PST double stack filter

[astroboy]

UP for sale a Coronado 40mm filter to double stack a PST to give about 5nm bandwidth so much more surface detail.
Has a tuner as well so maybe able to be teamed up with a blocking filter to make a solar scope , I'm sure others will know more about this .
Comes with case and caps.
Sells in the US for $795 plus post or the UK for 695 Quid :eyepop:
This one for $550 posted in Oz

PM if interested
Thanks
Zane

[OICURMT]

How old is it and by tuner, you mean the RichView tuner?

[/URL][URL]http://www.optcorp.com/product.aspx?pid=308-2980 (http://www.buytelescopes.com/Products/16733-coronado-instruments-solarmax-ii-40mm-double-stacking-etalon.aspx)

[Max Vondel]

Hi Astro
Do you know if this can be fitted to a coronado solarmax 40 rather than the PST?

Thanks
Peter
:)

[OICURMT]

Should be possible

Mikeyb will be able to definitively answer this, as I purchased his PST and he used to double stack it with what I think was an etalon from an SM40.

OIC!

[Max Vondel]

Thanks I'll check it out
I'm definitely interested

[MikeyB]

Factory matching is the recommended procedure for double-stacking a Solarmax 40, as with a random SM40 filter (etalon) such as this, it may not be possible to eliminate internal reflections within the range of tuning available. These reflections cause a 'second sun' effect that hampers viewing.

The advertised filter would need to be tested with the particular Solarmax 40 to determine whether or not they can be satisfactorily used in conjunction with one another.

The problem does not arise when adding a Solarmax 40 external etalon to a PST, because the PST's internal etalon is not a tilt-tuned system like the external etalon.

Also, I understand that the objective thread sizes of PST's were changed during Meade's transition to Mexican manufacture (from memory, around 2-3 years ago). The advertised filter appears to be marked "Made in USA", in which case it may not fit a Mexican-made PST. As far as I am aware, Solarmax 40's were all of US manufacture, so their thread sizing should be compatible with this filter.

[Merlin66]

The SM40 filter shown is the old style pre Rich view tuning.
The attachment thread is a 77mm 0.75pitch same as a camera filter.
I've used these for double stacking on various Ha scopes with no major issues.

[gbeal]

And if it's a 77mm thread, theres a good chance it will fit the front of the SM60 as well. My SM60 etalon has a 77mm front cap, via threads.
Gary

[Merlin66]

Thanks for that Gary....
Whoops I think that was an error.. the SM40 is definately smaller than the SM60.
I'll need to double check the thread size.

[MikeyB]

I found the Coronado instructions for an SM40 in my files - see attached.

The final section about Double Stacking refers to the need for an AP185 adaptor plate to utilise a second SM40 etalon, so perhaps screwing a second etalon onto a Solarmax 40 isn't as simple as fitting one to a PST.