Composite Shot - LS60 SGL5

[NickH]

So...I had a chance to really give Stephen Green's Lunt LS60T a go at SGL5, and apart from the sweet spot (large) and the etalon tuner (only works in about 4mm of the end of the play/rotation), it held up incredibly well

This image set at F40 using the Lumenera Skynyx 2-1m

Combined in imerge, processed using Registax 4 and CS2. Stack of 4 x 1000 frame AVI files captured with Lucam Recorder

LS60/B1200

HEQ5 Mount

Televue 2.5X Powermate, stacked with a Celestron 2X Barlow

Ironic isn't it that this will probably be used to promote them... :-), the irony being that they refused (they being one individual) to supply me one to review..

[russ]

It's a wonderful image Nick, i could see why they may want to use it. Have you changed your view slightly on the LS60?

[NickH]

I have now seen a good one...a really good one... the etalon tuning was next to a joke, (Stephen in fact taped it up on the position we found...that's how much it matters!), and the sweet spot at prime focus was very large (black band over the disc at times)...BUT...I have said since day one, that the CaK scopes they make are superb, and that there is NO reason at all why, if the QC was done properly, and no interference from astigmatic B600's or misaligned optics, that these could not perform well...on spec they are a 0.75A H-A instrument made by people who have been making such things for a long long time.

However, Stephen now said that this model would retail at £1900 (almost impossible for find a UK price, so based on USD at over $2000, that seems close), which is only a few hundred less than a Solarscope SV50...

At the price Stephen paid for his (quite staggeringly cheap!), it's a belter...

[NickH]

And here's a one shot image...proms and surface, same scope, same setup, just adjusted the Gamma (Hey...what's that??? :-) sorry...in joke)...

[russ]

So it's a good scope showing promise that a few improvements should sort? But too close in price to a SV50 for comfort. Is it ex-Coronado people at Lunt? I can't remember what the story is now behind the company.

[NickH]

It's build quality is pretty good...the OTA tube looks well made, the focuser was good. the etalon was (as Stephen will testify) all over the place...literally no play at all for most of the tuning arc.. The SV50 price now AFAIK is pretty close (like I say, not sure on the LS60T /B1200 price as nobody lists it), and yes, it is Andy Lunt and Rikki plus some others who are the team behind it...

[pauldaviesuk]

The question of the tuner onn the LS35 and LS60 came up on the Lunt forums (unfortunately, I can't find the post atm). Apparently it is a different mechanism from the tuners on the PST or such like.

On those instruments the tuner is designed to sweep the bandpass across the central Ha wavelength, to allow the viewer to tune in doppler shifted light from features traveling radially out from the sun.. but you knew tha already

Howerver, on ther LS35 and LS60, the tuner is designed for a different propose. Apparently it it there to tune the etlalon to the local thermal and atmospheric conditions. For most of us that will equate to the tuner wheel sitting close to the far end of its travel. Once it s been tuned in, it shouldn't (needn't) be touched again during that ovserving session.

It isn't therefore (apparently) appropriate to compare the tuner of the LS35/LS60 to the tuner on the PST, or so I understand.

Regarding the price, I've been quoted between £960 and £1085 for the LS60THa/B600/C and £1650 for the LS60THa/B1200/C. Note - these prices are for vanilla units with the normal 10:1 crayford focusser and without the new 'Pressure Tuner'.

cheers

Paul

[NickH]

Paul

It's loose for 95% of the entire range, not "not tuning for atmospherics", it's literally like you have undone it and it's slopping about... for it only to do anything at all in the last few mm is just odd...not a feature..

And a tilt tuner adjusting for thermals?? erm it's behind an ERF...it should have no real "local thermal" issues...it's an isolated pair of fused silica plates... directly behind a dobbing great big ERF.. (LS35) or down the body (LS60) behind an even larger ERF. I guess, if they have thermal issues (a solid etalon uses these of course), then the air gap would change (heating/expanding etc)...but it should not really happen..

Atmospheric changes , yes, the air pressure changes do make a difference, had a full lecture on that from the man who built the original Coronado's...but that's surely why Lunt introduced the pressure tuning system....this one was a standard one...not a pressure tune model for the record.. I have to tweak the SV50 from day to day or the PST80 to compensate for these air pressue changes that's for sure.

In terms of doppler shifting this one...you had about 2mm if you were lucky to move anything before it went totally off band/gigantic sweet spot, that's unlike any other solar H-A instrument I have tested (and I've used quite a few!)

None of the other makes I have tested have this limited a range, but if that's what they want to say...then who am I to argue :-) they built it... like they built all those wonderful B600's :-) (a few people on here could probably shed light on that story!)

Anyway...one final shot from it, AR at SGL5

[NickH]

I remember that post on the forums too... for the record...

Fact is, this one delivered good views...just scouting through google, and not much else to report on any good images, however I have seen a few on the Lunt forum, not many, but a few..

[pauldaviesuk]

Like I said.. I'm just repeating what I read.. take it or leave it

Paul

[NickH]

Aye....good point...not going to let a scope worry me...

Nice to finally use one that worked well though..