Binoviewer+PST

[pluton]

Hello,
Is it worth observing the sun with the PST + binoviewer?
I have a PST and a Binoviewer, but it does not focus, I have understood that in order to focus I have to acquire an OCA, whose price is about 130 dollars + shipping, I would like to know your opinion or if someone has been able to observe in this way. ..

Thanks

paul

[Highburymark]

20 hours ago, pluton said:

Hello,
Is it worth observing the sun with the PST + binoviewer?
I have a PST and a Binoviewer, but it does not focus, I have understood that in order to focus I have to acquire an OCA, whose price is about 130 dollars + shipping, I would like to know your opinion or if someone has been able to observe in this way. ..

Thanks

paul

Paul - I've never owned a PST, but I did have a Lunt LS50 for a while. You could use a binoviewer with the LS50, but you really needed a decent size blocking filter/diagonal - BF600 at least in Lunt's case, a better focuser than the stock one, and a barlow to compensate for the extra light path of the binoviewer. I'm sure it would be possible to binoview with the PST, but you'll need to experiment with these elements: blocking filter, focuser/strong mount to support the weight, and light path/barlow to reach focus.

[Stu]

You don’t need to spend that much. Unscrew the element off a Skywatcher barlow and use that, should do the job just to try it out.

[pluton]

Thank you for all reply.

Stu, you think that an element off a barlow is OK for the PST ?

Regards,

Paul

[Peter Drew]

Tried a Barlow element screwed to the front of a binoviewer fitted to a PST yesterday following the OP. It did not come to a focus. 

[Merlin]

A 3X Barlow worked for one PST observer using a W.O. binoviewer with the supplied 20mm eyepieces.

[Peter Drew]

A 3x Barlow has more chance of working but the amplification will be huge. 

[pluton]

How many magnification with the 3X Barlow + 20mm eyepiece ? 60X maybe  ?

Thanks

[Merlin]

That's about right. The optimum mag. on a PST for some observers. It still gives an whole-disc view.

[Stu]

3 hours ago, pluton said:

How many magnification with the 3X Barlow + 20mm eyepiece ? 60X maybe  ?

Thanks

Will be more than that. Placing the barlow in front of the Binoviewer dramatically increases the distance between it and the eyepiece so the amplification will be more than x3, not sure how much by but quite a lot I think.

[Peter Drew]

A 2x Barlow seems to give about 4x amplification when used with a binoviewer so a 3x is going to be far too much.  

[Merlin]

Correction folks. It was a MEADE telecentric, not a Barlow, that was used with the W.O. binoviewer.

[Rusted]

T-S offer a 2.6x GPC [glass path corrector] which they claim neutralizes the focus shortening effect of the average binoviewer.

I have one on order and can report back on its benefits when it arrives this coming week. About €39 + P&P.

Their 1.6x GPC still leaves a lot of in-focus binoviewer problems so is very unlikely to work with the PST.

T-S also offer a complete binoviewer with claimed zero power and zero GPL.

It's twice the price of their base binoviewer and has rather small clear apertures.

I believe Siebert Optics [US] also offer zero power binoviewers though at premium prices.

[pluton]

Thanks for the information, I'm going to look at the GPC 2.6X for the PST ..