm aperture is recommended to use a DERF front mounted filter which also aren't cheap.

From 100mm diameter upwards you will get nice details ('hair') of chromosphere.

When using a Quark a cheap achromatic telescope should be just fine as there will be no issues with chromatic aberration (you are only looking at H-alpha). I have no experience with Quarks, so cannot give any further recommendations in that respect.

Nicolàs

[Elp]

Quarks work best around F30, they have an f4.2 Barlow built into them so you multiply the scope F ratio by 4.2 to get the final stop number. Some people use an aperture mask on the front objective which in effect changes the f stop of the scope, this is done to provide better contrast.

Quarks take time to warm up (around up to 10 minutes) which uses mains power or you can use a usb power bank, a warm up time is also involved if you change the band of tuning (so you have to wait), from cold the quark acts like a white light filter. Coronado and Lunts are mechanical so you don't have the wait factor.

[raadoo]

Thanks for the detailed answers @Elp & @inFINNity Deck !

Sounds like neither the Quark, nor the entry level offerings from Lunt or Coronado/Meade are long term scopes and would likely lead me to think about “upgrading” down the line. With solar scope prices being what they are, I think it’s probably wiser to step up to a dedicated >60mm H-alpha scope from the get-go?

[inFINNity Deck]

I think that indeed it is wiser to get a dedicated scope to start with.

May I suggest (if you not already have done so) to search this forum and the SolarChat forum for examples of what you want to achieve and choose the make and model based on that? When you go for Lunt and want to do imaging then the pressure tuners are the way to go, as the tilt tuners generate ghost-images. Getting rid of Newton-rings can be done using a camera-tilter or by adding an ADC in the imaging train (I use the latter).

A highly recommended read (before buying a scope) is C. Viladrich, e.a., Solar Astronomy: Observing, imaging and studying the Sun, (Saint-Lys, 2021).

Nicolàs

 

[raadoo]

25 minutes ago, inFINNity Deck said:

I think that indeed it is wiser to get a dedicated scope to start with.

May I suggest (if you not already have done so) to search this forum and the SolarChat forum for examples of what you want to achieve and choose the make and model based on that? When you go for Lunt and want to do imaging then the pressure tuners are the way to go, as the tilt tuners generate ghost-images. Getting rid of Newton-rings can be done using a camera-tilter or by adding an ADC in the imaging train (I use the latter).

A highly recommended read (before buying a scope) is C. Viladrich, e.a., Solar Astronomy: Observing, imaging and studying the Sun, (Saint-Lys, 2021).

Nicolàs

 

Fantastic tips, Nicolàs!

[michael.h.f.wilkinson]

I hav eimaged with a humble Lunt LS35 THa, a Coronado SolarMax-II 60 mm,  and an APM 80mm  F/6 triplet with ERF, Baader TZ-4 4x tele-centric Barlow, and a Solar Spectrum 0.3 Å H-alpha filter. In the latter I could only image parts of the sun and needed to stitch the result. The differences between the set-ups can be seen below (click for full size view)

If you can get something like a secondhand LS50 or 60, or a SolarMax 60, that would be a great start.

[Carbon Brush]

I used to own a PST. As a place, point, look instrument, it was good.
Just focus then twist the etalon to see if there is anything to be seen today.
As others have reported, adding a camera to the PST was at best a faff and realistically quite a clumsy affair.

These days I get my Ha fix from a Lunt LS60. Which gives better views than my PST did.
Caveat. Performance of individual Ha scopes does vary.
The Lunt is heavier so more demanding of the mount.
I run it on a Solarquest mount, taking care with balance.
It is the pressure tuned version and I have been very happy with this method.
I can get 'near enough' by setting a pressure, then looking for the view.
Not having done a side by side with a Lunt tilt tuned, I cannot compare.
It is easy to put a camera on the LS60.
I have suffered a cloudy blue filter. 10 minutes to swap out with little skill and very affordable.

I have never used any of the Quark offerings.
I was put off buying by the quality issues being reported about 4 years back when I was considering upgrades from the PST.
Intuitively I'm not that keen on the idea of a heated etalon.
It has to be slow to respond and a thermistor/control problem is another point of failure that can't be fixed by a DIYer.
There are complete Daystar scopes for less money than the Quark eyepiece. I'm sure these have to use the bottom grade etalons.
However, there are happy users out there.

This year for white light I spent on a Lacerta Herschel wedge & solar continuum filter, on a 2nd hand 102mm achro. A lot less than Ha spend!
Great results in white light. Lots to see with the sun being very active at present. Very quick to set up.

Sorry, no easy yes/no answers. But keep looking and asking.

HTH, David.

 

[Elp]

3 hours ago, raadoo said:

Quark, nor the entry level offerings from Lunt or Coronado/Meade are long term scopes

For clarification the quark can be used with any refractor telescope. If you've got the budget for it though Lunt tends to be the one most people want or go for.

[raadoo]

9 hours ago, michael.h.f.wilkinson said:

I hav eimaged with a humble Lunt LS35 THa, a Coronado SolarMax-II 60 mm,  and an APM 80mm  F/6 triplet with ERF, Baader TZ-4 4x tele-centric Barlow, and a Solar Spectrum 0.3 Å H-alpha filter. In the latter I could only image parts of the sun and needed to stitch the result. The differences between the set-ups can be seen below (click for full size view)

If you can get something like a secondhand LS50 or 60, or a SolarMax 60, that would be a great start.

Thanks so much for taking the time for such a comprehensive reply! One hears (and reads) a lot about how aperture is king but in reality, I'd be happy even with the results you got from the LS35. I have seen a used SolarMax II 60mm BF10 available but I'm slightly put off by the potential rusty ITF issue. However, I am not one to shy away from a bit of tinkering so if need be I think I could probably replace the filter if and when it rusts over. It's available from a retailer I've dealt with before so I should be able to RMA it if it's a faulty scope. Alternatively, I could do a bit of saving and get a new LS50 and, in time, replace the focuser (reportedly the worst part of this scope) and, later still, double stack it.

[raadoo]

9 hours ago, Carbon Brush said:

I used to own a PST. As a place, point, look instrument, it was good.
Just focus then twist the etalon to see if there is anything to be seen today.
As others have reported, adding a camera to the PST was at best a faff and realistically quite a clumsy affair.

These days I get my Ha fix from a Lunt LS60. Which gives better views than my PST did.
Caveat. Performance of individual Ha scopes does vary.
The Lunt is heavier so more demanding of the mount.
I run it on a Solarquest mount, taking care with balance.
It is the pressure tuned version and I have been very happy with this method.
I can get 'near enough' by setting a pressure, then looking for the view.
Not having done a side by side with a Lunt tilt tuned, I cannot compare.
It is easy to put a camera on the LS60.
I have suffered a cloudy blue filter. 10 minutes to swap out with little skill and very affordable.

I have never used any of the Quark offerings.
I was put off buying by the quality issues being reported about 4 years back when I was considering upgrades from the PST.
Intuitively I'm not that keen on the idea of a heated etalon.
It has to be slow to respond and a thermistor/control problem is another point of failure that can't be fixed by a DIYer.
There are complete Daystar scopes for less money than the Quark eyepiece. I'm sure these have to use the bottom grade etalons.
However, there are happy users out there.

This year for white light I spent on a Lacerta Herschel wedge & solar continuum filter, on a 2nd hand 102mm achro. A lot less than Ha spend!
Great results in white light. Lots to see with the sun being very active at present. Very quick to set up.

Sorry, no easy yes/no answers. But keep looking and asking.

HTH, David.

 

Even for someone as new to solar astronomy as I, the PST always looked more like a visual tool, rather than for imaging, even with potential upgrades. From what I've seen around the forums, the most use imagers get out of a PST is to cannibalise its etalon and then Macgyver it onto a doublet. And while that's well within the realm of many an SGL'er, the consequences of getting something wrong are far too disastrous and permanent for me to attempt. i.e. I'm quite fond of my eyes and would like to keep them going for as long as I can. 

For once, the mount isn't going to be an issue with me, as my mount can easily move an 8" SCT / 5" APO; the kind of solar scopes I can afford are nowhere near that kind of payload.

I'm also quite nervous about the whole Quarks need time to heat up. Not necessarily because of wasted time - thought that's definitely going to get old real fast - but more so because electronics will generally break long before analog mechanisms do.

The Achromat + Herschel + Solar Filter route is definitely something I've considered and seems to be the most cost-sensitive option for high quality safe solar imaging and viewing. Trouble is I've got this annoying condition of being in love with Ha 😆

[raadoo]

Thanks to everyone who replied, I've narrowed it down to two options (for now, at least):

1. €1400 New LS50 B600 - with later upgrades including the focuser and double-stack filter
2. €1800 Used SolarMax II 60mm BF10 - with possible replacement of the ITF if and when it rusts

Keen to get your thoughts on which is a better choice.

[Pete Presland]

I don't think you will go far wrong with the Lunt 50mm, the upgrades are a great improvement particularly double stacking. 

No point in getting a lunt 60 and double stacking that, as you will back down to 50mm aperture.

[Elp]

Personally I'd go for the new one as at least you'll have a warranty for some piece of mind. I'm sure you'll be very happy with it.

Fyi once you know how to do it the PST is actually fairly easy to image with.

[newbie alert]

3 hours ago, raadoo said:

Even for someone as new to solar astronomy as I, the PST always looked more like a visual tool, rather than for imaging, even with potential upgrades. From what I've seen around the forums, the most use imagers get out of a PST is to cannibalise its etalon and then Macgyver it onto a doublet. And while that's well within the realm of many an SGL'er, the consequences of getting something wrong are far too disastrous and permanent for me to attempt. i.e. I'm quite fond of my eyes and would like to keep them going for as long as I can. 

For once, the mount isn't going to be an issue with me, as my mount can easily move an 8" SCT / 5" APO; the kind of solar scopes I can afford are nowhere near that kind of payload.

I'm also quite nervous about the whole Quarks need time to heat up. Not necessarily because of wasted time - thought that's definitely going to get old real fast - but more so because electronics will generally break long before analog mechanisms do.

The Achromat + Herschel + Solar Filter route is definitely something I've considered and seems to be the most cost-sensitive option for high quality safe solar imaging and viewing. Trouble is I've got this annoying condition of being in love with Ha 😆

The lunt is only a achromat

Yes you can cause irreparable damage to your eyes/ camera if you don't follow caution... But then again you can by just staring at the sun..

[newbie alert]

3 hours ago, raadoo said:

Thanks to everyone who replied, I've narrowed it down to two options (for now, at least):

1. €1400 New LS50 B600 - with later upgrades including the focuser and double-stack filter
2. €1800 Used SolarMax II 60mm BF10 - with possible replacement of the ITF if and when it rusts

Keen to get your thoughts on which is a better choice.

The possibility of the ITF rusting is no hardship to replace2 versions you can use..

Maier or Beloptik

   https://maierphotonics.com/

[niallk]

I'm visual only, but love my LS50DS w/BF600 + the Moonlight focusser upgrade.

I was worried before purchasing about the cloudy filter issue... and recently had that problem despite careful storage with dessicent.  Ive had the scope 4.5 yrs.  I really needn't have worried: €20 and 5mins to easily replace with a new one - arrived within a couple of days of ordering from Bresser no fuss to replace.

I bought mine at a discount from FLO: customer return - full warranty and checked by the staff beforehand.  I love it

One point for theLS60 is increased focus adjustability- for visual, it will permit binoviewing - whereas the LS50 doesn't for standard BVs.  Cannot comment re imaging!

[newbie alert]

9 minutes ago, niallk said:

I'm visual only, but love my LS50DS w/BF600 + the Moonlight focusser upgrade.

I was worried before purchasing about the cloudy filter issue... and recently had that problem despite careful storage with dessicent.  Ive had the scope 4.5 yrs.  I really needn't have worried: €20 and 5mins to easily replace with a new one - arrived within a couple of days of ordering from Bresser no fuss to replace.

I bought mine at a discount from FLO: customer return - full warranty and checked by the staff beforehand.  I love it

One point for theLS60 is increased focus adjustability- for visual, it will permit binoviewing - whereas the LS50 doesn't for standard BVs.  Cannot comment re imaging!

Lunt have been known to honour the warranty and have replaced the ITF foc... Shipped from bresser direct

[raadoo]

1 hour ago, newbie alert said:

The lunt is only a achromat

Yes you can cause irreparable damage to your eyes/ camera if you don't follow caution... But then again you can by just staring at the sun..

Being interested in the very narrow band of H-alpha (with a mono camera) means I don't need to worry about it being an achro. In that setup, the benefits of an apo or triplet would be totally lost, unless I'd plan to use it for night time imaging (which I don't).

[niallk]

2 hours ago, newbie alert said:

Lunt have been known to honour the warranty and have replaced the ITF foc... Shipped from bresser direct

Ya, not for me, and I did contact them... slightly miffed, but over it 😉

[michael.h.f.wilkinson]

I have the SolarMax-II with a BF15, and it is great for visual and pretty decent for imaging. A bigger blocking filter is also advantageous in imaging, I find. So regarding the bigger aperture and bigger blocking filter, the Coronado wins. The downside of that instrument (which is why I am eyeing a potential replacement is the central obstruction of the etalon, which makes the Lunt a slightly more comfortable scope visually.   I also have a 60 mm Double-Stack unit, which greatly increases contrast, at the expense of a much lower brightness. The helical focuser is also not much to write home about. It does the job, but is a bit fiddly. The focuser on my LS35 was slightly better.

Hope this helps

[michael.h.f.wilkinson]

4 hours ago, Pete Presland said:

I don't think you will go far wrong with the Lunt 50mm, the upgrades are a great improvement particularly double stacking. 

No point in getting a lunt 60 and double stacking that, as you will back down to 50mm aperture.

There are Lunt 60mm aperture Double Stack units: https://www.teleskop-express.de/shop/product_info.php/info/p4958_Lunt-Double-Stack-Etalon-for-all-LS60FHa-Filters-and-LS60THa-Telescopes.html

[Pete Presland]

Thanks for the correction @michael.h.f.wilkinson i never knew that existed.   I always thought it odd that you would buy a 60mm aperture, only to have to reduce it to 50mm when double stacking.

An eye watering price though, has this been around very long ?

[inFINNity Deck]

2 hours ago, michael.h.f.wilkinson said:

So regarding the bigger aperture and bigger blocking filter, the Coronado wins.

Lunt supplies blocking filters of various diameters, especially for imaging with large and even larger sensors: https://luntsolarsystems.com/product/lunt-blocking-filters-b600-b1200-b1800/

Scroll down to the section "Focal Length Suggestions for Imaging Use:". Of course a larger blocking filter is more expensive. Most, if not all, are also available in straight-through version (i.e. not as diagonals).

Nicolàs