Bino Viewers & A PST??

[Greg]

I'm curious..

Has anyone tried or has got this configuration???

Does it reach focus?? Or does it even work..

Greg

[Merlin66]

It will work, but only if you add something like a x2 barlow up front to push the focus outside the black box.

The prime focus of the PST is usually only 4-6mm above the top edge of the eyepiece holder......

[michael.h.f.wilkinson]

I have heard of people using two Lunt LS35s in binocular configuration. Costly approach, but it could be done wit a PST I suppose.

[Helen]

I've just tried with a PST and the WO binoviewers and I can't focus with or without the supplied barlow. (My eyes also seem to struggle to merge the two sides but that's a different issue!)

Helen

[Greg]

Thanks Helen, How do you get on with the bino viewers under normal observing conditions??

Greg

[Mark at Beaufort]

Hello Greg

Same result as Helen I afraid. I have AE binoviewers with a 1.6x barlow - I tried the other day to get focus with the PST but failed. However, binoviewers are one of the best things that I bought recently. The view of the Sun in white light and the Moon through my 4" APO frac is unbelievable. I have 25mm Antares EPs and Skywatcher 15mm wide field EPs, so cheap EPs, but they are great in the binoviewers. Even the views through my 6" and 10" Newts are jaw dropping. I normally use Nagler and Ethos EPs but with the binoviewers I appear to get sharp stars across the FOV even in my f4.7 Dob. Don't understand why perhaps its the prism or the barlow, maybe both?

Mark

[Greg]

Thanks Mark.....

I think that settles it..... I've got the wallet twitch again..

[cantab]

I normally use Nagler and Ethos EPs but with the binoviewers I appear to get sharp stars across the FOV even in my f4.7 Dob. Don't understand why perhaps its the prism or the barlow, maybe both?

From what I've read the Barlow should be regarded as doubling the effective focal length of the scope, and thus the f/ratio. If correct, then it's no surprise that the Barlow improves the performance of an eyepiece in a fast scope by changing it into an effective slow scope. Of course the Barlow itself has to be good to handle the scope's fast f/ratio.

I might be barking up the wrong tree here of course though.

[BinocularSky]

If correct, then it's no surprise that the Barlow improves the performance of an eyepiece in a fast scope by changing it into an effective slow scope. Of course the Barlow itself has to be good to handle the scope's fast f/ratio.

I might be barking up the wrong tree here of course though.

No, it is exactly correct. See my Barlow tutorial at http://astunit.com/astunit_tutorial.php?topic=barlow

[Peter Drew]

You can't get a Barlow lens far enough inside the focus of a PST to bring the new focal plane through the binoviewer to the eyepiece. I made a Ha binoscope with two PST's side by side, it was fantastic, the objectives eventually went "rusty" and the PST bodies are now part of a couple of PST mods.