Username:

Password:

Altair AstroDIO DehumidifiersAtik CamerasModern AstronomyDavid HindsNe3 Filters

Author Topic: PST EP holder adapter  (Read 2755 times)

0 Members and 1 Guest are viewing this topic.

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
PST EP holder adapter
« on: 15:14:26, 21 February, 2011 »
Any of you guys here know of an adapter available, maybe in Europe, that will allow screwing that piece into a 1,25" barrel.
I'd sure like to find something like that to make it easier to use the PST BF on a modded scope I'm putting together.

Offline Merlin66

  • Poster God
  • *****
  • Posts: 1744
  • Designed to Perfection
Re: PST EP holder adapter
« Reply #1 on: 15:26:29, 21 February, 2011 »
A couple of "modders" have managed to graft it onto the outlet of a star diagonal - unscrew the original 1.25" eyepiece holder from the diagonal and using Lilliput putty form a new threaded collar using the PST part.
I have made a 2" adaptor for the PST eyepiece section using an Orion Prime focus adaptor...PM me for details....
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #2 on: 15:58:44, 21 February, 2011 »
I made a nice adapter from an old compression ring 2X1.25" adapter I had that works good and I didn't have to do anything to the PST holder.
For now I'm kind of wanting to leave that PST part alone in case I want to put a PST back together again with the house.

I ended up getting a Denk/Spectrum 60mm conversion for the standard PST.
It has a superb objective, but they missed some measurements on their OTA I think.
Anyway, there is no way to get close to focus, with my DMK anyway, without running the penta-prism into the top of the house.
Visual use is amazing so I figured there was some potential there.
They also supplied a 10mm BF in the same type of mount as the 5mm.

I decided to ditch the whole house to get that miserable prism out of the optical train.
Here in the states I can get the adapters needed based on the 2" standard SCT threads to put things together and use an SCT focuser.
The weather is just terrible, but the short test run I did showed me this thing is going to work great.
I can probably stay with using a 2X1.25 adapter, but wondered if there was a simple way to keep things at 1.25"

I've done this a little different than what I've seen most of you guys do with this type of mod, in that I've left the Etalon cell attached to the Denk supplied OTA and added adapters, focuser, spacers, etc behind it to get the correct distance

Offline Nomis Elfactem

  • Administrator
  • Galactic Poster
  • *****
  • Posts: 12932
    • The View From A Room
Re: PST EP holder adapter
« Reply #3 on: 17:17:35, 21 February, 2011 »
John - on my mod I've just sorted out attaching my PST BF5/EP holder to a Borg Helical focuser using a T'ring spacer that then screws to the focuser and locks the BF in place against the flaired flange on the PST EP holder.  When I get a mo I'll post some images.

I've been waiting weeks to get to test it but the sun just ain't playing ball in the UK at the moment....

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #4 on: 17:38:51, 21 February, 2011 »
I'd like to see how that one works Simon.
Seems like someone here had an adapter from Baader?, maybe, that clamped to the flange of the NF housing too.

Offline Merlin66

  • Poster God
  • *****
  • Posts: 1744
  • Designed to Perfection
Re: PST EP holder adapter
« Reply #5 on: 18:39:05, 21 February, 2011 »
The distance from the PST etalon to the focus is fixed by the optics at 200mm. This is the position to target for any adaptors etc.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #6 on: 20:15:51, 21 February, 2011 »
I know a lot of people who do the so called stage 2 mod try to fix that 200mm separation with the components. and mounted after the focuser.
Seems to me it works better with the etalon mounted ahead of a focuser, then spacers etc to reach that separation.
Then the focuser also controls that critical distance.
I think if I ever get flush enough to buy an ERF for a larger refractor, I'll try to devise some way to mount the PST etalon assembly so it's at the objective end of the focuser.

Offline Nomis Elfactem

  • Administrator
  • Galactic Poster
  • *****
  • Posts: 12932
    • The View From A Room
Re: PST EP holder adapter
« Reply #7 on: 20:36:20, 21 February, 2011 »
Mine is at the objective end John.  The Borg helical focuser is a great solution. 

The only thing that takes a bit of sorting out is getting the etalon within 200mm of the focal length of the objective without the use of another focuser... it's critical both sides of the etalon sadly.

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #8 on: 20:59:54, 21 February, 2011 »
Somewhere I have a photo of a build a guy did with 2 focusers.
I'll have to find that again and see if there are some measurements given and maybe some information about why 2 were needed.
It seems like if you drew a ray trace and got the etalon in the correct position, it could all be done with one focuser.
I had hoped to get out and do some more testing with my set up, but it was -17°F here this morning and now the wind is up and a ground blizzard blowing.

Offline Merlin66

  • Poster God
  • *****
  • Posts: 1744
  • Designed to Perfection
Re: PST EP holder adapter
« Reply #9 on: 21:29:54, 21 February, 2011 »
If you do the set up correctly you only need the one focuser between the etalon and the final focus.
I have a comprehensive write-up available on Modded PST's which includes many illustrations of alternative solutions. PM me for a copy.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #10 on: 21:38:11, 21 February, 2011 »
I have a very extensive paper with a lot of references by Ken Harrison.
Did you send that to me?
Some kind soul here sent it to me some time ago.
The nice thing about this forum is the extent we can go in discussions about Ha scopes.Only place I know of with so much information available under one roof.

Offline Merlin66

  • Poster God
  • *****
  • Posts: 1744
  • Designed to Perfection
Re: PST EP holder adapter
« Reply #11 on: 06:53:29, 22 February, 2011 »
John,
Yes that's mine....
I'm now working on a double stacked PST etalon concept which looks very promising....
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #12 on: 12:58:32, 22 February, 2011 »
Ah, then thank you again.
Over time I've accumulated a fair amount of data about improving especially the PST Ha.

Offline Nomis Elfactem

  • Administrator
  • Galactic Poster
  • *****
  • Posts: 12932
    • The View From A Room
Re: PST EP holder adapter
« Reply #13 on: 14:24:40, 22 February, 2011 »
Took some photo's of the construction stages for my PST BF5 to helical focuser solution....

I've got 15mm travel in the focuser so will now be able to reach focus no probs once I'd sorted out the T'adapter combination.

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline JohnM

  • Full Member
  • ***
  • Posts: 366
Re: PST EP holder adapter
« Reply #14 on: 14:39:59, 22 February, 2011 »
Thanks Simon,
so, the part with the scale is your helical?
What is the part that has the ring which will clamp down over the flange on the bottom of the EP holder assembly?
Sorry, I still don't quite make out all the parts you used.
Here is a pic of what I did to affix that EP holder to a 2X1.25 adapter.
3 small self tapping screws run into the top of the adapter and hold down the flange.

 

ukbuysellRemote Imaging from AustraliaSharpSkyblank APTUKAI on Facebook
Powered by SMF 2.0.13 | SMF © 2006, Simple Machines LLC
DarkBreak by DzinerStudio. Theme modified by The UKAI Team

Page created in 0.158 seconds with 36 queries.
TinyPortal © 2005-2012