8 replies to this topic

[Clark@Night]

Hi,

Background story:  I had posted earlier about purchasing a COMA helical focuser from Lolli Adriano to replace the stock helical focuser on my LUNT 40 Ha solar scope. 

 

COMA Focuser "made for Lunt 40mm" Problem - Solar Observing and Imaging - Cloudy Nights

 

I hoped that this new helical focuser would have more in-focus and would be more physically robust to support using a binoviewer without sagging.  The initial unit I received earlier this year (2025) was sold to “fit the LUNT 40” but had M52x0.75 threading that did not match my LUNT’s M52x1.0 on the OTA.  I notified Lolli Adriano about the mismatched threading.  Apparently, an earlier customer from Germany had insisted the finer M52x0.75 thread was needed for their LUNT 40.  This was strange since LUNT communicated to me that they have only used the M52x1.0 thread on the OTA for attaching the focuser.  In the end, Lolli Adriano now has available the COMA helical focuser for the LUNT40 in both the M52x0.75 and M52x1.0 versions.

 

First Impressions and Installation:  I received the new COMA helical focuser with the M52x1.0 threads.  The range for the stock helical focuser from the OTA to the blocking filter was ~55-65mm.  The COMA unit was ~52-78mm.  On first approximation, there would be at least 3mm more in-focus which would be a great help for using more powerful eyepieces with my binoviewer.  In actuality, the new COMA focuser mated very nicely with the OTA so I think I may have gained ~4-5mm.  Also note that the COMA focuser has a wider diameter which may contribute to making it easier to rotate.  There are also three thumb screws to hold the blocking filter instead of the single thumb screw on the original focuser.  Here are some photos to show the differences.

 

 

The COMA focuser rotates much more easily than the stock unit.  I cannot say that the rotation is “silky smooth”.  The action has a faint metal-on-metal feeling/faint sound.  I tried wiping out the oily lubricant from the inside of the extended unit and then added some Super Lube.  This helped but did not eliminate the observation.  I’m guessing that the machining tolerances are just very close and this will not be a negative issue.  Maybe all helical focusers have a little bit of this type of action?

Lastly, I threaded the new COMA focuser into the OTA using No. 567 LOCTITE thread sealer as others had recommended elsewhere on the Cloudy Nights forums.  Just to be safe, I let the OTA with the focuser stay open (didn’t add the blocking filter) for a few days to air-out any fumes.

 

 

In my next post, I’ll provide my in-use assessment of the COMA helical focuser on my LUNT 40 Ha solar scope.  Preview was that is works very well!

 

Blue and sunny skies,
Clark in Madison, AL

Edited by Clark@Night, 26 March 2025 - 12:43 PM.

[SCTUSER]

Hi,

Background story:  I had posted earlier about purchasing a COMA helical focuser from Lolli Adriano to replace the stock helical focuser on my LUNT 40 Ha solar scope. 

 

COMA Focuser "made for Lunt 40mm" Problem - Solar Observing and Imaging - Cloudy Nights

 

I hoped that this new helical focuser would have more in-focus and would be more physically robust to support using a binoviewer without sagging.  The initial unit I received earlier this year (2025) was sold to “fit the LUNT 40” but had M52x0.75 threading that did not match my LUNT’s M52x1.0 on the OTA.  I notified Lolli Adriano about the mismatched threading.  Apparently, an earlier customer from Germany had insisted the finer M52x0.75 thread was needed for their LUNT 40.  This was strange since LUNT communicated to me that they have only used the M52x1.0 thread on the OTA for attaching the focuser.  In the end, Lolli Adriano now has available the COMA helical focuser for the LUNT40 in both the M52x0.75 and M52x1.0 versions.

 

First Impressions and Installation:  I received the new COMA helical focuser with the M52x1.0 threads.  The range for the stock helical focuser from the OTA to the blocking filter was ~55-65mm.  The COMA unit was ~52-78mm.  On first approximation, there would be at least 3mm more in-focus which would be a great help for using more powerful eyepieces with my binoviewer.  In actuality, the new COMA focuser mated very nicely with the OTA so I think I may have gained ~4-5mm.  Also note that the COMA focuser has a wider diameter which may contribute to making it easier to rotate.  There are also three thumb screws to hold the blocking filter instead of the single thumb screw on the original focuser.  Here are some photos to show the differences.

 

Stock vs COMA Side Short.jpg

Stock vs COMA Side Long.jpg

Stock vs COMA End On.jpg

 

The COMA focuser rotates much more easily than the stock unit.  I cannot say that the rotation is “silky smooth”.  The action has a faint metal-on-metal feeling/faint sound.  I tried wiping out the oily lubricant from the inside of the extended unit and then added some Super Lube.  This helped but did not eliminate the observation.  I’m guessing that the machining tolerances are just very close and this will not be a negative issue.  Maybe all helical focusers have a little bit of this type of action?

Lastly, I threaded the new COMA focuser into the OTA using No. 567 LOCTITE thread sealer as others had recommended elsewhere on the Cloudy Nights forums.  Just to be safe, I let the OTA with the focuser stay open (didn’t add the blocking filter) for a few days to air-out any fumes.

 

 

In my next post, I’ll provide my in-use assessment of the COMA helical focuser on my LUNT 40 Ha solar scope.  Preview was that is works very well!

 

Blue and sunny skies,
Clark in Madison, AL

Hi.

Following this closely, thanks for the detailed review. I do wish I had got the Feathertouch

but just wasn't sure. My stock helical does Ok, but it seems with Solar getting it "just right" in focus
is not easy. I'm new to Ha so I'm learning.
I have Lunt 40, № #1579

Thanks again :-)

Allan

[Clark@Night]

Hi,

 

Just a quick note to say I accidently included the word "problem" in the topic name.  I asked the moderator to remove it since this isn't a problem anymore!  Sorry about that.

 

-Clark

[Clark@Night]

Hi,

 

I tested the new COMA helical focuser on my LUNT 40mm Ha SS with the 600 blocking filter.  This solar scope is rigged with a DIY bracket on the blocking filter unit that rides along two sealed bearing wheels to help support using a binoviewer.  The earlier stock helical focuser suffered from the notorious “LUNT Wobble” under the additional weight.  I posted about this “Lunt Wobble Workaround” earlier.  I feared that even the more physically robust COMA helical focuser would be challenged over time as well, so kept this support mechanism in place although it seemed solid without being used.  Better safe than sorry, and the dual wheels do provide nice protection from the blocking filter accidently rotating off the optical axis and giving the eyepieces an unscheduled gravity test!

 

The COMA helical focuser remains easy to rotate.  I added a Focus brand rubber gear ring (56-58mm, gear module 0.8) onto the COMA focuser that mates to a large DSLR focusing knob.  (I’m also making an electronic focuser that uses this same gearing for future photography with a PlayerOne Neptune M camera…more on that later.)

 

In-focus range was wonderful!  I usually use Orion Sirius Plossl 25mm eyepieces with an Arcturus brand binoviewer with the barlow section from an Orion Shorty 2x barlow.  With the stock helical focuser, I was unable to bring Orion Sirius Plossl 17mm eyepieces into focus.  The new COMA helical focuser easily brought the 17mm into focus with nice details.  I also pushed the magnification with a set of Celestron 9mm X-Cell LX for fun and it worked.  Not sure if that was practical, but it gives me room to test out a lot of other eyepieces!

 

Overall, I’m very satisfied and would recommend newer COMA helical focuser to anyone wanting to move away from the stock helical focuser.  Below are some photos from the test session.

 

 

Blue and sunny skies to all,
Clark in Madison, AL

[Clark@Night]

Hi.

Following this closely, thanks for the detailed review. I do wish I had got the Feathertouch

but just wasn't sure. My stock helical does Ok, but it seems with Solar getting it "just right" in focus
is not easy. I'm new to Ha so I'm learning.
I have Lunt 40, № #1579

Thanks again :-)

Allan

Hi Allan,

 

I was tempted by the Feathertouch but the cost seemed too high.  I didn't fully appreciate the in-focus and weight support issues the stock helical focuser had at the time.  I must say I'm happy now with the COMA replacement and it fits my mechanical plans for both visual and photography use.  The quality of the LUNT 40mm is exceptional, except for the stock focuser.  I think I may have won the Etalon lottery, too, since my views are fantastic!  Some experience club members have also been surprised by what this small Ha scope can do.  Tempting to try a double stack sometime in the future, but there's no rush!

 

Cheers,

Clark

[SCTUSER]

Hi Allan,

 

I was tempted by the Feathertouch but the cost seemed too high.  I didn't fully appreciate the in-focus and weight support issues the stock helical focuser had at the time.  I must say I'm happy now with the COMA replacement and it fits my mechanical plans for both visual and photography use.  The quality of the LUNT 40mm is exceptional, except for the stock focuser.  I think I may have won the Etalon lottery, too, since my views are fantastic!  Some experience club members have also been surprised by what this small Ha scope can do.  Tempting to try a double stack sometime in the future, but there's no rush!

 

Cheers,

Clark

Hi.

Yeah, for a 1 1/4 focuser the Feathertouch is a lot.

Question, what is shipping like ? (to USA) I'm in no hurry to get it but it sounds very much like a worthwhile upgrade.
My helical is very tight on the tube, so getting it warm first will be the way to go.

I ordered my 40 in Nov 2024 and just got it. So far am loving it, it's truly a plug n play, no hassles !

Allan

[Clark@Night]

Hi.

Yeah, for a 1 1/4 focuser the Feathertouch is a lot.

Question, what is shipping like ? (to USA) I'm in no hurry to get it but it sounds very much like a worthwhile upgrade.
My helical is very tight on the tube, so getting it warm first will be the way to go.

I ordered my 40 in Nov 2024 and just got it. So far am loving it, it's truly a plug n play, no hassles !

Allan

Hi Allan,

 

Shipping of the COMA helical focuser from Italy to the US takes about 4-5 weeks.

 

Have you tried binoviewers with your LUNT 40?  The difference from going mono to bino is really incredible!  You can look up discussions, but basically your brain in processing two signals to provide much more contrast.  Adding a binoviewer would be high on my list for an upgrade before going to a DS system. 

 

The stock helical focuser doesn't do well with the extra weight, nor does it let you use more powerful eyepieces because of in-focus issues.  It still works albeit poorly.  Just be aware.  The contraption I make with the rolling support under the blocking filter was a good workaround and as mentioned, I'm still going to use it with the COMA helical focuser replacement.

 

There are also threads discussing different binoviewers you can review.  I've found the less expensive Celestron clones from China to be just fine as long as you can obtain a nosepiece section that can screw in a barlow lens.  The Arcturus brand binoviewer has most of the necessary parts plus a set of 30mm eyepieces for ~$200.  I added the barlow section from an Orion Shorty 2x barlow, but there are also some inexpensive short barlows on Amazon that can work as well that have detachable lens sections.

 

I'm new to solar viewing as well.  I still have a learning curve in front of me for solar photography!

 

Cheers,

Clark 

[SCTUSER]

Hi Allan,

 

Shipping of the COMA helical focuser from Italy to the US takes about 4-5 weeks.

 

Have you tried binoviewers with your LUNT 40?  The difference from going mono to bino is really incredible!  You can look up discussions, but basically your brain in processing two signals to provide much more contrast.  Adding a binoviewer would be high on my list for an upgrade before going to a DS system. 

 

The stock helical focuser doesn't do well with the extra weight, nor does it let you use more powerful eyepieces because of in-focus issues.  It still works albeit poorly.  Just be aware.  The contraption I make with the rolling support under the blocking filter was a good workaround and as mentioned, I'm still going to use it with the COMA helical focuser replacement.

 

There are also threads discussing different binoviewers you can review.  I've found the less expensive Celestron clones from China to be just fine as long as you can obtain a nosepiece section that can screw in a barlow lens.  The Arcturus brand binoviewer has most of the necessary parts plus a set of 30mm eyepieces for ~$200.  I added the barlow section from an Orion Shorty 2x barlow, but there are also some inexpensive short barlows on Amazon that can work as well that have detachable lens sections.

 

I'm new to solar viewing as well.  I still have a learning curve in front of me for solar photography!

 

Cheers,

Clark 

Hi

Ok, I just ordered the focuser. Not a bad price considering the cost of a FeatherTouch and where it is coming from !

Thanks for the great review, I can't wait. I'll be using some heavy eyepieces, no binoviewer soon ;-)
Also can't wait to put it on my ED 127 and AVX mount.

Thanks Again
Allan

[SCTUSER]

Hi Allan,

 

Shipping of the COMA helical focuser from Italy to the US takes about 4-5 weeks.

 

Have you tried binoviewers with your LUNT 40?  The difference from going mono to bino is really incredible!  You can look up discussions, but basically your brain in processing two signals to provide much more contrast.  Adding a binoviewer would be high on my list for an upgrade before going to a DS system. 

 

The stock helical focuser doesn't do well with the extra weight, nor does it let you use more powerful eyepieces because of in-focus issues.  It still works albeit poorly.  Just be aware.  The contraption I make with the rolling support under the blocking filter was a good workaround and as mentioned, I'm still going to use it with the COMA helical focuser replacement.

 

There are also threads discussing different binoviewers you can review.  I've found the less expensive Celestron clones from China to be just fine as long as you can obtain a nosepiece section that can screw in a barlow lens.  The Arcturus brand binoviewer has most of the necessary parts plus a set of 30mm eyepieces for ~$200.  I added the barlow section from an Orion Shorty 2x barlow, but there are also some inexpensive short barlows on Amazon that can work as well that have detachable lens sections.

 

I'm new to solar viewing as well.  I still have a learning curve in front of me for solar photography!

 

Cheers,

Clark 

Hi again.

I just got my COMA focuser. Turns out my local PO held it up for some reason, but I got it.
It came well lubricated in what appears to be a green synthetic lithium grease and a lot of it. After a number of wash and clean with first brake cleaner and then 91% IPA I did get 99% of the grease out of it. Just a tiny bit remaining it seems. I let it sit in the hot Sun too dry for a day and  no smell left at all.
Left it and my Lunt 40 sit in the hot Sun this morning and it took all of 60 seconds to remove the Lunt focuser and install the COMA. Looks like they used a small amount green Locktite on the threads. Focuser came off easily. The COMA went on just as fast. A little rough feeling focusing but a 90% improvement over the Lunt helical focuser. I will remove the COMA and lube it with grease I got for my Questar.

I'm very happy

Allan

EDIT;

Thanks for the GREAT review and pictures. You sold me on it and I'm just soo happy I got it, Thank You !

Edited by SCTUSER, 02 June 2025 - 12:02 PM.