PST Etalon for double stacking Lunt 60

[Martin_S]

Hi , I recently flipped my LS50 front mounted etalon due to banding issues. So I'm back to single stacking .

Would it be feasible to use a PST etalon behind the internal Lunt etalon for double stacking?.

I can machine any adaptors that are needed.

Thanks in advance.

Martin

[MalVeauX]

Hi,

Yes, but it will have a very small sweet spot and require some additional optics for amplification. To make it work with the collimator lens in the PST chamber, you'd have to re-work the position behind the Lunt focuser, this may be challenging to reach focus. You will probably have an easier time by removing the collimator lens and isntead put about a 4x telecentric there (inserting into the Lunt's focuser) and follow it with the PST etalon without its collimating lens so its sitting in a F28+ telecentric light cone so it will perform correctly and it should reach focus without much effort. The increase in isolation will reduce the jacquinot spot so your sweet spot will be significantly smaller, but it will work.

Very best,

[Martin_S]

Thank you Marty, I think I'll do a PST mod instead for High Res work, the cost of a 4x telecentric is quite high in Australia.

Martin

[marktownley]

Yes, but it will have a very small sweet spot and require some additional optics for amplification. To make it work with the collimator lens in the PST chamber, you'd have to re-work the position behind the Lunt focuser, this may be challenging to reach focus. You will probably have an easier time by removing the collimator lens and isntead put about a 4x telecentric there (inserting into the Lunt's focuser) and follow it with the PST etalon without its collimating lens so its sitting in a F28+ telecentric light cone so it will perform correctly and it should reach focus without much effort. The increase in isolation will reduce the jacquinot spot so your sweet spot will be significantly smaller, but it will work.

Neat idea Marty! I like it.

[marktownley]

Thank you Marty, I think I'll do a PST mod instead for High Res work, the cost of a 4x telecentric is quite high in Australia.

Given you've already got a 4" f10 scope it makes more sense for you to use this for the PST mod. It's a very proven result.

[Martin_S]

Thanks Mark, my 4" f10 scope performs great on Cak and WL It would be great to do H-alpha as well with minimal setup times.