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60 vs 80mm Lunt


Sunshine
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The opportunity will present  itself (so my local shop tells me) for me to purchase a Lunt much like the 60mm I once had and foolishly sold. having said that, I am wondering if mainly used for visual would it be a big improvement to have an 80 over a 60?. For night time observing I am aware of how aperture means everything but, on an object like the sun I ask myself if larger aperture is mainly for imaging? I am not sure. 

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I believe the quality/resolution of the detail you see is far greater but as you say, probably more noticable when imaging as you can adjust after imaging to bring out more details. Personally from a Coronado PST, I wish I had a 60mm at least for h alpha solar as my 60mm refractor white light is a pleasure to use.

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28 minutes ago, Elp said:

I believe the quality/resolution of the detail you see is far greater but as you say, probably more noticable when imaging as you can adjust after imaging to bring out more details. Personally from a Coronado PST, I wish I had a 60mm at least for h alpha solar as my 60mm refractor white light is a pleasure to use.

Thanks, my first H-alpha scope was a PST! loved that little scope, it introduced me to H-alpha and I spent countless days enjoying it.

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6 hours ago, Sunshine said:

The opportunity will present  itself (so my local shop tells me) for me to purchase a Lunt much like the 60mm I once had and foolishly sold. having said that, I am wondering if mainly used for visual would it be a big improvement to have an 80 over a 60?. For night time observing I am aware of how aperture means everything but, on an object like the sun I ask myself if larger aperture is mainly for imaging? I am not sure. 

Resolution makes a big difference on solar from a resolution perspective, same as it does at night. If I had the funds and opportunity to buy a Lunt 80 over a 60 I would do it like a shot!

I opted for a much cheaper solution which is a lovely 100mm PST mod which gives fantastic high mag prominence views and decent surface views, albeit not able to show full disk with the binoviewers I use.

I doubt you would regret the 80mm.

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I have 40mm, 80mm, 100mm, 120mm and 150mm Ha telescopes.  Due to high costs, only the 40 mm is a commercial unit, the rest are PST mods.  Regardless of this, a comparison can be made.  As with conventional telescopes, small incremental increases in aperture present small changes in resolution, as resolution increase is linear it takes at least a doubling of the aperture to make a significant improvement visually, the Sun is similar to the Moon in the respect that both look good at almost any aperture.  My 80mm lives in Tenerife, I use my  150mm exclusively here in the UK, both give excellent views on a good day but the larger model provides greater detail and higher magnification, 150x is the lowest available due to the optical layout of the optics to make binoviewing possible, binoviewing the Sun is as beneficial as that to the planets.   😎

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I also doubt that you would regret going with the LS80. I had an LS60 and was torn between upgrading to either the LS80 or the LS100. I went for the 100 and I am still happy with the decision. Beyond an increase in resolution part of my reasoning was that the increase in brightness at the magnifications I typically use would help if I double stack at a later date. I use a binoviewer. 

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With etalons it's not just about aperture, it's about how good the etalons are, with massed produced one's it's a little hit and miss. I've a Lunt 60 DS and fortunately got nice one's but I've also read and seen 80mm that, pardon the pun, don't stack up and people are disappointed. If you've got a really nice 60 I'd get a CaK filter as I've done to compliment the HA with a 100mm refractor unless you've already got that. Although the CaK is imaging only with a cheapish zwo camera what's not to like. Just my thoughts and experience.

Edited by Nigella Bryant
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I saw a modest but very clear resolution improvement going from 50mm to 60mm, and then a more substantial jump going from 60mm to 70mm, where I am today, although the 70mm etalons are higher quality than the 60s I had.  
If you get a good LS80, no doubt you’d see significantly more detail. The only drawback with the LS80 is if you want to double stack, many (all?) owners report an annoying bright shadow around the disc. These can be lessened by fitting another internal filter, but need to be taken into consideration if buying the DS version.

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I'd go for the largest aperture budget allows (assuming equal quality of the filter). I would sort of compare it to viewing the moon. A larger telescope is going to allow you to see more detail at higher mag. More detail in proms and more detail in the swirls surrounding spots. The extra aperture is giving you more resolution, just like with the moon.

Edited by Luke
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  • 3 weeks later...
On 30/09/2021 at 00:17, Sunshine said:

I am wondering if mainly used for visual would it be a big improvement to have an 80 over a 60? For night time observing I am aware of how aperture means everything but, on an object like the sun I ask myself if larger aperture is mainly for imaging? I am not sure.

Short answer is that I don't think you can go too far wrong with either option e.g. Lunt 60 DS or 80 SS, for about the same outlay, but YMMV.

I have a 60 and DS, but used for less than a week. I had the same question e.g. SS 80 or DS 60 for about the same expense, back in February when I placed my order. There are DIY solutions to use smaller etalons with larger optics and there are other options like a Quark on an existing scope. I did spend quite some time and decided that it was better to forgo aperture for DS. Otherwise, I think the DS will be a later addition (I nearly wrote addiction!). I did briefly own a Quark, which had a fault with the main cell - there was a line almost directly across the middle (so much for quality control) and the PSU would give mild electric shocks - worse on damp grass (but it was only mildly irritating and I'm still here). It was returned for a refund along with an expensive UV/IR filter. A secondary disadvantage of the quark (for me) on my 4" scope, was only seeing a partial view of the sun - which I found disorientation and no option to "zoom out". For best operation about F/25-F/30 is required. So, using the objective/EP calculators isn't the whole story. I now others have been through a sequence of Quarks, trying to find a reasonable one, but I simply don't have the patience for this.

The DIY option is something that always exists, although I wouldn't want to do anything that I later regretted. Experience learned the hard way with solar might not be advantageous? The reason that solar scope are so expensive comes down to the cost of making etalons. Using Lunt as an example, doubling the size of an etalon increases the cost roughly 4 times.  A blocking filter and etalon as an addition can be about the same as a whole scope. The blocking filters also increase. On a 60 the sun is about 4.2mm across and in theory a B600 filter would be OK, but in practice a B1200 is better especially for imaging (not tried imaging so far). There are also different focus options that bump up the price. I have the R&P option and don't have (so far) any regrets. I don't have experience of an 80, but the image size is not vastly different, so as the B1200 is more than adequate, I can't see a reason to opt for an 80 with B1800. It may be beneficial because of the DS arrangement, I just don't know.

A 60 DS is different to an 80 DS in that the 60 uses an internal first etalon and a front mounted DS etalon. On an 80 there are two internal etalons. The advantage of the internal etalons is that they can be made with smaller diameters. Like an EP, the telescope resolution is a function of the objective diameter and not the EP or intermediate lenses used. Internal etalons use two additional lenses to spread and converge the light path so that the light passing through the etalon is exactly perpendicular. A disadvantage of two etalons close together is that the second etalon doesn't throw the shadow of the first one away. This effect can be mitigated to some extent with an additional filter, as a mod? The 80 uses the same DS as the 100. So if you feel like upgrading to a 100 you save some money! There is also the option to use a front mounted DS on the 100. Clearly a better option, but realistically, since it's a big piece of glass, it also comes with a 4x price hike. Talking with Lunt, it doesn't seem that popular e.g. only a handful have been sold. Another option is to use a 60 with a 50 DS, but perhaps buying the 50 to use with a 50 DS would yield approximately the same result? Quite popular but it depends on what you want.

Another factor to consider is the weather - aperture matters greatly with night time viewing where photons are in short supply, but for solar, there is an abundance from our neighbourly star, so like solar film and ND filters and wedges etc, brightness isn't an issue. The resolution is a direct function of objective aperture. In theory it is linearly related but it is perhaps a bit more than that. So an 80 should be a bit more than 4/3 improved. I wouldn't be too concerned about aperture because seeing conditions also greatly affect what you see.

I reached the conclusion that there is no short cut (or cost saving) as what you pay (pretty much) determines what you will see. Etalon quality does also greatly depend on which supplier you opt for. In some ways, it is remarkable that you are able to buy a solar scope anyway as it's not the easiest thing in the world to make and there isn't much competition. What you can buy today was also prohibitively expensive in the past and internal etalons have really made that achievable as most folks have budget constraints. Still very expensive, relative to some other parts of the hobby? Etalon quality may also be a factor that is more important than absolute aperture. One reason to buy S/H is that you are often able to "try before you buy".

I have a Lunt LS60MT and 60mm DS with B1200 R&P and no regrets (so far). I haven't needed to "throw in the towel" or use a towel and the image, especially as SS is very bright. The FL is shorter than previously used, now F/7 vs F/8.2 too?  I haven't (so far) converted the scope for white light or night time - it is modular. It is marketed as 60mm but the front objective is a 70mm. There may be a field stop that limits the light path as it passes through the etalon section? I'm just coming to terms with how small the whole setup is. Compared to a 100mm Esprit the weight and size are tiny (a convenient - good thing). I carry an EQ6-R Pro mount into the garden and then attach only one (of two) counterweights. The scope is not unlike a finder (it isn't but seems that way) so is very easy to put on the mount. I also have the Lunt 4" long dovetail - balances very nicely and the DS doesn't upset things. I'm not compelled to swap out the dovetail for a green 6" SW one that I have (somewhere).

I do have a Televue Sol Searcher - arrived from FLO yesterday. Finding the sun isn't so hard without one. Simply set the mount north, key in the sun and it slews almost to the right direction and then using the shadow of the sun shield (4" long black ring on my version) and notice that is is 4mm wider than the body. If you equalise the shadow on the clamshell on two (ideally 4 sides) to also be exactly 4mm (and balanced) and you are looking at the sun in the EP. I have the Lunt zoom, on the widest view the sun fits comfortably and zooming in from there. I can use other EP but the hassle of switching them offsets any potential gain, IMHO. You can of course get lightweight mounts that auto align but I'm happy with a heavier mount (that I already have). Using the PT doesn't affect (move) what you see with the bigger mount, but YMMV. The Sol Searcher is (to me) an interesting/useful addition - pending the lack of clouds we have today, of course.

The previous version of the 60 (also the 80 or 100) were dedicated to solar use. The new modular system provides for other uses. I originally thought this was a gimmick because the cost of doing solar is quite high and most astronomers will come from another setup e.g. already have a larger scope for night time or white light. I am however, coming around to the idea that you want several options during the day e.g. h-alpha and wight light (wedge) or h-alpha and C-aK. Whilst you could use one e.g. AZ mount and two scopes simultaneously to do this, the option to switch over and use one scope and one mount is much simpler, IMHO. I haven't tried it (so far) as you have to swap 6 grub screws for 6 finger screws (provided) and then (others have said) the time to swap over is about a minute. On a 60 the etalon (red part) is removed and the focuser reused with the blocking filter/diagonal exchanged for a white light or C-aK e.g. I will use my BP Herschel Wedge. On an 80 it's similar except an (optional) separate focuser can (needs to) be used. I don't see a need for using the scope for nighttime use because I already have a 4" APO, except that for very wide field it might mean that I can get an even wider FOV with my existing colour camera using the 70 scope. For me, the benefit is the convenience during the day. Lunt do market their new modular scopes as being 0.65 angstrom vs the old 0.70 angstrom. I wouldn't be sure that this isn't anything other than "marketing speak" e.g. taken "with a pinch of salt".

Simon

Edited by SimM
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I’ve said this before, but it bears repeating. At the prices Lunt is charging in the UK, it may be worth considering other alternatives. The current price for a single stacked Lunt LS80, B1800 with Feathertouch focuser (admittedly the most expensive option) is an incredible £7,442. Single stacked!! Why does it cost that much for one, small internal etalon?
So when I was upgrading, I ended up choosing double stacked 70mm Solarscope filters to use with my TV85. These are made to order, matched etalons - external, full 70mm aperture with no obstruction - for only a few hundred quid more than the price of the single stacked LS80 quoted above. Yes, Solarscope products are more expensive outside the UK, and not cheap here, but they are a cut above everything else on the market.
 

197CDC37-E9D0-4448-8554-60B144DD2A59.jpeg

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I should add - get a good LS80, maybe with much more affordable R&P focuser, 1200 blocking filter - and it will be superb. The extra resolution over the 60 will be very noticeable, and perfect for a climate where seeing often limits the benefits of higher apertures. Just a case of finding the right scope.

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Lunt are stupidly expensive, I was looking at the new "affordable" 40mm, local prices are like £850 odd plus shipping for the B500 telescope making the competitive USA $599 price (direct conversion to GBP is £437) non competitive, even with import tax, duties and shipping added it would be much cheaper to source from the USA.

Guess my PST will have to do (though I don't know why it doesn't show surface granulation).

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I agree that Lunt kit is extremely expensive in the UK and you can’t buy direct from them if there is a reseller in your region - as far as I know. Worth noting though that if you have Lunt kit already and want to upgrade then Lunt do offer a ‘trade up’ program. You won’t get as much for your old kit as selling privately but being able to buy direct from the US makes up for that despite a weak Pound, VAT, Duty and high shipping costs. Shows just how expensive the kit is in the UK. Lunt are good to deal with and the ‘trade up’ program worked out for me. 

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44 minutes ago, Nigella Bryant said:

A good second hand Lunt is ideal. My double stack 60Ds was £1900. 

I looked at your astro solar images and decided that there really was (for me) no need to go up to an 80DS. It will of course take quite some considerable time to reach the same level of imaging proficiency, too! £1900 is a good price S/H for 60DS  compared to UK new prices. The problem in the UK is how the dealers get their supply. Bresser.de import to Europe and Bresser UK supply the dealers like FLO. So they have no option but to charge extortionate prices. FLO (and others) are not the problem here. The price hike compared to buying and shipping to the UK, paying VAT and Duty is a whopping 60% uplift. At those prices, I think it kills the market in the UK for Lunt products stone dead, IMHO. They are (for me) arguably the best product of their type.

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2 hours ago, Nigella Bryant said:

A good second hand Lunt is ideal. My double stack 60Ds was £1900. 

That was a great telescope at an incredible price Nigella. I agree if you can find a good secondhand LS60 and check the performance before buying, it’s a perfect and relatively affordable route into solar Ha. Though I suspect you’d be lucky to find a good DS example under £3k today.  
But for people buying new, to give some idea of how prices have changed, until early last year it was still possible to buy new tilt tuned LS60s for around £1,700 in Europe. The current new price for a single stack LS60MT (B1200, cheap GSO Crayford focuser) is £3,300 in the UK. Same etalon, twice the price. Unless you really need a small ED refractor for night viewing as part of the package - it’s really worth looking at alternatives.
Solarscope 50mm or 60mm perhaps, or one of the new Baader Sundancer filters, which uses a Solar Spectrum etalon - look forward to seeing how these perform. For me, Lunt is no longer the default option for solar, unless you live in the States. 

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Maybe you should consider the Buil Sol'Ex 3D printed digital Spectroheliograph as a cost effective (and more versatile) solution.

http://www.astrosurf.com/solex/sol-ex-presentation-en.html

I went for a DIY "MiniSHG" alternative which is performing very (very!) well.

Valerie's INTI processing software will complete the images in a matter of seconds!!!!

093638_protus.jpg

Ha_stack02.jpg

Mini_SHG.pdf

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12 hours ago, Highburymark said:

New Baader Sundancer filters, which uses a Solar Spectrum etalon - look forward to seeing how these perform.

I read the manual with interest. Typical of BP there is lots of detail and the company is always responsive to questions. From the operating procedure and description, it looks a lot similar to a Quark Chromoshere, e.g. an etalon with mica separation plates and a source of heating to vary the separation of the plates. The heat up time and adjustment time is quoted as 3-5 minutes. When I tried a Quark, it was around 8 minutes to setup and about the same to shift one band. One difference is that the BP requires the temperature offset to be set rather than having presets, so greater  control with some added complexity. The operating principle also requires a tele centric Barlow and operation at around F/30. There are stipulations on the DERF or filter required depending upon the scope and some caveats like not connecting the supply wrong or using the control to exceed the preset by too much e.g. 10 C - why not limit the operation on the controller? BP products, whilst never cheap, are usually well thought through. Some competition in the market place is also a good thing, too. 

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I agree SimM. It’s all about the quality and consistency of the etalon with the Sundancer. If they get that right then I’m sure a lot of people will be prepared to spend the extra money over a Quark. Glad to hear you’re pleased with your new Lunt.

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