21 replies to this topic

[wd8sbb]

Long story, but we now have a Lunt LS60T Ha with a B1200 diagonal.  I had it out the other day (first light for me).  The skys were not real good (smoke/haze), but good enough.  I was sad that the sun seems so dead.  On a whim I got out our Coronado PST (yes an old, prior to Meade involvement) and then was dumbfounded as to why a Lunt was so dim with only some sun spots and no proms..  The PST showed an amazing view of spots with edges, very slight surface texture, proms, bright spots in the sun spot cluster.  I did try the small "tuning" knob in the center of the scope with no real improvement.

 

We view often, but not that long at any one sitting.  I will say that we are not big "adjuster" with the PST.  We have it set in the "sweet spot" and even primarily use sliding of the eyepiece for focus.  Ya, the PST is definitely a starter scope, but does a nice job.  However the thinking was that the Lunt would be an upgrade, and it is nothing of the sorts (as of yet).

 

So, since the Lunt is absolutely new to us, can anyone help us understand why a very reputable scope might be so very sad in it's viewing?

 

TIA

[JRG2]

Does "new to us" mean you bought it used? If so, then check the B1200 filters and don't be too alarmed if the blue filter looks like it has mold growing on it. It is a known problem and an easy fix. Lunt will help you if this is the case.

Edited by JRG2, 18 June 2025 - 08:06 PM.

[bigdob24]

I would check the blocking filter and make sure it’s clear. A new BG38 filter is a cheap fix if needed.

Also could be a tuning problem. Pull up the GONG image before going out and tune the scope to match the view on GONG.

Look for some of the small faint features in the GONG image and tune your scope to show these small and faint features.

The Jacquinot Spot “sweet spot” is the area in the FOV that should contain the whole disk of the sun and show excellent detail across the disk. As you move out of the sweet spot the features will fade out of view. Learn where this area is and keep the disk in that area.

In my scope the sweet spot is in the lower right quadrant 

Dan

[rajilina]

The Jacquinot Spot “sweet spot” is the area in the FOV that should contain the whole disk of the sun and show excellent detail across the disk. As you move out of the sweet spot the features will fade out of view. Learn where this area is and keep the disk in that area.

In my scope the sweet spot is in the lower right quadrant 

Second this. My sweet spot happens to be pretty much in the center (lucky me), but if it moves too far out of that position I lose most detail. It's kind of interesting to move the scope to recenter it, and watch the disk come into tune as it hits the sweet spot again. Night and day difference in visible features.

Edited by rajilina, 18 June 2025 - 08:29 PM.

[rigel123]

When you mention a tuning knob I’m guessing this is an older, tilt tuned dedicated Lunt scope.  As others have mentioned check the filters in the blocking filter, and if they look fine then you might not be turning that wheel far enough to bring the scope on band.

 

I see you are in SW Ohio too.  I sent you a PM.

Edited by rigel123, 19 June 2025 - 05:54 AM.

[TOMDEY]

Agreeing with the above comments --- your description sounds like you were not on band and maybe that little blue filter to replace ($10). The 60mm Lunt should perform nicely. I had one long ago and got a lot of good use out of it. Here's a single frame snapshot of a Venus Transit from my ancient archives. I use Lunt 80/80's now.    Tom

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[Don W]

The B1200 is meant to be used while imaging. The standard blocking filter for that unit is the B600.

 

use the little wheel to tune the unit on band.

[BYoesle]

So it sounds like the scope is indeed used since it has a tilt-tuned internal etalon, and might even be from the era when Lunt was using an ITF instead of the BG38 (like the Coroado BF's). If this is the case, and if it has has deteriorated ("rusted"), it could be replaced with another ITF from Maier, or even better is the ITF Replacement filter from BelOptik. You'll need to check the filter size to make sure it will fit as needed.

[wd8sbb]

I woke up this morning with, why not look at exposed filter surfaces.  Found an issue and then turned on the PC and read the tremendous responses.   Thank you, everyone.  

 

The first filter in the B1200 (coming from the objective) looks terrible.

 

 

Note: I have the filter out of the assembly now.  It seems to be a medium blue clear filter, with nasty stuff on both surfaces.  Otherwise, everything else looks good visually.

 

To answer some questions:

Used. Yes it was my best bud's who is now in alternate stardust form.  

Vintage of scope. Yes, Lunt dedicated solar scope.

 

My new questions:

-Don W said B1200 is for imaging, B600 for viewing. Can someone explain why that is?  FOV?

-BYoesle said could be BG38 or ITF filter.  Other than contacting Lunt, is there a way to tell?

-Is the (blocking?) filter replacement a DIY job?  Seems like it (note above). 

-I remember the rust situation with the PST. We thankfully never had it. I think I remember it being a manufacturing shortcoming. That said, is there some way to avoid this type of deterioration?

  

 

 

   

[rigel123]

Yes, that is the blue filter and as Bob notes there are several replacements available and it is pretty straightforward and inexpensive to replace.  I would simply keep the BF1200 and replace that piece.  The BF1200 is the blocking filter on my 60mm Lunt tilt tuned scope.  I have kept a dessicant pack inside the case and the scope inside unless I am using it and have had no issues with any degradation of the filters since I bought it in 2012.

 

Edited by rigel123, 19 June 2025 - 08:17 AM.

[gstrumol]

Don W said B1200 is for imaging, B600 for viewing. Can someone explain why that is?  FOV?

 

Exactly. For visual the FOV with the 600 is more than adequate to see the full disk (I have a PST with a 5mm BF - 500 - and the full disk easily fits inside the FOV). The 1200 gives you more FOV which gives you more options for imaging.

[BYoesle]

It is a DIY job. You just have to remove any silicone that was applied to hold the filter retaining ring in place. Use a toothpick or hard plastic scrapper, etc. 

 

Beside imaging, larger BF also gives you a better option for binoviewing, which you absolutely should consider.

 

The best improvement you can accomplish would be to double-stack the telescope with a front etalon. Be sure to purchase directly from Lunt and specify your altitude.

 

Double stacking will dramatically improve the contrast performance, but will decrease the filter system transmission, and the best replacement for deteriorated BG38 filter would be the BelOptik UV/IR block on KG3 when they are back in stock in August.

 

Until then, just get a replacement BG38 from Lunt. 

[Don W]

A new B600 2” diagonal is $427

 

A new B1200 2” diagonal is $773

[wd8sbb]

Warren,

Interesting you should mention a desiccant pack inside the case.  We have always had a large one inside our PST case.

 

And again thanks to the great group of folks here on CN.  We were very Astronomy driven years back. We don't get out that much any more, a lot because of nightlights.  The 16" is gone.  We do still have the 8" LX200 "classic" and a 10" project scope when I get to it.  We have however continued solar observation and do that frequently even during that last number of years of "nothingness".  It is really easy to come home and set up the PST and view the sun for 5-30 minutes.   Hope to make similar arrangements for the Lunt but will definitely need a heavier tripod.

 

Ron

[rigel123]

Warren,

Interesting you should mention a desiccant pack inside the case.  We have always had a large one inside our PST case.

 

And again thanks to the great group of folks here on CN.  We were very Astronomy driven years back. We don't get out that much any more, a lot because of nightlights.  The 16" is gone.  We do still have the 8" LX200 "classic" and a 10" project scope when I get to it.  We have however continued solar observation and do that frequently even during that last number of years of "nothingness".  It is really easy to come home and set up the PST and view the sun for 5-30 minutes.   Hope to make similar arrangements for the Lunt but will definitely need a heavier tripod.

 

Ron

I have cleaned house of most of my DSO imaging gear and am pretty much all solar now other than some fun with the Seestar at times.  I have desiccant packs in all of my cases with scopes and cameras etc.

 

As for a mount for the Lunt, the SolarQuest is great.  I use an iOptron CEM25P when I’m imaging animations but use the SolarQuest for quick viewing/imaging when conditions aren’t great for capturing animations.

[vincentv]

A new B600 2” diagonal is $427

 

A new B1200 2” diagonal is $773

The OP does not need a new blocking filters. Lunt sells spares and they're easy to install.

[Don W]

Thanks, just thought it was good info.

[emag]

Glad you got it all sorted out. It can be a quite a shock when the blue filter fails, I know it was for me. It's going to be like new when you replace that. I -highly- recommend the Sky-Watcher SolarQuest mount, it certainly pairs well with my LS60THa. I image with an ASI290MM camera. Rather than take a laptop out in the hot Florida sun, I more frequently use it with Astro Capture on my Samsung Note20. You can find more info re: Astro Capture in the 'Vendor and Group Announcements' forum (I hope I don't sound like I'm shilling, just really enjoy using Astro Capture, along with the SolarQuest mount it allows me to run out between thunderstorms and quickly capture some images like this one).

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[wd8sbb]

Quick update.  I called Lunt, and they were very helpful.  Told me it was a tilt (vs pressure) etalon, mfg 2014, etc. They explained to me the change out saying it was easy but that if I wanted they had repair facility.  I have the "blue filter" on order and should be here in a few days.  I will report back on the results.  Again a BIG thanks to all the folks who replied.

[wd8sbb]

Well I am sorry to report that the blocking filter did not fix the issue.  I installed the filter and took the scope out and it was maybe a bit better, but still lacked brightness and sharpness.  No observable proms today in the Lunt, but several amazing ones are there as seen in the PST.

 

I called Lunt and the person I spoke with apologized saying he was new and ask me to send an email, which I will do here shortly.

 

in the mean time does anyone here know: 

Does the blocking filter need to go in a specific side toward the objective?

 

Any other thoughts on what is causing the issue?

 

I had a PM from another solar observer to connect up and compare since he has a similar Lunt.  That will likely to be my next move.  I am tied up for the next few weeks and not in a huge rush either.  We have the PST which does a really nice job for us.  But would really like to see how the Lunt compares when up to power.     

[bigdob24]

“Does the blocking filter need to go in a specific side toward the objective”
 

Yes it does, the side with the BG38 Blue Blocking filter goes in the scope. The other end will look red when you look into it.

You can slide the BF in or out help with the focus of the eyepieces you use, I have mine marked with tape and when I slid it into that point my low power and high power eyepieces all come to focus.

Too bad you don’t have someone with another BF to try and see if there’s more going on with yours

Dan

[wd8sbb]

Sorry for my poor choice in wording above.  I meant to be asking about the sides of the "blue filter" that I got from Lunt.  Both sides visually look the same.  

 

WRT the B1200 blocking filter as assembled.  I do have the "blue filter" toward the objective, and the "red filter" toward the eyepiece.  But no joy. 

 

It does focus somewhat easy to see against the sun spots, and moving the etalon adjust make a difference, but you have to really "stretch" to see.  Reminds me of a department store plastic optic telescope.  Object is there, but nothing is crisp and clear.