Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_dslr_mirrorlesss_winners.thumb.jpg.9deb4a8db27e7485a7bb99d98667c94e.jpg

vineyard

Lunt 50PT Ha o-rings / pressure tuning

Recommended Posts

Hello,

I recently bought a 2nd hand Lunt 50PT Ha (on a different platform).  The vendor said he had only used it a handful of times since buying it and it shipped in the original box.  It seems fine, focuses well (although I find the helical focuser a bit of a pain compared to crayfords).  But it doesn't show any Ha features on the surface of the Sun!

Long story short, I completely opened up the pressure tuner and found a bizarre thing.  Its well greased, there's no detritus (and it doesn't lose pressure).  But there was only one O-ring in it?!  The tuner itself has grooves for two o-rings and the video on Lunt's website (on how to replace o-rings) shows a tuner with two o-rings when it comes out.  And they ship replacements in batches of two.

So I'm guessing that somehow the original scope shipped with only one o-ring fitted? (It wouldn't make sense for the vendor to have removed one?).

I'm hoping that's what it is, b/c then the inability to resolve Ha features may just be insufficient pressure building up?  In which case, does anyone know where I can get these replacement o-rings please (Lunt's US website has them but that's only for shipping to the US)?

If it's not that, and the scope is only meant to have one o-ring, any ideas on the problem?  The ring & tuner seem well greased.

Thank you!

Vin

(EDIT: in the meantime, the next time the sun comes out, I'm going to try moving the current o-ring from the higher groove to the lower groove in case that longer distance from the base is why the pressure isn't building up sufficiently?)

Edited by vineyard

Share this post


Link to post
Share on other sites

Some of these scopes did indeed ship with only on O ring, you can get spares from Bresser either direct or through Telescope House.

info@bresser.de

Dave

Edited by Davey-T
  • Like 1

Share this post


Link to post
Share on other sites

Wow, how did they let that happen; doesn't bode well for product control?  Anyway, thanks Dave - I'd tried looking on their website and it's not listed, but will try calling directly!  (I'll also look in my local hardware store - no doubt it'll be a bespoke thickness just because...)  Cheers, Vin

Share this post


Link to post
Share on other sites

Thanks Davey-T & johninderby.  I eventually contacted Lunt directly, and Bresser Europe in Germany are sending some o-rings :) (FLO also recommended speaking to Bresser).

Btw, while talking to Faye at Lunt she explained that the 50THa ships with 1 o-ring only deliberately.  They found that if there were two o-rings, re-threading the tuner on required too much force.  So it is now deliberate that the first (lower) groove is empty, and the o-ring is in the second (higher) groove.

Anyway, happily after re-greasing, taking the tuner off completely to equalise and then slowly threading back (and, ahem, putting a black t-shirt over my head) I managed to see some Ha features this morning :)

Cheers,

Vin

  • Like 1

Share this post


Link to post
Share on other sites

Glad things are working out for you now Vin.

I found a way to attach a second o-ring to the LS50 and wrote a brief report on SGL about it 2/3 years ago. It involved loosening the end screw on the piston which made it slightly easier to screw it onto the brass housing. But sounds like you don’t need any further tinkering. Enjoy - it’s a great little ‘scope.

Share this post


Link to post
Share on other sites

Glad you saw some detail- just wait til the sun gets more active and it will be truly wonderful!  I luv my double stacked LS50 :)

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By jambouk
      I asked a few weeks ago about charging two batteries from one solar panel. I’ve now got a solar controller which can do this, see below, but I’m confused by the instruction manual, especially how I should set the “charging priority”. I assumed the unit would charge battery 1 until full, then move on and charge battery 2 until full, then go back to 1. I’m not sure what this charging priority is - image of the relevant page from the manual below. I’d be grateful to hear what you think it means.
      Thanks.
      James.


    • By MalVeauX
      Hey all,
      I made an acquisition and processing tutorial a while back (3 years ago? Yikes!) and it is fairly dated in terms of what I'm doing these days. I've been asked for a long time to make a new one showing what I'm doing these days. Specifically how I'm processing a single shot image for both the surface and prominences and how to process them together to show prominences and the surface at once. I've abandoned doing split images and composites and strictly work from one image using layers. Acquisition does not use gamma at all anymore. Nothing terribly fancy, but it's not exactly intuitive so hopefully this new video will illustrate most of the fundamentals to get you started. Instead of an hour, this time it's only 18 minutes. It's real time from start to finish. I'm sorry for the long "waiting periods" where I'm just waiting for the software to finish its routine, it lasts 1.5 minutes and 30 seconds tops typically at first. The first 4 minutes is literally just stacking & alignment in AS!3. I typically will go faster than this, but wanted to slow down enough to try to talk through what I'm doing as I do it. Hopefully you can see each action on the screen. I may have made a few mistakes or said a few incorrect things or terms, forgive me for that, this is not my day job. I really hope it helps folk get more into processing as its not difficult or intimidating when you see a simple process with only a few things that are used. The key is good data to begin with and a good exposure value. Today's data came from a 100mm F10 achromatic refractor and an ASI290MM camera with an HA filter. I used FireCapture to acquire the data with a defocused flat frame. No gamma is used. I target anywhere from 65% to 72% histogram fill. That's it! The processing is fast and simple. I have a few presets that I use, but they are all defaults in Photoshop. A lot of the numbers I use for parameters are based on image scale, so keep that in mind, experiment with your own values. The only preset I use that is not a default is my coloring scheme. I color with levels in Photoshop, and my values are Red: 1.6, Green 0.8, Blue 0.2 (these are mid-point values).
      Processing Tutorial Video (18 minutes):
      https://youtu.be/RJvJEoVS0oU
      RAW (.TIF) files available here to practice on (the same images you will see below as RAW TIFs):
      https://drive.google.com/open?id=1zjeoux7YPZpGjlRGtX6fH7CH2PhB-dzv
      Video for Acquisition, Focus, Flat Calibration and Exposure (20 minutes):
      (Please let me know if any links do not work)
      ++++++++++++++++++++++++++++++++++++++
      ++++++++++++++++++++++++++++++++++++++
      Results from today using this work flow method.
      Colored:




      B&W:




      SSM data (sampled during 1.5~2 arc-second seeing conditions):

      Equipment for today:
      100mm F10 Frac (Omni XLT 120mm F8.3 masked to 4")
      Baader Red CCD-IR Block Filter (ERF)
      PST etalon + BF10mm
      ASI290MM
      SSM (for fun, no automation)


      Very best,
       
    • By BabyPepper
      160mm x 1600mm + Lunt LS50C etalon.
      Thanks for looking!
            <br>    

       
    • By Phillips6549
      We have a fledgling Astronomical Society at my place of work and we're intending to have some telescopes available for colleagues to view the transit of Mercury in November.  While the majority will use appropriate solar filters it would be good to have at least one set up for projection.  However, we only have reflectors and Schmitt or Maksutov Cassegrain scopes among the members.  I was considering buying a small refractor second hand to use for this but thought I'd ask for advice here first.
      Which is the best type of scope to use for projection?
      What do we need to look out for (overheating & fire risks for example)?
      What is the best umbrella to protect kit from the inevitable deluge on the 11th November? ☔
       
      Thanks
      Mark
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.