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astro_al

Lunt LS60DS Tuning Question

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I received a new to me Lunt LS60 double stack today. Feeling happy about having the option to view in Ha again.

I managed all of 10 minutes which allowed me to test that I could focus OK with the binoviewers and a 1.7x GPC. Great that you can unscrew the EP holder in the blocking filter diagonal to reveal a T-thread for the bayonet for the binoviewer. Also nice with the new Maxbrights that you can screw the 1.7x GPC into the nose of the binoviewer.

So with focus achieved (maybe 4mm to spare) I screwed in the pressure tuner and could see the view change from a blank disk to something with detail and a few small proms. Next started to adjust the front filter with the wheel but the clouds moved in. Promising start though.

My question to other owners of this scope is do you tune in the scope in single mode first before adding the second filter and then start tuning that? I read online that this is the way to approach it. If so do you do this once and then 'set and forget', or do you leave the front filter in place and tune both each session?

Thanks for any tips.

Al

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That’s the way I always did it when I owned pressure tuned double stacks Al. Single stack first, then tune with the double stack filter. The double stack stayed on the scope from that moment on - never took them off. Continue to experiment tuning the DS filter during each session - you’ll find it helps bring out different solar features, depending on activity that day. It’s a great set up - congratulations!

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Thanks @Highburymark - so once you had the pressure tuner sorted for the internal filter in single stack mode you left it alone from session to session and just tweaked the double stack filter?

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In addition to this is the practice of "clocking", that is rotation of the DS unit relative to the SS unit.  Significant improvement can often be achieved by this method and there is a special adaptor commercially available to assist with this.  Ha viewing is an interesting learning curve!     🙂

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As Peter said above there is and adapter that's available from Telescope Services not designed for this purpose but works well, makes it easy to rotate the front etalon as well as quickly fit and remove it, not cheap but very useful.

Another thing that can catch you out are false Suns, these appear in a circle round the real one and can be confusing if you start trying to tune in on one.

Dave

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9 minutes ago, nicoscy said:

Link to the adapter please?

I'll try and find it, did have it saved but MS helpfully  deleted all my favourites on the last update.

Dave

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41 minutes ago, Peter Drew said:

Ha viewing is an interesting learning curve!     🙂

And I thought this would be simpler than the Quark! 😁

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21 hours ago, astro_al said:

Thanks @Highburymark - so once you had the pressure tuner sorted for the internal filter in single stack mode you left it alone from session to session and just tweaked the double stack filter?

No - what I said was a bit confusing - I played around with the pressure tuner all the time. Just meant I tuned it in single stack first time before adding the second etalon. From then on didn’t take the ds filter off, but used pressure tuner and ds tilt tuner. 

 

3 hours ago, nicoscy said:

Link to the adapter please?

Looks like a nifty bit of kit, though the filters are well machined, and you can easily unscrew them by a single rotation without any danger of them falling off. Just have to be sure you don’t forget about it, and unscrew it by another rotation next time, and the time after that, and the next time, and ........ 

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30 minutes ago, Highburymark said:

No - what I said was a bit confusing - I played around with the pressure tuner all the time. Just meant I tuned it in single stack first time before adding the second etalon. From then on didn’t take the ds filter off, but used pressure tuner and ds tilt tuner. 

Got it. Thanks for the clarification.

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5 hours ago, Peter Drew said:

In addition to this is the practice of "clocking", that is rotation of the DS unit relative to the SS unit.  Significant improvement can often be achieved by this method and there is a special adaptor commercially available to assist with this.  Ha viewing is an interesting learning curve!     🙂

I have heard the term 'factory matched' when describing a second filter purchased with a scope vs adding the second filter later. If the filters are matched does this remove the need for "clocking"?

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Everything is variable in Ha astronomy!   Things change day to day due to temperatures, atmospheric pressure, whether objects on the Sun are approaching or receding, type of feature, just to name a few.  This is part of what makes solar viewing so interesting.  And then there's solar imaging!   🙂

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7 hours ago, Peter Drew said:

In addition to this is the practice of "clocking",

So, not making a 10-year old Lunt appear to be only 2 years old, then? 

🙂

 

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Managed a few sessions today between the clouds. Used the scope in both single and double stack mode and have got to grips with the tuning. Pleased with the results but I did think I would be able to get a little higher magnification, particularly in single stack mode.

So far I am using about 30x in double stack and about 40x in single stack otherwise the view starts to soften. Typically I am sticking with 30x in both modes. I think 50x on a day with better seeing in single stack mode might be doable.

I did want the Lunt for lower mag, full disk views but it would be nice to have the option for slightly higher magnification to get tighter in on the proms in single stack mode. I am wondering if I get an adapter for the FC-100 if that combination would support a bit more magnification, so single stack but using the front-mounted etalon with a different doublet.

Nice to be viewing in Ha again :) 

Edited by astro_al

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I doubt whether fitting the front etalon to a different, albeit better refractor will make much difference, the aperture will still be 60mm.     🙂

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It will, but I had no problem using the Quark with an 0.8 exit pupil, (95x in a 76mm refractor) so I was hoping for the equivalent sharpness and brightness (seeing permitting) with a 60mm aperture at 75x. I was thinking the FC-100 because the increased focal length would make it easier to get to 75x with the eyepieces I have.

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