PST question

[baggywrinkle]

This might seem a silly question but what is the orientation of the image in a PST, same as a standard refractor? inverted?

Getting to grips with the beasty now and I have found an older Excel 9mm and an 8mm Plossle I had in a Celestron EP kit seem to give the best results for visual.

I have the L bracket now and I am using it on my Vixen Porta II mount. This keeps the viewing point in a comfortable position all the time.

Once I have the Orion variable adapter I will use my smaller micro 4/3rds camera to get images.

[michael.h.f.wilkinson]

I think it has a kind of pentaprism in the housing, so the image should be correct and upright (like in a RACI finder. The LS35 has an upright but mirrored image, as do most H-alpha scopes with a diagonal type blocking filter.

[paulastro]

Mmm, that's worrying I though my long-owned PST gave an inverted image like in a reflector.  I'll check next time I use it, thanks Michael.  If I had used it to observe the recent eclipse then I would have remembered the oreintation!

[michael.h.f.wilkinson]

Mmm, that's worrying I though my long-owned PST gave an inverted image like in a reflector.  I'll check next time I use it, thanks Michael.  If I had used it to observe the recent eclipse then I would have remembered the oreintation!

Maybe there were different types during its fairly long history? 

[keithatrochdale]

Basic design has not, to my knowledge, changed.

.

[Peter Drew]

The main characteristic of a pentaprism is that although it provides deviation of the light path it doesn't alter its orientation so the image in a PST remains astronomical, left to right reversed and upside down. Other Ha telescopes use normal diagonals so produce an erect image with left and right reversed. HTH.  

[AllanJ]

I haven't tried this yet, as it has only  just occurred to me and it is cloudy, but have a look at the solar image in Spaceweather.com (which I assume is the "right" way up) and compare the location of the sunspots there and in your scope.

http://spaceweather.com/

Allan

[David Smith]

There is quite a good resource here for this and the piece of software is well worth downloading. I use it to prepare the orientation graphic in my white light images but also to figure out which way everything should be when I get confused! The site and software help file describes the PST as inverting the image. Here's how the Sun would have been orientated in a PST at 15:00 today if the PST were mounted on an alt-az mount.

HTH

David

[paulastro]

Thanks for posting that David.  it will be really useful if I can get it to work!  (not doubting the software, only my ability to use it!)

[michael.h.f.wilkinson]

Very useful tool indeed