Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1
snorkler
Aperture Aficionado
*****

Reged: 10/11/04

Loc: Bay Area, California
Polishing optical acrylic lens element in a Lunt s new
      #6075701 - 09/11/13 07:05 PM

An optical acrylic lens element in the prism of my Lunt solar scope developed mineral deposits in storage. I removed the prism.



Remove the prism by loosening the set screws. Then unscrew the tube. You can see the fogged element inside.




Remove the retaining ring with a spanner wrench. For lack of better tools in Bryce Canyon National Park, we used needle nose pliers.


Edited by snorkler (09/11/13 07:42 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
snorkler
Aperture Aficionado
*****

Reged: 10/11/04

Loc: Bay Area, California
Re: Polishing optical acrylic lens element in a Lunt s new [Re: snorkler]
      #6075761 - 09/11/13 08:02 PM

Photo shows the removed lens element. Until we removed it, I thought the element was a multi-element lens fogged internally. After removal, I saw a single element, which was coated on both sides with mineral deposits. Washing did not remove the deposits completely.



After searching the WWW for polishing compounds for optical acrylic plastic, I found three recommended compounds: Meguiar's PlastX, Novus plastic clean and shine, and Brasso. We drove 80 miles to the nearest city, Cedar City, because Meguiar's is sold in Walmarts.



I polished the lens element (or filter) with the Meguiar's using cotton underwear. The results were amazing.





Views through my solar scope are as good as they have ever been.

Edited by snorkler (09/11/13 08:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Sean Cunneen
Let Me Think
*****

Reged: 08/01/07

Loc: Blue Island Illinois
Re: Polishing optical acrylic lens element in a Lunt s new [Re: snorkler]
      #6075879 - 09/11/13 09:09 PM

Nice!

Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Polishing optical acrylic lens element in a Lunt s new [Re: Sean Cunneen]
      #6076109 - 09/11/13 11:42 PM

Good work! Many would be rather too trepidatious.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Crayfordjon
Vendor - Zerochromat
*****

Reged: 06/17/09

Loc: UK
Re: Polishing optical acrylic lens element in a Lunt s new [Re: GlennLeDrew]
      #6076271 - 09/12/13 01:57 AM

I once experimemterd making acrylic lenses, I polished them with plasticene laps and rouge, the finish was brilliantly clear.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Footbag
Postmaster
*****

Reged: 04/13/09

Loc: Scranton, PA
Re: Polishing optical acrylic lens element in a Lunt s new [Re: Crayfordjon]
      #6077090 - 09/12/13 02:00 PM

Is this the same issue as the "rusting"? Seems like a very simple solution for a worrisome problem.

Post Extras: Print Post   Remind Me!   Notify Moderator  
richard7Moderator
Not Quite
*****

Reged: 11/02/07

Loc: Sacramento
Re: Polishing optical acrylic lens element in a Lunt s new [Re: Footbag]
      #6077215 - 09/12/13 02:54 PM

This is something that neither I nor Cloudy Nights would recommend. You're dealing with something that could cause permanent eye damage.
If it looks bad, send it back to the manufacturer.


Post Extras: Print Post   Remind Me!   Notify Moderator  
RikkiHocking
Vendor - Lunt Solar Systems
*****

Reged: 02/15/08

Loc: Tucson, AZ
Re: Polishing optical acrylic lens element in a Lunt s new [Re: richard7]
      #6077459 - 09/12/13 05:24 PM

I am sorry to see you are having this issue. We have come across it on a few blocking filters. Sometimes there is a film that develops on this piece of glass. There is no degrading of the filter. There are no coatings on this piece. You can feel free to either clean the glass as you have seen here or contact Lunt Solar and we can send you a new piece.
Thank you,
Rikki Hocking
Lunt Solar Systems
(520)344-7348
r.hocking@luntsolarsystems.com


Post Extras: Print Post   Remind Me!   Notify Moderator  
richard7Moderator
Not Quite
*****

Reged: 11/02/07

Loc: Sacramento
Re: Polishing optical acrylic lens element in a Lunt s new [Re: RikkiHocking]
      #6077908 - 09/12/13 10:44 PM

Thank you Rikki.

Post Extras: Print Post   Remind Me!   Notify Moderator  
snorkler
Aperture Aficionado
*****

Reged: 10/11/04

Loc: Bay Area, California
Re: Polishing optical acrylic lens element in a Lunt s new [Re: richard7]
      #6079129 - 09/13/13 05:45 PM

I hadn't considered the element could have been coated, or glass. I would have backed off if I had seen any optical change, but I agree I should have contacted Lunt before proceeding as I did. You get used to doing your own repairs in park isolation.

Since my problem is fixed, I won't request replacement of the blocking filter. Thanks Rikki and Richard for your feedback.


Post Extras: Print Post   Remind Me!   Notify Moderator  
ion
professor emeritus


Reged: 04/26/08

Loc: Bortle Scale 2
Re: Polishing optical acrylic lens element in a Lunt s new [Re: snorkler]
      #6079185 - 09/13/13 06:20 PM

The Lunt website refers to this phenomenon as "premature failure" of the Induced Transmission Filter (ITF):

http://www.luntsolarsystems.com/technical-manuals.html

How can simply removing the damage or "film" be an acceptable repair? What is this "film" composed of if the part is not coated? Where exactly did all these "mineral deposits" come from and why don't they affect any other internal lenses in the telescope?

http://www.optcorp.com/media/catalog/product/cache/1/image/9df78eab33525d08d6...


Post Extras: Print Post   Remind Me!   Notify Moderator  
RikkiHocking
Vendor - Lunt Solar Systems
*****

Reged: 02/15/08

Loc: Tucson, AZ
Re: Polishing optical acrylic lens element in a Lunt s new [Re: ion]
      #6079227 - 09/13/13 06:54 PM

Hi Ion,
We do not use ITF's in our systems anymore. The poster image you have is very old. This is BG glass. There are no coatings on it. The glass itself is the filter. We have not had any film on any other element.
Thanks,
Rikki Hocking
Lunt Solar Systems


Post Extras: Print Post   Remind Me!   Notify Moderator  
marktownley
Postmaster


Reged: 08/19/08

Loc: West Midlands, UK
Re: Polishing optical acrylic lens element in a Lunt s new [Re: RikkiHocking]
      #6133232 - 10/12/13 02:57 PM

What a revealing thread. Very interesting

Post Extras: Print Post   Remind Me!   Notify Moderator  
BYoesle
Post Laureate
*****

Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Polishing optical acrylic lens element in a Lunt s new [Re: marktownley]
      #6133394 - 10/12/13 04:34 PM

Makes sense with the use of a hot-mirror ERF coating with the front filters or on the collimator lens of an internal etalon scope.

See the BG glass filter curves in this document: http://www.us.schott.com/advanced_optics/english/filter/us/index.html


Post Extras: Print Post   Remind Me!   Notify Moderator  
marktownley
Postmaster


Reged: 08/19/08

Loc: West Midlands, UK
Re: Polishing optical acrylic lens element in a Lunt s new [Re: BYoesle]
      #6133542 - 10/12/13 06:18 PM

Tee hee hee - I was looking at the same webpage Bob

Post Extras: Print Post   Remind Me!   Notify Moderator  
BYoesle
Post Laureate
*****

Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Polishing optical acrylic lens element in a Lunt s [Re: marktownley]
      #6133811 - 10/12/13 08:29 PM



Post Extras: Print Post   Remind Me!   Notify Moderator  
BYoesle
Post Laureate
*****

Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Polishing optical acrylic lens element in a Lunt s new [Re: BYoesle]
      #6147765 - 10/20/13 01:33 AM Attachment (8 downloads)

BG38 looks like a likely candidate for the filter used, with decent transmission @ 656 nm ~ 50% :

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
16 registered and 27 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 982

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics