Lunt Ls50THa

[jabeoo1]

Lunt LS50THa Review

 

The Lunt LS50THa telescope is my first solar scope. It is also my first refractor. I am using it on the older model 'Vixen Porta 2' mount via a Lunt dovetail plate. The scope has the addition of a Televue sol finder.

From Transit

The package arrived well protected. The outer box contained a second box surrounded by loose foam infill. The inner box contained firm foam which was shaped to hold the contents very securely. Both boxes were tape sealed with Lunt logo tape. I assume it was factory sealed in the USA and remained untouched until arrival. This firm foam could easily be removed and if slightly cut (1cm off either side) it could fit into a 'standard' hard case for a cheap long term solution for transport and safe storage.  So far I am not aware of an official Lunt case for the 50mm model.

First Impressions & Setup

Read the instructions first ! There is a useful piece of information advising that you check the diagonal is secure by checking if the screw on the side of the focuser is finger tight before removing the scope. The risk of the B400 or B600 blocking filter falling off and breaking does not bear thinking about. Do not get too excited and make this mistake !

The scope feels compact but substantial and weighs 2.15 Kg without an eyepiece. The helical focuser moves with a nice resistance as does the pressure tuner (a tiny amount of play on the helical focuser is present but this does not cause any issue in use). The heavy metal dust cap that covers the front lens has a long thread and feels reassuring to take off and replace. All glass surfaces were spotless on inspection after removal from the box.

I realized pretty quickly I would have to loosen the clamshell and turn it 90 degrees to allow correct orientation to the mount. This was easy to do, as was attaching the dovetail plate and sol finder.

In Use

I have done around 4-5 hours observation time so far with the following eyepieces:

 

Televue 25mm Plossl (x14)

Televue 15mm Plossl (x23.3)

Televue 11mm Plossl (31.8)

Takahashi LE 7.5mm (x46.6)

I noticed that to get sharp focus with the TV eyepieces, adding the supplied adapter between the focuser and B600 filter achieved it perfectly.

The scope is very intuitive to use with the information from the short instruction manual.

The sol finder was exactly aligned on first attempt and captured the sun in the 25mm EP, no tinkering needed. The helical focuser when turned produced a sharp limbed disc. The pressure tuner then bought out extensive detail of both disk and prominences, and a quick fine tune back on the helical focuser produced a sharp and pleasantly detailed image.

 

Seeing a hedgerow prominence for the first time was an outstanding start, and I was very satisfied with the ability to get a very sharp contrasted view. Different levels of density were really obvious, as was the changing state of the prominence. As the sun moved across the FOV I noticed that the prominence had the tendency to fade. With higher magnification this phenomenon is less obvious and is not present at all in the 7.5 mm @ x 46.6. Major features at lower power seem to benefit from placement within a 'sweet spot' in the field of view, especially if your aim is to tease out every last detail of that particular feature. This is in no way distracting and is no doubt part of the systems characteristics. Part of the charm is learning the knack of keeping the focus, the pressure tuner and FOV parameters in check to the feature/s you are trying to observe.

 

Scanning the solar limb once tuned to any prominence is great fun, especially as many more become apparent that may have been overseen completely. The pressure tuned etalon in use here is rewarding at bringing out the fullest potential of the morphology of the prominences.

 

With both the pressure tuner and focuser set, I found the 15mm did a lovely job of presenting a nice view of both limb and disc features at the same time. Only a little tweaking of the slow motion controls on the tripod to maintain the view or vary it slightly was needed. Quiet filament regions are presented well along with the sometimes subtle but lighter associated filament channels. Active regions also feature well. Sunspots appear very dark and sharp. With patience all features become more evident in complexity. The only thing I can compare the views to is to imagine viewing a very dynamic Jupiter on steroids in excellent seeing. All this said with the Sun currently in winter placement I have not yet had the opportunity to release the instruments full potential.

[Qualia]

imagine viewing a very dynamic Jupiter on steroids in excellent seeing....

Excellent review, Jabe and thank you for putting this together. Indeed, I think it is the first proper review I've read on the web since the Lunt 50mm has come out and I'm really happy everything things seems sorted out of the box without any quality control issues to contend with. The Lunt 50mm really sounds a great scope and all things considered, for H-alpha viewing is very reasonably priced.

I've seen some images of the 50mm double stacked and it has provided quite stunning views and now reading through your review, I wonder if the pressure tuner is also making a significant improvement on the more traditional tilt design? If this were so, might not the 50mm give the 60mm entry scope a good run for its money? 

Thanks again for your time and effort

[Luke]

Sweet review! It answers a few questions I had on the Lunt 50, very helpful, thank you!

Congrats on first light! You are just gonna love summer, but I think you already know that

[Pig]

Jabe,

Excellent report and I am pleased you are enjoying your new scope

As mentioned by Luke the summer sun can be breath-taking at times so I am sure you will get even more enjoyment from it. However, the winter sun does have a lovely burnt orange colour.

I find the best results I see are when I am using a 9mm eyepiece and from your report the 7.5mm, considering the difference in focal lengths of our Lunt's we end up with around 50 x magnification as the optimum view. This demonstrates a consistency between the two models which I find reassuring

[jabeoo1]

I've seen some images of the 50mm double stacked and it has provided quite stunning views and now reading through your review, I wonder if the pressure tuner is also making a significant improvement on the more traditional tilt design?

The etalon surfaces inside the cavity remain at the same optimal angle and no moving internal surfaces are present,  its the air pressure changes that change the refractive index of the air which allows the tuning.  This could have clear advantages over mechanical springs and wheels where slick moving parts are essential to the tilt design.  I also read that the pressure design has the ability to tune - or + of the hydrogen alpha center line rather than in the case of the tilt design only + of the center line.  I am assuming this means being able to view in both the blue and red 'wings' as apposed to just the blue wing (I may be wrong and need correcting here though).  Viewing in the wings allows the scrutiny of lower chromosphere features or a feature that is doppler shifted that would otherwise be invisible on band.  It should be remembered that as with Ca-K systems we are viewing the chromosphere.  In Ha we are actually observing into a region thats around ~1700Km thick.  The deepest of this region starts ~100Km above the photosphere.  Ca-K allows observations into a region that starts ~400Km above the photosphere with a 'height' advantage over Ha viewing to ~2000Km peak.   

If this were so, might not the 50mm give the 60mm entry scope a good run for its money? 

I only wish I had the opportunity to look into a larger aperture Ha of Ca-K scope !  Imagine what the Lunt 80, 100 or 152 would show

The 60mm sounds like a beauty, the viewing reports sound sublime.  But I found the price tag a bit to high for me given that I am a novice at all this solar stuff !  The 50mm shows plenty to have potential for a long, long time.  I do want to double stack it at some point soonish, which will no doubt make it even more impressive.  

Thanks again for your time and effort

No Problem !

[spaceboy]

Great report and thanks for posting it.

There have been several reports on CN regards slop in the focuser. It would appear this is going to be the case with all the LS50's then

[michael.h.f.wilkinson]

Great report of what sounds to be a great little scope. VERY much tempted to get one as replacement for the little LS35 I have.

[jabeoo1]

Great report and thanks for posting it.

There have been several reports on CN regards slop in the focuser. It would appear this is going to be the case with all the LS50's then

Regarding the focuser:  I will try and explain the 'play' or 'slop' slightly better !

The point at which the focuser is moved from any current rested position I experience a very tiny free movement that does not influence the focal length of the scope.  This tiny free movement is followed by a resistance which is the focuser engaged for very accurate & smooth course or fine focusing.

When the focuser is left there is no slop, its tight where its been left.  Its possible to 'feel' the free movement on the focuser in clockwise and anti-clockwise direction without interfering with the focused image.  Its honestly causes no issue, superficial if anything.  I feel that when reviewing stuff it deserves a thorough scrutiny  

[spaceboy]

Ha you gotta give it to us Brits for having a stiff upper lip approach to things

Thanks jabeoo1 for clearing it up as I was getting the impression from over the pond that everything was loose as  they are sending their focusers back for replacement. I agree if your paying this kind of money you'd want everything to be running like a well oiled machine but I guess our American friends have higher regard for their hard earned than us in rip off Britain.

[jabeoo1]

Ha you gotta give it to us Brits for having a stiff upper lip approach to things

......the impression from over the pond that everything was loose as  they are sending their focusers back for replacement.

Mine is going nowhere except outside as much as possible !

Its perfect tbh

[OneEyedSam]

Nice review...

I believe there is a case sold by Lunt, it takes the packing foam. It's pricey though.

http://www.firstlightoptics.com/lunt-solar-accessories/lunt-case-for-ls35tha-ls50tha-telescopes.html

I'll be ordering one soon hopefully (Xmas hints went over the Mrs head)....

please could you tell me the dimensions of the firm foam, I guess it's just a cm or so smaller than the dimensions quoted in the above link for the official case

Which blocking filter did you get. I'm only interested in visual, so the 400 would do, but thinking if I ever upgraded, that the 600 might aid resale.

[DRT]

Great report and very much in line with my experience of using this scope for 10 months or so. I have had many hours of pleasure watching prominences and surface detail with this scope and had lots of positive comments from many more experienced observers who looked through it during the eclipse at SGL-X.

On the focuser issue, I did find that mine developed more play as time went by and I think that is possibly due to my bad habit of moving the Alt-Az mount by cupping the diagonal/blocking filter in my hand and using it like a lever. The play in the focuser is easily solved by keeping the locking screw relatively tight. Using parafocal eyepieces helps as you can simply get the thing into focus, tighten the screw and leave the focuser alone.

If you get the chance to stick an Ethos 8mm in your Lunt 50 you should grab the chance. I rarely use any other EP in mine now as it knocks the socks off any other EP I have tried with it.

One word of warning about this scope is that it has a very, very small amount of focus travel (10mm, I think) so I have found that lots of eyepieces simply cannot reach focus. I bought the 2" adapter for the blocking filter so that I could use my lower power EPs and have never found a 2" EP that will reach focus.

Despite these minor issues I think this is a great value solar scope and I am really looking forward to the day when the Sun once again rises higher than my neighbour's roof so that I can use it again

[OneEyedSam]

Great to hear the 8mm ethos works so well. is that with the 400 or 600 filter?

[DRT]

Great to hear the 8mm ethos works so well. Assume that gives you the full disk? Is that with the 400 or 600 filter?

Yes, full disk. Mine has the 400 filter. I did ask FLO for advice on which one to buy and they advised the 400 if only intended for visual use.

[OneEyedSam]

Yeah, so what's the hoghest magnification you can usefully go to with the scope, I worked out the 8mm ethos would give about 2.3 degrees of view so the sun will easily fit, would expect to want to use higher magnification too ?

Edit: found this http://stargazerslounge.com/topic/222093-lunt-50mm-solar-scope-eyepieces/

[DRT]

I have used my Ethos 6mm with it but it needs very good seeing. At present that is the highest mag EP I have that would reach focus with this scope so I don't know how far it would go.

[jabeoo1]

I have used my Ethos 6mm with it but it needs very good seeing. At present that is the highest mag EP I have that would reach focus with this scope so I don't know how far it would go.

Agree Derek, 

Seeing is King.  8mm are the big guns on this scope and are really for the perfect times.  It averages out for me to be the 15mm mostly. Saying that, some of the best high contrast & textured full disc views I have enjoyed are with the 25mm.  I use TV plossls in this scope (8mm, 11mm, 15mm, 20mm & 25mm).  For me pushing it to higher magnifications is not necessarily key to enjoying this scope in the UK.  The 11mm is a great compromise between magnification and image scale during average seeing.    

[DRT]

The TV Plossl and Delos EPs all work well with this scope and it really is about getting the clearest view rather than magnification. The beauty of the low power options such as the 25mm and 32mm TV Plossls is that you can sometimes get the full disk in the sweet spot, giving views of prominences all around the disk. With the 8mm I need to move the limb around the sweet spot to see all of the prominences st their best.

[DRT]

Here is a link to the thread I posted when I unpacked mine this time last year: http://stargazerslounge.com/topic/234304-lunt-50mm-h-alpha-unpacked/

It was worth the wait

[OneEyedSam]

Interesting guys, thanks...

[Highburymark]

Agree Derek, 

Seeing is King.  8mm are the big guns on this scope and are really for the perfect times.  It averages out for me to be the 15mm mostly. Saying that, some of the best high contrast & textured full disc views I have enjoyed are with the 25mm.  I use TV plossls in this scope (8mm, 11mm, 15mm, 20mm & 25mm).  For me pushing it to higher magnifications is not necessarily key to enjoying this scope in the UK.  The 11mm is a great compromise between magnification and image scale during average seeing.

I use the Pentax XF zoom exclusively with this scope, which goes down to 6.5mm if I really want to test seeing conditions, but rarely go below 9-10mm when settling on a comfortable high power view. So agree with what's been said.

By the way, the price of the double stack filter has just come down by £200 at FLO. Slightly annoying for those of us who bought one last year, but a more realistic price for everyone else.

[OneEyedSam]

enjoying my lunt 50 so far.  Have bought S/H 11 and 15 TV Plossls. I borrowed a 20 too, but found that wasn't easy to use (my eye had to be on axis to get a fully illuminated view.

Decided not to use my 8 / 13 mm Ethii  given the weight and value hanging off the back....now looking for an 8mm TV Plossl

I put my scope and EPs in a Max 505 case, fitted out with Ethafoam.   Very happy with the set up so far

[DRT]

7 hours ago, OneEyedSam said:

Decided not to use my 8 / 13 mm Ethii  given the weight and value hanging off the back

Neither of those eyepieces should be a risk in terms of weight if the scope is securely mounted. The Ethos 8mm gives a fantastic and relatively high mag view of the whole disk, which an 8mm Plossl will not.

give it a go with the E8

[OneEyedSam]

I have used the 8 (and the 13) with the scope -  the mount isn't the issue, I worry about the BF + EP hanging off that one screw.

 

[OneEyedSam]

hehe, made good use of the 8 ethos over the weekend / Monday.  There was a lovely prom at 4 oclock on the limb.  Got better at tuning too, some really nice detail on the surface.  Need to start sketching !!