Filter recommendation

[Willi1972]

Hi all,

I have recently equipped myself with an EQ5 and ST120, primarily for imaging, as I already do a lot of photography (D7100). My intention was to try my hand at DSOs, as well as lunar and solar. Well, the time has come to start thinking about solar imaging, and the first step is an appropriate filter. I have been blown away by the images of the surface and the prom being posted in the last few days. I saw Starman's images using a Chromosphere and thought to myself that this seemed to give the kind of detail that I was looking for. I duly Googled away and found the appropriate article. I nearly needed medical attention after seeing the price, however. 

OK, so I'm not looking at spending that type of money, but I would like some recommendations for a filter I could use that will still give me some surface detail and maybe a brighter proms.

Any help would be appreciated - as would some clear skies!

Regards

Richard

[Merlin66]

Unfortunately, as you've already found, solar Ha observing doesn't come cheap.

You could consider starting with something like the Lunt 50.

Alternatively there are etalon filters (Coronado SM40/SM60) which could be adapted to your current scopes.

[Pete Presland]

have you considered a 2nd hand PST ?

[Luke]

Richard, when you say "the kind of detail" I assume you want closer up images of the Sun. Really, the Quark is the "cheapest" way to do it in hydrogen-alpha, unless perhaps you go down the route of modding a PST to use with a larger refractor.

So I would say, check out some PST images, and check out some Quark images. If Quark images are much more up your street, maybe save up for it.

I nearly needed medical attention too when I saw the price of the Quark. I was close to fainting at how relatively cheap it was (I say relatively, because, yes, £799 is still a lot of money...). The Chromosphere is rated at 0.3A to 0.5A. To get a 0.5A Lunt 100 dedicated solar scope ("double stacked"), you are talking several thousand pounds...

Solar h-alpha is not cheap, but the Quark is a game changer in my view, making larger aperture solar h-alpha without doing your own mod much more affordable.

Pete also has a SolarScope SF70 filter, I believe. The Widescreen Centre is listing the SF-70 Single Stack Solar Filter System for £4,999.

So I think I am sort of saying, it might be worth saving up for the Quark, when you consider the value compared to other off-the-shelf options.

[Montana]

Mmmm you might struggle as the Quark is the cheapest bar a PST, but then doing the mod also costs more money so the Quark is still cheapest.

Alexandra

[Willi1972]

Thanks for the input. What about the Baader metal film filters? Is this what gives a "white light" image. I'm still trying to get to terms with all the terminology. I have seen some white light images which also show detail on the surface - although nothing like the Chromosphere images. I'm beginning to see the sense in what was mentioned in another thred: having a separate "astro" bank account that the wife does not know about!

And while we're at it, what is a grey light image?

Regards

Richard

[Montana]

Ah I see, we thought you wanted to look at the chomosphere (prominences, filaments, flares, active regions etc). Yes you can buy some Baader solar film for around £20 and make a filter for the front end. You will see the photosphere, so will observe granulation, sunspots and faculae at the edge) see here for an idea of what can be seen  https://www.flickr.com/photos/alexandra4/sets/72157628535703357/

Grey light, well, Steve claims he has a cloud filter and can image the sun through cloud, but no-one believes him

Alexandra

[DrRobin]

Hi,

I started with Baader solar film to take the sun in white light (grey just recently). I couldn't believe how interesting it was and soon bought a second hand PST, followed by a Lunt 60 DS when I wanted more detail. More recently I have added a Quark, but found it quite difficult to get good images. Out of the three I prefer my Lunt, but it is by far the most expensive. Take a good seat, have a stiff drink on hand and Google Lunt 60 Double stack.

If I was you, I would start with white light, Baader solar film and make your own filter. It is very much 'Blue Peter, cardboard and sticky back plastic' but is good fun and you can get some really great results, but you will only see the sun spots and some granulation on the suns surface.

To see the prominences and other surface features you will need a Hydrogen Alpha scope or filter and the lowest cost option is a PST. They can be picked up on the second hand market for around £300. Ha is a very narrow band in the red end of the spectrum and to get the best out of Ha you need a mono camera as the Bayer matrix on colour cameras interferes with the filter and gives dark bands across the image. A colour cam is fine for white light.

I hope this helps, post again if you need any further advice.

Robin

[Willi1972]

Well, I've just ordered some baader film to have a go at making by own filter. Looks like I'm on the slippery slope! All I need now are clear skies.

[Willi1972]

Is there anything in particular that I need to be careful of when Blue-Petering my filter?

[Montana]

Try and follow the Baader instruction guide http://www.baader-planetarium.com/sofifolie/bauanleitung_e.htm

Never make the film to tight in the cell, a bit of sag is absolutely fine, it is better to be too loose rather than too tight.

Make sure the filter is very well secured to the telescope when in use, if it blows off in the wind when you are looking down it, it doesn't bear thinking of.

Other than that and you should be fine

Alexandra

[Willi1972]

Great link, Montana, thanks

[Moonshane]

I use a 1.25" lunt herschel wedge with my 120mm f5 achro. The views are superb in white light. If imaging you may need to get the 2" version though.

[DrRobin]

Hi,

Yes, what Alexandra said, it is great advice. You only get one set of eyes, so make sure there are no holes in the filter and it doesn't fall off the front. That said I am the most risk averse person there is so just follow a few simple rules, make sure everything is right, take your time and enjoy the sun.

Moonshane, I have the 1.25" Lunt Herchel wedge and use it with a web cam. Even with a focal reducer and imaging the full disc, I don't see any vignetting, but don't know if it would be big enough for a DSLR, although it might be just.

Robin

[Willi1972]

Hopefully, my Baader film should arrive today. However, it has just occured to me that I don't need to make a full aperture filter. My photographic background is telling me that the image will be sharper if I just use the central aperture of the scope end cap (ca. 40mm I think). I certainly don't need to gather all the light my 120mm would give me. Would this be a good idea? 

Regards

Richard

[Merlin66]

Richard,

Depending on your local seeing conditions, the "sweet spot" for white light seems to be around 100-110mm aperture.

[Iainp]

Very interesting discussion.

Luke, you raise the issue I've been worrying about: "I nearly needed medical attention too when I saw the price of the Quark... To get a 0.5A Lunt 100 dedicated solar scope ("double stacked"), you are talking several thousand pounds". I bought the Lunt 80mm a few months ago for £3200 and still need to spend another £1700 to double stack it.  Should I have gone down the Quark route, which is 1/5 of the price??  I'm hoping you are going to tell me that there are specific advantages to a dedicated scope like the Lunt, otherwise I seem to have spent thousands more than I needed to for a scope that doesn't (yet) give as good results as an £800 filter.   The medics are on standby awaiting your answer   

[DrRobin]

Iain,

I did a shoot out my Quark v my Lunt 60 DS. The images from the Quark in high magnification were slightly better than the Lunt. However, the Lunt was better at everything else. That is not surprising really, the Quark, on paper at least, should be better suited to that task, high F ratio.

There is a 'but' and for me it swings the balance towards the Lunt.

The Quark excels, but only when the conditions are, or very near, perfect. They have to be to image at close to F/30 and that is the problem we don't often get the type of conditions that are perfect. I would say that the Lunt is a better all rounder, quicker and easier to get the views, capable of some excellent images in a variety of conditions and much faster to use.

Here's the thing, I have had my Lunt60DS for nearly two years, it has been a consistent performer, I bought a Quark to compliment the Lunt, not replace and for the few good days a year it does, but it had 4 weeks back at Daystar until it was right. So, why I am soon going to sell my Lunt60? To purchase a Lunt 80 DS of course.

So I would keep your Lunt80, save up for the DS and then consider a Quark in the future. Unless of course you fancy a swap?

Robin

[Iainp]

Thank you Robin,  that's very helpful and a great relief. The medics are standing down....   .

There were a couple of posts on the forum from people saying they hadn't been able to use their Quarks. Now I understand what they meant. 

Without anything to compare it to, I must say I'm very happy with the Lunt. The view through the eyepiece is consistently sharp and bright, with plenty of detail coming through.  I think I'd still wonder if it was a good investment of £4000+ (I had to get a good motor-driven tripod too) had it not been for the imaging side of things. It's the amount of detail and interest that comes through imaging that has really amazed me, and has got me completely obsessed with the Sun.  Once I've DSed I'll need to talk about upgrading to a suitable mono camera, but that can wait! 

[Luke]

Iain, I have to be honest and say that really your Lunt 80 is a bit useless now, please send it to me double stacked and I'll help out by sending you a Quark :grin:

Seriously, the medics can go home What a lovely scope you have there.

There are some nice advantages to a dedicated h-alpha scope, so much so I am thinking of hanging on to my SolarMax 60 (never mind a Lunt 80), even though we hope to add a second Quark, so we have his and hers. Quite a few plusses and gains, so hard to name them all, but off the top of my head, here are a few:

Dedicated h-alpha scope advantages:

• Shorter focal length. Handy for full disc imaging, or for seeing the full disc or more of the disc at the eyepiece in the larger apertures. I get full disc comfy with my Quark and TV60 and a 32mm Plossl. Quark and ED100, nowhere near full disc with the 40mm Plossl.
• Better contrast by a comfy margin when doudle-stacked. Sweet!
• Possibly more likely you can use your existing eyepieces - I bought 32mm and 40mm Plossls specifically for the Quark, though that said, I have been finding them handy for regular astro too now. Nice and light/compact, handy for travel.
• Doesn't need power. A nice feature on days when you are waiting hours for gaps. No cable to plug in.
• No warm-up time. The Quark needs about 12 mins or so to warm up.

Quark plus points:

• Price. This is the big one. I wanted to get some closer up imaging than was possible with my SolarMax 60. I had been drooling over the SolarMax 90 (though concerned it might be on the heavy side for my HEQ5 mount), figured that I probably wanted a Lunt 100 if going Lunt, considered a Solarscope SF70 as a replacement for the SM60 and a compromise in terms of aperture. The SolarScope SF100 was for when I won the lottery. When push came to shove, I ideally wanted double stacked and budget not much over £2k. So in the end it was Quark or nothing. Quite an easy decision
• Greater resolution (depending on scope, of course). My Quark and ED100, in terms of detail and ignoring the plus points of its rival, frankly destroys my SolarMax 60 double stacked at the eyepiece, despite costing less even if buying the ED100 brand new as well. It is not even close.  It's like me racing Usain Bolt over 100m. As said, that is just in terms of detail - the SolarMax 60 gives a very nice image, no question, but for higher resolution, the aperture wins.
• One scope solution. Can double up as a white light scope, or maybe even treble up if you have something like a CaK module. And at night you can use it for regular astro. Travel with less bulk. This is nice, especially as I take it to work for solar lunch.
• Can be used with different refractors. Pretty handy, so I can match the scope to the needs of the day. If the seeing is a bit suspect for the ED120, I can swtich to my Tele Vue 85. Bit of observing on the Giro mount, I'll take the ED100, thank you. Off to work with the scope for solar lunch, the tiny Tele Vue 60.
• Can be handy when imaging both white light and h-a. No need to take the scope off the mount, just cover over carefully and swap the diagonal for the wedge.
• No obvious sweet spot. With my SolarMax 60, I tend to bring proms closer to the centre when looking at them. With the Quark. proms look just as good to my eyes near the edge.

These are just some of the things. But for me there are enough differences that if budget allows it can be nice to have both.

If anyone is able to afford one only and is wondering if really you need a regular h-alpha scope to partner the Quark, I would say that no you don't need a regular h-alpha scope too, the Quark is perfectily viable on its own. I have barely touched the SM60 since I got the Quark 5 months ago. I think I will try to grab some full discs in one tile now and again with the SM60 as it's likely to stay.

I would be fine with Quark and two refractors - something around 60mm and then I would have a dilemma, ED100 or ED120. The 100 I think I would go for if a bit more visual. If a bit more imaging, I would probably go the ED120.

I originally intended to get the Quark to use with my ED120 as a nice extra to my SM60. I was expecting to use the SM60 the most, and the Quark when conditions were fab. But thanks to the 0.5x reducer (I think I get about 0.55x with it), conditions have almost always been reasonable enough for my ED120. I can switch to 85mm if needs be, or down to 60mm. I have also started playing with 2x binning. If the seeing gets disasterous, I think I will try my 60mm scope, 2x binning and do a mosaic. I imagine it will compare fine to prime focus with my SM60 though I will need four tiles intead of one.

Sorry for all that waffle, I was trying to cover some wider points as well.

Basically, no I don't think you have wasted your money, in a similar way that an SCT is not a waste of money versus a far cheaper dob. They have a number of differences and sometimes you can jusitfy the extra outlay if it suits your needs better and it's in budget. The Lunt 80 wasn't in the race for me, out of my budget simply.

Very interesting discussion.

Luke, you raise the issue I've been worrying about: "I nearly needed medical attention too when I saw the price of the Quark... To get a 0.5A Lunt 100 dedicated solar scope ("double stacked"), you are talking several thousand pounds". I bought the Lunt 80mm a few months ago for £3200 and still need to spend another £1700 to double stack it.  Should I have gone down the Quark route, which is 1/5 of the price??  I'm hoping you are going to tell me that there are specific advantages to a dedicated scope like the Lunt, otherwise I seem to have spent thousands more than I needed to for a scope that doesn't (yet) give as good results as an £800 filter.   The medics are on standby awaiting your answer   

[DrRobin]

Thank you Robin,  that's very helpful and a great relief. The medics are standing down....   .

There were a couple of posts on the forum from people saying they hadn't been able to use their Quarks. Now I understand what they meant. 

Without anything to compare it to, I must say I'm very happy with the Lunt. The view through the eyepiece is consistently sharp and bright, with plenty of detail coming through.  I think I'd still wonder if it was a good investment of £4000+ (I had to get a good motor-driven tripod too) had it not been for the imaging side of things. It's the amount of detail and interest that comes through imaging that has really amazed me, and has got me completely obsessed with the Sun.  Once I've DSed I'll need to talk about upgrading to a suitable mono camera, but that can wait! 

I think I would get the mono camera first.  A DMK41 was the thing to have, but there are a lot of new kids on the block, Luke and others like the Point Grey, but I bought an ASI120MM for night time (mono planets) and it is a really good performer on solar, so much so when the opportunity came to purchase a pre-release ASI120MM-S (USB3.0) version, I jumped at it.  You get a little banding with an ASI120MM but it isn't really any worse than a DMK41 and if you let the image drift around a little during capture then it averages out.

I take 1,000 frames at 60 fps in 1280x960 (8 bit), takes 17 seconds and normally my mount needs a few manual corrections so any banding is soon averaged.  Compare that to my DMK41 which takes at 15 fps max, you see the advantage.  If I run the ASI120MM-S in 16 bit mode it maxs out at 30fps, still twice as fast.

I don't want to knock the Quark, they are actually quite good and I agree with Luke 100%, up to the point of which I would reach for first, that would be my Lunt 60 DS.  When I first got my Quark, it was the new toy syndrome, I used it all of the time and it was only when it went back for re-calibration (attitude adjustment?) that I went back to my Lunt and realised what a great scope the Lunt is.  If I had a Lunt 80 (either SS or DS) I know which one I would be using out of choice.

That said, I took my Quark and white light rig on holiday in the summer, it worked very well and it should be going with me to sunny parts of the world at Xmas, again with my white light rig, I couldn't fit my Lunt in as well and this is the main reason I bought a Quark, as a travel Ha scope and when the conditions are right as a high magnification, high resolution imaging tool. 

Robin

[Iainp]

Wow, thanks for the detailed answer Luke!

That's a lot for me to think about.  It seems I haven't made a bad choice at least.  I don't have a refractor at the moment but we may go to Venezuela (my wife's homeland) for an extended time in the future so having a multi-purpose scope for night and day could be just what I need. 

PS I was in Bedfordshire today, and for a few minutes I saw a bright yellow thing in the sky, presumably the Sun  No such luck in Cambridgeshire for the foreseeable unfortunately 

[Iainp]

Robin, just as I posted the comment about  travelling light, your post came though making the same point!

 Re cameras,  I thought I'd have to spend many hundreds of pounds for a decent mono camera but a quick look online suggests I can get the ASI120MM-S for  £270 which is within budget (if I add up all my projected Xmas money and ignore credit card debts...) I couldn't see a UK price for the point grey (flea 3?) but  presume it's more expensive. 

Any thoughts on whether it's worth waiting till I'm richer to spend more, or should I just go ahead with the  ASI120mm-S now? 

[Davey-T]

 I couldn't see a UK price for the point grey (flea 3?) but  presume it's more expensive. 

Point grey cameras and prices here

Dave

http://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectID=4805286&ViewAction=ViewProduct

[Iainp]

Thanks. Ok, £409 is kind of affordable too. Sorry if I'm going off the forum topic and onto equipment but, shall I:

a) get the  ASI120MM-S? 

  the Flea 3?

c) something else (sub £500)?