New Lunt modular solar scope triple stack

[GavStar]

Solar observing has definitely played second fiddle to night time observation for me since I started this hobby in 2012. However as I’m now working from home all the time and my young daughters are at school, suddenly I have time during daylight hours for some solar viewing.

Even though there hasn’t been much solar activity in the last few years I’ve had some really nice views recently with my lunt 60mm tilt tuned double stacked setup. Even better when used with my Baader mark v binoviewers.

However, this setup does have a relatively small sweet spot and it got me thinking about upgrading. I have previously considered the lunt 80 or lunt 100 but the 80 doesn’t have an external ds unit available and the 100 appears to struggle with Uk seeing conditions. In addition, I really like the portability of my solarquest mount which wouldn’t support the 80 or 100 and I prefer full disk viewing than higher mag stuff.

The recently launched lunt 60mm modular setup gave an opportunity I thought to get a setup that had a much bigger sweet spot by using it with the internal etalon removed and two external double stack unit screwed into the end. In addition, with the internal etalon in place it would give the opportunity of a possibly higher contrast triple stack view of the solar surface.

I took the plunge and today the 60mm lunt modular and additional 60 ds unit arrived from telescope house. Conditions weren’t great but there was about an hour or so of decent viewing around lunchtime.

First up was removing the internal etalon and going for 2 external 60mm Etalons screwed the the end of the modular scope. My solarquest mount handled this setup fine and the views were exquisite. Lovely detailed full disk views at 40x with a massive sweet spot. A definitive step up from my previous double stack setup. Even in single stack mode there was plenty of surface detail visible.

Then I reinstalled the internal pressure tuned etalon for a triple stack setup. The conditions were getting a bit iffy by now unfortunately but it was clear to me that there was another good step up in surface contrast with the dark elements of the surface really popping up much more obviously than in the ds mode. Also the views were pretty bright despite the triple filtering.

A good first go but I’m hoping for some more sunny spells this week to try it out further (some more solar activity would be good as well!)

Here’s a pic of the setup today - very portable.

Edited October 5, 2020 by GavStar

[Captain Scarlet]

5 minutes ago, GavStar said:

... working for home all the time ... daylight hours ... solar viewing...

are you a professional solar viewer ?

[vineyard]

That looks intriguing @GavStar, looking fwd to hearing more & seeing some images hopefully.

Was wondering if I could ask a quick Q pls?  Would you be able to share what the length of just the OTA is?  I'm going to hazard a guess that its around 275-280mm but can't see that in their manual.

Reason for asking is that I have an FPL-51 f6 refractor (72mm aperture) and was just tinkering to see if I could get it to work by putting my Lunt50 on the back-end - like I am able to w my 4" frac.  And that franken-setup doesn't quite find focus in the 72mm although it does in the 102mm.  Which was puzzling me until I remembered what @Merlin66had mentioned when I was doing my original 102 solar-mod tinkering.  Namely that w a Lunt50, the etalon needs to be around 140mm in from the prime focus point.  Which unfortunately I'm j-u-s-t a few cm short of in my 72mm...

So I'm curious if that Lunt60MT OTA is a slightly shorter than normal one to allow that etalon to be 140mm in from the OTA's 420mm focal length.  I suspect that might be the case b/c their manual also interestingly says that for night-time viewing, 2" diagonals should be used and that if 1.25" diagonals or cameras are to be used then extensions are needed (which would be consistent with a slightly short OTA and only so much travel available on the focuser?)

Anyway, I figured instead of continually guessing, I'd just ask 

Cheers & looking fwd to seeing what a triple-stacked image looks like!

Vin

[Highburymark]

Nice one Gavin. Very interesting journey you’ve been on that you’ve had better results from your 60mm Lunt than Solarscope 70mm filters. Not often that happens, but looks like you’ve got a cracking set up now. Must be pretty good if you could get decent views yesterday when the Sun was so bland - sign that the bandwidth will deliver great contrast when we get more activity.

Keep meaning to try triple stack with my Quark and SF70 filters, but not convinced it’s going to be bright enough.

To jump in and answer Vin’s question - despite being a dab hand with his mobile phone camera and night vision system, Gavin doesn’t do solar imaging. 

[GavStar]

@vineyard I’ve just measured the ota and it’s 23cm without focuser or internal etalon, 29cm with focuser no etalon, and 33cm with focuser and etalon. As Mark says I’m visual only for solar but maybe one of my local club members such as @PeterW may have a go at some imaging in triple stack mode at some point.

@Highburymark Yesterday I initially tried the new modular scope in single stack mode with just one external etalon (and having removed the internal etalon). Even in this single stack mode the surface detail was good across the whole disk, the best detail I’ve seen from a single stack setup including the Solarscope 70mm filters I had. This got me pretty excited to add the extra external etalon for full external double stack mode and I wasn’t disappointed 😀

The triple stack mode showed nice areas of darker activity that were not clear in double stack mode. So even with a bland sun there’s still plenty of stuff to look at. Very much looking forward to when ‘proper’ activity starts. After a bit of experimenting I think I’ve found the perfect setup for my particular visual solar preferences. I prefer keeping to lower magnifications say max 50x but I know Mark you’ve had great success with much higher mags with your new Solarscope setup. I didn’t get to try my Baader Mark v binoviewers with this setup yesterday - hoping that those deliver even better results. I like it that I can reach focus with my gpc 1.7x rather than have to use a 2.6x gpc. My pan 24s with the gpc 1.7x are lovely.

Edited October 6, 2020 by GavStar

[Nigella Bryant]

I love my Lunt 60mm DS. Never thought of triple stack but interesting. Thanks Gav. Here's what I'm getting in DS. 

[vineyard]

5 hours ago, GavStar said:

@vineyard I’ve just measured the ota and it’s 23cm without focuser or internal etalon, 29cm with focuser no etalon, and 33cm with focuser and etalon. As Mark says I’m visual only for solar but maybe one of my local club members such as @PeterW may have a go at some imaging in triple stack mode at some point.

Thanks @GavStar - wasn't too far & that's good to know.  I'm going to try a tweak to my Lunt 50 mod with a GPC in the optical train in front of the etalon to try and be able to position the etalon 140mm in from the adjusted prime focus.  Let's see.  I love seeing the amazing images that folks post (such as the one @Nigella Bryantdid above) so I'm trying to see how much I can tweak my setup vs reconciling myself that there's an upper limit to what you can mod to w a Lunt 50 😂).

Intrigued to see the thread b/w you and @Highburymark above about the Lunt 60 vs Solarscope - I was under the impression that Solarscope etalons were hands down in a better league?

Cheers all

[PeterW]

@GavStaris NOT an imager, I have tried convincing him to add a high frame rate camera.... no luck. Can’t wait to see the views that scope gives.

peter
 

[Highburymark]

18 hours ago, vineyard said:

 

Intrigued to see the thread b/w you and @Highburymark above about the Lunt 60 vs Solarscope - I was under the impression that Solarscope etalons were hands down in a better league?

Think this just re-emphasises the variability among all solar manufacturers’ products. Normally I would expect Solarscope to outperform everything else on the market. Certainly I’m very happy with my SF70DS filters (after previously owning two double stack Lunts - 50 and 60 - both of which were excellent, but the SF70s are a real step up). Most obvious benefits are greater contrast on surface features, bigger sweet spot, and ability to go up to 120x while retaining sharp views. Gavin’s experience is different. From his reports it sounds like his Lunt etalons are extremely good. Others on this forum (Brian - Solar B in particular) have had real problems with Lunt filters - disappointing bandwidth and finesse producing washed out surface views. It is really luck of the draw what you get - and that certainly applies to Coronado and Daystar too. 

[Nigella Bryant]

3 hours ago, Highburymark said:

Think this just re-emphasises the variability among all solar manufacturers’ products. Normally I would expect Solarscope to outperform everything else on the market. Certainly I’m very happy with my SF70DS filters (after previously owning two double stack Lunts - 50 and 60 - both of which were excellent, but the SF70s are a real step up). Most obvious benefits are greater contrast on surface features, bigger sweet spot, and ability to go up to 120x while retaining sharp views. Gavin’s experience is different. From his reports it sounds like his Lunt etalons are extremely good. Others on this forum (Brian - Solar B in particular) have had real problems with Lunt filters - disappointing bandwidth and finesse producing washed out surface views. It is really luck of the draw what you get - and that certainly applies to Coronado and Daystar too. 

I think that's true, fortunately I've got a good Lunt DS, but I've heard and read others have struggled to get anything decent from them. Problem is, you don't know until you've parted with your hard earned cash. There really should be better quality control considering the cost of these scopes. I'm not going to be parted with mine anytime soon, lol. In fact this thread had intrigued me to think about another filter for triple stack, but again, will I get a good one or not?. Another question. 

[Highburymark]

8 hours ago, Nigella Bryant said:

I think that's true, fortunately I've got a good Lunt DS, but I've heard and read others have struggled to get anything decent from them. Problem is, you don't know until you've parted with your hard earned cash. There really should be better quality control considering the cost of these scopes. I'm not going to be parted with mine anytime soon, lol. In fact this thread had intrigued me to think about another filter for triple stack, but again, will I get a good one or not?. Another question. 

Worth checking out solarchat Nigella - where members have been experimenting with triple stack for ages. All about light throughput and compatibility of filters. From the images you’ve posted recently I don’t think you’re in need of any extra help. 👌

[Nigella Bryant]

1 hour ago, Highburymark said:

Worth checking out solarchat Nigella - where members have been experimenting with triple stack for ages. All about light throughput and compatibility of filters. From the images you’ve posted recently I don’t think you’re in need of any extra help. 👌

Thanks, I was just wondering, lol. As you say, probably not needed as I've got a really good DS. 

[GavStar]

After all the cloud and rain recently, I managed to get another opportunity with this new Lunt setup. This time I stayed in double stack mode using the two front 60mm etalons and removed the pressure tuned etalon. I also used my baader mark v binoviewers instead of mono mode (which I didn't use in my previous outing). As noted in another thread today, there is plenty to see at the moment including a massive multi stranded prom to one side, another nice prom on the top, a nice dark sun spot and several other areas of good surface activity. With my 24mm panoptics and 1.7x gpc (nice thing about the Lunt diagonal is that I can attach the binoviewer direct to it and so can use the 1.7x gpc rather than the 2.6x gpc, giving a greater range of magnifications with my eyepieces) I was at about 30x mag, but could easily go higher.

The live visual views fantastic, the best solar views I've ever had and nice and bright despite the double stack and binoviewers. The large prom is amazing with great detail shown by the lunt, I wonder if the ed doublet glass is helping here? The whole disk was in band as well due to the use of two external front etalons so I could relax and let my eyes drift around all the surface soaking in the views until unfortunately I had to pack up to do some work.

Edited October 22, 2020 by GavStar

[Davey-T]

Been having a look this morning, had to cover up quickly for short shower, taking a few pic's now.

Dave

[Nigella Bryant]

Cloud here😭

[GavStar]

I’ve had a six month break from solar but this week had a good opportunity to use this setup again. This time I installed the telescope express adapter between the two front mounted filters. This enabled me to fine tune the setup by “clocking” the two filters. The views were even better with the surface detail and contrast noticeably enhanced in double stack mode with two external filters. I did try triple stack again by adding the internal pressure tuned etalon but although contrast was good, I thought the detail wasn’t as sharp or even across the disk and of course the views were noticeably dimmer. Going forward I’m going to stick with just the two front mounted filters and not bother with triple stacking. The views in double stack mode with Mark v binoviewers are just incredible.

I also tried just single stack with one front filter and this gave excellent fine detail on proms and still showed a good amount of surface detail, much better than the 70mm Solarscope setup in single stack mode that I had.

So @Highburymark how about a shootout between your Solarscope 70mm DS and my lunt ED 60mm front mounted double stack? 😃

Picture of the lunt setup in “clocked” mode below.

[Solar B]

I attempted a Lunt Triple stack in 08 with an LS60 and two 50s (no external 60s back then) and of course it didn't work (posted on CN at the time), as I recall an Andy Denvy did often "very" successfully image with a rare Coronado/Solarscope 100/90/90 crossover triple stack , again on CN some 10yrs ago from memory , more recently on here I tried a 60,60,40 Coronado with some more success than the Lunt , I'll try a 60mm triple as soon as conditions allow in Scotland 🌞

I think that factory matched DS scopes & filters perhaps more recently ? do tend to preform much better in DS mode than SS  meaning that they appear to be heavily set or weighted toward DS views and my recent experiences concur.

But Lunt v Solarscope 😅

Brian 

 

Edited April 2, 2021 by Solar B

[GavStar]

16 minutes ago, Solar B said:

I attempted a Lunt Triple stack in 08 with an LS60 and two 50s (no external 60s back then) and of course it didn't work (posted on CN at the time), as I recall an Andy Denvy did often "very" successfully image with a rare Coronado/Solarscope 100/90/90 crossover triple stack , again on CN some 10yrs ago from memory , more recently on here I tried a 60,60,40 Coronado with some more success than the Lunt , I'll try a 60mm triple as soon as conditions allow in Scotland 🌞

I think that factory matched DS scopes & filters perhaps more recently ? do tend to preform much better in DS mode than SS  meaning that they appear to be heavily set or weighted toward DS views and my recent experiences concur.

But Lunt v Solarscope 😅

Brian 

 

I did a side by side of my lunt 60mm DS vs my new Solarscope 70mm double stack (attached to a televue 76) last summer and unfortunately the views through the Solarscope setup just wasn’t as good as the lunt. The Solarscope filters went back to the Isle of Man to be adjusted but even when they came back the setup wasn’t performing as I wanted. Just goes to show how difficult it can be to get these filters performing optimally. I’m very keen to check out Mark’s Solarscope setup (which is virtually identical to mine) as I know he is extremely happy with his.

[Highburymark]

It would make an interesting comparison Gavin, no doubt. The two most obvious improvements I found going from an LS60DS (with one internal etalon) to SF70DS were greater contrast of surface detail, and the ability to ramp up the power while retaining sharpness. I’ve recently picked up a pair of 11mm Delites for high power solar and lunar binoviewing. With the Zeiss ‘Apo’ binoviewer and 2.6x gpc, I can go up to 140x with the Solarscope filters, which seems crazy, but it works. However, I need very steady seeing, so is only usable maybe once every 5-6 sessions. I wouldn’t be surprised if your Lunt delivers equally great views though.

Hopefully before too long I’ll be able to start imaging with my scope as I’ve just ordered a ZWO asi1600 - just need to sort out a laptop and learn from scratch the capturing, stacking and processing system now. Simples.

[Highburymark]

3 hours ago, Solar B said:

 

I think that factory matched DS scopes & filters perhaps more recently ? do tend to preform much better in DS mode than SS  meaning that they appear to be heavily set or weighted toward DS views and my recent experiences concur.

 

 

A particularly interesting point you make Brian, and my experience also chimes with this.

[GavStar]

15 minutes ago, Highburymark said:

A particularly interesting point you make Brian, and my experience also chimes with this.

@Highburymark do you mean that in single stack mode your Solarscope setup shows limited surface detail? What about proms? Are they better in single stack or double stack?

[Highburymark]

Yes - I was referring to limited surface detail in SS. Proms are sometimes best in SS and sometimes in DS I find. Another quirk - I generally prefer a single eyepiece for proms over a binoviewer.
On Brian’s comment: I remember reading an academic paper elsewhere on the web a while ago on the practice of matched etalon tuning which made the same point. Will see if I can track it down.