60mm Solarmax II double stack question

[moriniboy]

Hi can anyone confirm if the front red element is an ERF or just a piece of red glass.

It says that it can't be use on its own so I'm assuming red glass.

Thanks Nigel

[Peter Drew]

I would think that it must be an ERF, there is no other need that I could think of. I would presume that Coronado mean that on its own it would not perform as a Ha filter and that an etalon and blocking filter would be required in addition. 

[hunterknox]

Weirdly my older Solarmax has a red front-end etalon and a red objective, so it might be that the etalons have ERFs up front but that they're not suitable for use without additional energy rejection components.

[michael.h.f.wilkinson]

That should be an ERF. The main warning is against using it without blocking filter, I think

[Merlin66]

The double stack assembly contains an upfront ERF and a tilting etalon. This could be used on its own with a standard refractor (ED80) with a BF10 blocking filter.

Interesting...my original SM60 scope had a plain objective (no ERF coating etc) but had the 60mm ERF/etalon/T max tilt mounted up front.

I've used the SM60 double stack (two up front etalons) for many years.

[moriniboy]

I'm thinking of grafting it onto the front of a 60/80mm refractor and using my spare PST black box with its ERF / BF6, any obvious flaws with this?

As I'm not using the PST etalon I assume I'm free to pick any focal length?

[Merlin66]

The PST black box IMHO is not a good option. Better to remove the eyepiece section (with the BF5) and re-mount it in a diagonal etc.

This will work.

The BF5 will cause some vignetting with focal lengths over 500mm or so.

[moriniboy]

Looking at this page it suggests that as long as I use it with my BF10 diagonal it should be ok.

Just need to decide the best 60/80mm refractor to use, any suggestions?

http://www.meade.com/products/coronado.html?cat=22

[Peter Drew]

I'm running a 60mm one with a BF15 on a SW F5 80mm refractor, very pleased with the results.