Lunt LS50THa and Nagler 3 - 6mm Zoom

[MalcolmM]

Hi,

Does anyone use this combination (Lunt LS50THa & 3-6mm Nagler Zoom)?

I find I have to rack the focuser all the way in to get focus. I feel I am probably not at 'perfect' focus because I cannot rack the focuser in any further to obviously defocus. i.e. I can only defocus on one side of the 'in focus' point.

I hope this explanation makes sense! Has anyone else found the same issue?

 

I also find I have to have the pressure tuner wound pretty well fully in to get the surface detail and proms. Is this normal? I have seen elsewhere on this forum that some people have to wind the pressure tuner pretty well fully in.

 

I should caveat the above by saying I have only used this scope a couple of times and it took me 3 sessions before seeing the proms and surface detail. But when it all comes right the views are fascinating! I can get good focus and fantastic views with a Type 5 Nagler 16mm, but this obviously gives quite low magnification.

Many Thanks,

Malcolm

[Highburymark]

Many Lunt scopes only come on band at the end of the pressure tuner travel. Both my LS50 and LS60 were the same. If you’re getting good results nearly at the end, try going all the way - just to see if you get any more surface detail. You can’t do any damage to the scope. 
Sometimes regreasing the o-rings and the piston can help seal the system and ensure the pressure tuner works properly, but that’s only if you think it might be losing pressure. Yours sounds perfectly normal and good the hear you’re getting decent views. 
The most powerful eyepiece I used with the LS50 was 6.5mm - so I would have thought that the Nagler zoom would be at the limits of the scope’s capability. Plossls and orthos work well if you have any at usable focal lengths. Can’t help with the focus position - I had lots of problems with the helical focuser and eventually replaced it with a Moonlite.

[MalcolmM]

Thanks for the reassuring reply @Highburymark. I do not think the tuner is loosing pressure so it's good to hear that winding it all the way in is fairly common.

I'll simply have to experiment with different eyepieces; lack of clear skies has hampered me so far.

I too don't particularly like the helical focuser but given that it 'does the job' and I have been very extravagant on new kit over lockdown it'll have to do for now

Malcolm