Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

BF size of the PST 40 ?

  • Please log in to reply
4 replies to this topic

#1 paulsky

paulsky

    Apollo

  • -----
  • topic starter
  • Posts: 1,320
  • Joined: 17 Feb 2004

Posted 24 February 2020 - 09:26 AM

Hi,
Can someone please tell me the size of the blocking filter (BF) of the Coronado PST 40 telescope?
Thanks
Paul



#2 AposkiiLola

AposkiiLola

    Sputnik

  • -----
  • Posts: 29
  • Joined: 22 Feb 2020

Posted 24 February 2020 - 10:43 AM

The blocking filter size is 5mm, and is permanently cemented inside the base of a proprietary 1.25" eyepiece holding cell. 

 

You can upgrade this proprietary 1.25" holding cell to the coronado 10mm blocking filter, but this will cost you the price of the 10mm blocking filter from an authorized vendor.


  • paulsky likes this

#3 paulsky

paulsky

    Apollo

  • -----
  • topic starter
  • Posts: 1,320
  • Joined: 17 Feb 2004

Posted 25 February 2020 - 08:50 AM

Thank you very much for your reply.

And the size of the Lunt 35, you know?

Thanks again.

Paul



#4 AposkiiLola

AposkiiLola

    Sputnik

  • -----
  • Posts: 29
  • Joined: 22 Feb 2020

Posted 25 February 2020 - 09:39 AM

The external filter threads on the LS35 etalon are 62mm,   The usable etalon aperture is 35mm.   (the ls35 is discontinued and no longer manufactured, but it was an extremely well made etalon and quite frankly the best lunt product i have ever owned.)

 

The blocking filter supplied with the LS35 was a 4mm,    but you had the option to purchase it with a 6mm.       You can purchase and use all size Lunt blocking filter with any lunt etalon systems,   and the blocking filter size determines the "usable focal ratio to contain a full disc" .    however, bigger blocking filters make the visual experience more comfortable because you will sometimes have to strain your eye looking through smaller ones.   I liken the analogy of using a drinking straw over your eyepiece.  Thats what it feels like on a 4 and 6mm.

 

4mm blocking filter will supply a full disc at 400mm,  

 

6mm @ 600mm

 

12mm @ 1200mm

 

18mm @ 1800mm

 

and 34mm @ 3400mm.  


  • paulsky likes this

#5 paulsky

paulsky

    Apollo

  • -----
  • topic starter
  • Posts: 1,320
  • Joined: 17 Feb 2004

Posted 25 February 2020 - 09:45 AM

Very thanks again!!

Paul




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics