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Author Topic: More pst questions  (Read 2502 times)

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Offline cugsy

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More pst questions
« on: 18:51:40, 02 June, 2013 »
Back at the spring Kelling star party the wind got under the tent (from the outside ...please) and managed to almost destroy our awning/extension with the scopes underneath. One of which was the PST. Since then I've noticed the focus was getting poor and there was a judder when I moved the focuser. And it seemed to have lost something when I tunes it.
Well, I tried many times to get the whole assembly apart and do the mod. Today I broke my second Boa - but I got the front element off followed by the tube ...attached to the etalon. Not on its own the way I wanted it.Anyway, I bunged (for want of a better word) the tube and black box assembly up the 70mm f10 ota I had as a donor scope. Eventually I managed to see something but it was very badly focussed. I assume that there is a need to make sure all of the components are parallel so that the beam will pass down the tube..Well, I cut about 100mm off the ota and got the pst further up and it was a bit better. But I just couldn't get that magic focus.
 I did manage to get the gold tube free of the black box and get the BF free of the extension. I'm wondering if I should just get the hacksaw and start a slicing? All the components but no MOD?
 Oh, I opened up the black box and straightened the prism and screw focuser and its better.   John
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline Nomis Elfactem

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Re: More pst questions
« Reply #1 on: 21:21:31, 02 June, 2013 »
John - the key is that you have to have the front of the etalon at exactly 200mm inside the focal length !!

The etalon has a 200mm focal length collimating lens to push the light though parallel then the black box at the back as an effective focal length of 200mm.

So, for my scope that is 900mm I had to do a bit of hacking too to get it to the right place (i.e. circa 700mm from the lens.  Having done a bit of testing there is a bit of play in it but you need to be 200mm or there abouts !!!  If you don't get that bit right it won't work !!

HTH's
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 cugsy

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Re: More pst questions
« Reply #2 on: 23:22:08, 02 June, 2013 »
Yep - aware of that Si. I chopped 200mm of the 70mm f10. Its the fact that I'm shoving the whole tube inside that feels wrong. Time to start cutting..
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline Nomis Elfactem

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Re: More pst questions
« Reply #3 on: 15:29:10, 03 June, 2013 »
Its the fact that I'm shoving the whole tube inside that feels wrong. Time to start cutting..

Run that bit by me again John (a photo would speak a'000 words !)... you need to get rid of the golden tube and replace it with a SCT-2" adapter or you can get specific ones from Telescope Service that fit the thread on the etalon where the gold tube went !

S.

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 swashy

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Re: More pst questions
« Reply #4 on: 19:33:04, 03 June, 2013 »
Which ERF did you plump for in the end John?
Ade

Imagine...  above us only sky!

Offline cugsy

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Re: More pst questions
« Reply #5 on: 22:32:21, 03 June, 2013 »
Reet lads - listen up.  I can get the front og off the tube and get the tube off the black box - but the tuner/etalon still attached to the bloody gold tube. I can't get it off and have 2 broken Boa straps to prove it. I ended up pushing the gold tube and black box into the 70mm donor scope.
  I haven't gotten a proper ERF yet. I tried the gold tube assembly/70mm without. Opinion says that its quite safe and I don't look like a cyclops so thats OK. I did check with a thermometer and there was absolutely no temp increase. I do have a 77mm H alpha filter from the 80's/90's that is for deepsky Ken (Merlin 66) says it will work - not brilliant but until I get a proper ERF. Then I have a 4" f11 ready for the mod....if I get to grips with this bleeding gold tube. Sic
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline Nomis Elfactem

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Re: More pst questions
« Reply #6 on: 22:41:29, 03 June, 2013 »
Arrrh... to be honest John the two I've done (with Ades help for the second one) I used a bloody big spanner to get the gold tube off and didn't worry about marking the tube (but wrap it in duck tape anyway).  Another thing to try is to put a hair dryer on it for a  few minutes (being careful not to over heat it) as that might soften the Loctite enough to shift it !

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 cugsy

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Re: More pst questions
« Reply #7 on: 22:57:09, 03 June, 2013 »
Simon - the hair drier got the front element off but wouldn't loosen the gold tube from the tuner/etalon ...at all! In the vice with tape on it and a big pair of grips just sliced into the tube. Someone has done the mod with the gold tube inserted into the donor scope. I'll have another play tomorrow.  oh well
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline swashy

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Re: More pst questions
« Reply #8 on: 08:28:49, 04 June, 2013 »
When I helped Si we wrapped the tube with rubber tape, the sort you can buy for doing a temporary water leak seal, then used pipe grips, if you have an old bike innertube that may work the same, as it just needs to grip the tube
Ade

Imagine...  above us only sky!

Offline Nomis Elfactem

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Re: More pst questions
« Reply #9 on: 09:35:04, 04 June, 2013 »
John - if you are putting the whole gold tube in with the lens still attached at he front then you aren't achieving anything by sticking it in a bigger scope... it is still being stopped down to 40mm !

One thing you could do if ALL else fails is cut the gold tube off 2" from the etalon and use it as the adapter that goes into the focuser of the donor OTA !  That does of course mean you will never get you basic PST back but once you get it modded you'll never want to go back again anyway  :laugh: :no:

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 cugsy

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Re: More pst questions
« Reply #10 on: 09:45:39, 04 June, 2013 »
No - Mr Metcalfe...No. Bad boy ..the gold tube WITHOUT the front element... :yes:  When I put the box in the bench vice and turn the tube the whole bench moves. And its about 80kg of oil stained oak that bench.  So there  :butt:
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline swashy

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Re: More pst questions
« Reply #11 on: 10:35:18, 04 June, 2013 »
You need a bigger bench !
Ade

Imagine...  above us only sky!

Offline cugsy

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Re: More pst questions
« Reply #12 on: 12:26:24, 04 June, 2013 »
Shome shuccshess....I'm dizzy with power. I chopped enough off the 70mm donor and with a lot of tape and 2" pvc pipe fitted the gold tube (minus front OG) and got some success. A focus and some better resolution. BUT - it is a crap scope and I expect better when I do the other scope.   Hopefully....and Ade I've been after another bench for ages.
Woe unto him ..or her..who tries to guide the LX90. Let him..or her..rejoice in a lightweight scope upon the mighty EQ6. Mind you,I'd sooner be looking through my 6"f8 while the clouds look down the 8"f4 Le marchant configuration. And there should be a constellation called 'Camelot' and I would worship it in the anticipation of a big lottery win. Maybe I'll move to the Isle of Man..damn these drug

Offline Nomis Elfactem

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Re: More pst questions
« Reply #13 on: 12:55:28, 04 June, 2013 »
John - how long is the remaining gold tube ??  I'd expect a far amount of vignetting unless it's (cut down) only around 2" !?!?!?

Yeap, time to get yaself a new bench John... that sounds like it's been welded in... huum, no there's a thought  :laugh: :hurt: !!

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 DrGMc

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Re: More pst questions
« Reply #14 on: 23:16:14, 30 July, 2013 »
may be a bit late for you all but did you know loctite is soluble in acetone?  So what I hear you cry - well if you don't know a friendly scientist get down to the pharmacy and look at the nail polish remover, get the high strength version and as long as you don't slosh it everywhere you should certainly loosen any wielded tubes

I'll get back in my box now ...
Meade 12", Milburn, Van slyke slider / glider, trutek SS, SXV-H9, Guide, Nags, obs & pier = skint but happy!  double stacked Ha PST, Megrez 80 II and ETX70 = even happier even skinter ... Struggling with dome automation

 

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