Eyepieces and Magnification for Coronado PST

[Adz]

Hey all,

A PST is going to be my next purchase, but I would like an opinion of what eyepieces are best for the scope, and preferable magnifications. I understand the PST has a sweet spot and so high quality eyepieces matter less, but hopefully my current EPs will suffice.

For my dob of 1200mm focal length:

24mm - 50x

13mm - 92x

8mm - 150x

6mm - 200x

I consider this a really good range, but what about with a 400mm focal length of the PST?

24mm - 16x

13mm - 30x

8mm - 50x

6mm - 66x

I am going to go out on a wild guess and say the highest and lower powers will be pointless...?

Cheers

[Merlin66]

It's not the sweet spot issue as much as you're only viewing in monochromatic light - there's only one wavelength Ha....

I use the Pentax zoom 24-8 regularly and the 10.4 plossl. I think your range of current eyepieces will more than cover all the bases.

[Adz]

Holey moley I just looked up your eyepiece, you lucky thing! Thanks for the reply. Have you ever used or had a PST? What is the maximum usable magnification?

[John]

... Have you ever used or had a PST? What is the maximum usable magnification?

From my brief experiences with a PST I'd say around 60x - it's a 40mm aperture scope. Personally I used a Hyperion 8mm - 24mm zoom with mine and it worked excellently. It does not work like a conventional scope though so parallels are misleading. The amount of detail you see depends on how you tune the etalon filter for example.

Ken (Merlin66) seems to know more about PST's than most

PS: You don't need premium eyepieces to get good views with a PST - I found a cheap 16mm plossl produced very pleasing views - that cost £12 off e.bay !.

[johninderby]

I found about 9mm to 12mm seemed to give the best results. The Baader orthos are particularly good. I use a Pentax zoom but the Lunt or Baader Hyperion zoom are also good. The eyepieces that you already have will be fine to start with. No need to rush out and buy other eyepiece right away when you do get a PST.

John

[Adz]

Thanks guys I thought as much. Has anyone had any luck with imaging through a PST a focally? Or is it all done prime with a webcam or CCD camera? I presume SLRs dont work?

[Merlin66]

I've used a few PST's over the years ;-)

The max mag would be with a 7-8mm eyepiece.

You can get DSLR's to focus but you need to add a barlow to get the necessary back focus.

It's much easier with a webcam (or DMK equivalent)

Check out Jan Timmermans webpage - full of detail on the PST.

[johninderby]

I dug out my old Scoptronix Maxview 40 projection eyepiece and it does work with the PST for afocal using an Olympus camera. I'll try it with the Canon 1000D and see if that works as well.

BTW Ken the parts for the PST 102mm mod should all be here about the end of the month. :D

John

[Adz]

Thanks for the advice, what would be a good barlow and power you would recommend? My two camera are in my signature.

[Merlin66]

The webcam should be OK without a barlow.

PST-EOS-Barlow-Lens

gives some ideas for the DSLR

[Mark at Beaufort]

I use my Hyperion zoom on the PST and I find that the 16mm setting is my personal favourite view. Although I sometimes use an Antares 25mm Plossl - not expensive but a good view.

Mark

[andre2]

Hi, l love do do Some “ close up” prommences fews with the pst! Its verry cool to zoom ( €50 zoom) in as close to the proms then you can also see better detail of the proms But, the last times i notice when i zoom in between 9mm up to 7.2mm the proms get pritty blurry.( also in fairly good seeings). Is there a single eyepiece witch can improve the fews , especially for close up prommences  fews for the PST. ( or most i somehow deal with it or go for a bigger apenture? Witch also can be strange becource the PST in theorie can use up to 80X usefull magnification, especially for the proms:::::? ). Thanks for your tip! ( i know that for surfice detail up to 12 or 11mm is good enough for me)

[Ceramus]

I use a Seben 24-8mm zoom. Ample range and can move quickly to higher mags in moments of better seeing.

[Merlin66]

Andre2,

The seeing and effective etalon tuning will limit the magnification.

[andre2]

Hi, “ merlin66 “ i will keep on use the pst for what iT is, but i when i have the money for the SM 60 2 or lunt tilt tune 60. Do you think that its worth to upgrade ? Or do you have another tip? Thanks!! 

[Merlin66]

The upgrade to a 60mm is very noticeable.

I use an original SM60 with the full size external etalon mounted on an ED80 and BF15 blocker.

The new SM60 II and the Lunt60 both have small internal etalons like the PST which I think compromise performance.

[andre2]

hi , i realize now that iT would be not really nesseserry to upgrade if do only visual. Onless you want use a binoviewer and imaging. I think i also find the right 2 new eyepieces now for the PST: 11mm TV plossl and a  20 mm vixen NPL .becource my zoom got broken and the eyepieces open a new world: they are more fun and relax to look through and the fews are never too dimm. The only real advange of the zoom was to zoom closer in at the prommences .....but it get broken.