another PST stage 2 mod

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pedro
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Re: another PST stage 2 mod

Post by pedro »

A few more images

Two different PST etalons + Coronados BF15 & BF10 ----> back distance from the etalon - 14/15cm

Imagepst_stage2_mod_20180908-013 by Pedro Ré, on Flickr

Imagepst_stage2_mod_20180908-009 by Pedro Ré, on Flickr

Imagepst_stage2_mod_20180908-005 by Pedro Ré, on Flickr

Imagepst_stage2_mod_20180908-002 by Pedro Ré, on Flickr


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Re: another PST stage 2 mod

Post by bart1805 »

And now it is a small step to doublestack the etalons. (-;


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Re: another PST stage 2 mod

Post by pedro »

Hi Bart

I have a BIG soft spot with both etalons. Very different from my other H-alpha systems


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Re: another PST stage 2 mod

Post by pedro »

PST Mod (PDF file)

http://astrosurf.com/re/PST_Stage_2_Mod ... 180911.pdf
Ré, P. (2018). PST Stage 2 Modification. Pdf file (2000kB)

more articles at:
http://re.apaaweb.com/pdfs_articles.html


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Re: another PST stage 2 mod

Post by Starry Jack »

Pedro,
In your excellent document (http://astrosurf.com/re/PST_Stage_2_Mod ... 180911.pdf), you mention the focus must come to a point 244mm from the rear of the rubber on the etalon. Where is that on your scope? The top of the diagonal? The middle of the eyepiece?


I've cobbled together a prototype yesterday using some pretty strange spare parts but it should work.

The other question is...I am using parts of a standard 2x barlow rather than the Glasspath. I've figured out the mounting in the prototype but does it need to be telecentric?

Thanks,
Jack


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Re: another PST stage 2 mod

Post by pedro »

The measurement was made by Ken Harisson:

Ken Harrison (2005). Modifying a Coronado PST Hα Solar Telescope (PDF file).

The PST etalon must be correctly placed. Final focus should be 225 mm behind the rubber ring of the etalon.

You can use other parts, a X2 barlow should work fine. It needs to be telecentric


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Re: another PST stage 2 mod

Post by Starry Jack »

Thanks, Pedro. I think my only confusion is where "final focus" is. I only use a video camera (no visual). Is that at the exit of the blocking filter? Or is it measured at the sensor chip? Or somewhere in between?

Best,
Jack


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Re: another PST stage 2 mod

Post by pedro »

Hi Jack

I tried several configurations and found out that a distance of 14cm from the rear of the PST etalon to the Coronado BF, works fine

Imagesolar_imaging_session_20180830-03 by Pedro Ré, on Flickr

ImagePST_stage_2_mod_20180830-032 by Pedro Ré, on Flickr

I did not reduce the OTA's length (did not cut the tube)

regards


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Re: another PST stage 2 mod

Post by Starry Jack »

Got it. And I also found the document you referred to so I should be good to go. The biggest difficulty seems to be finding an ok n-stock telecentric lens.

Jack


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Re: another PST stage 2 mod

Post by marktownley »

None of the lenses in this system are telecentric Jack - totally different thing!


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Re: another PST stage 2 mod

Post by OlegLviv »

I want returns to PST MOD2 because a few days ago arrived my TS 152/F5.9 and dont know how gets f10 for PST but have two ideas!

1.Buy Baader 1.7x Glasspath and will be have f10
2.I have Televue 2.0 Povermate 2x and can put front etalon but will be have F11.8

Which of the options will be the best????

Or maybe buy Lunt 50 with f7 and put Baader Glasspath 1.25?

What is the bandwidth of Pst and Lunt50? Pst 1A and Lunt 50 0,75A am right?

Thank you!


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Re: another PST stage 2 mod

Post by pupak »

AR150/F6 works well with TV5x PWMT and Quark which is similar to PST. You get F30 and the details are OK.


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Re: another PST stage 2 mod

Post by OlegLviv »

pupak wrote: Sun Nov 20, 2022 7:04 pm AR150/F6 works well with TV5x PWMT and Quark which is similar to PST. You get F30 and the details are OK.
I dont want quark because a few years sold him dont like this device.
If you know pst wants f10 without vingetting and Lunt 50 wants F7.
But now want better choice for my AR150/F6.

If you know had old model Lunt 60T with colimator f4 and its a bad choice for my AR150/F6 mod......
My friend can give me for test PST MOD2 with 2.0 Powernate2x =F11.8 or can buy Baader Glasspath 1.7 lens=F10 but PST etalon has only 1A and think that Lunt 50 with Baader Glasspath 1.7=F7.2 will be better with 0.75A than PST MOD2.

Which of the options will be the best with my TS 152/F5.9 ? (contrast and sweet spot)


https://www.facebook.com/oleg.lavigne/
https://www.astrobin.com/users/RamonLviv/
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Telescope: TS 152/900/Bresser 102/1350
Baader D-ERF 160MM
2xBaader 1.25 GPC
2xLunt 50mm
Lunt Cak B1200
Coronado BF15
Camera: Apollo Max 432M/ Apollo Mini 429M/Player One Mars II 462M/QHY 290MM
Mounh: 2xSky Watcher AZEQ6
Telecentric Lense: Televue Powermate 2/2.5x/4X/5X
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