Blocking filter for binoviewers on PST mod

[stevil]

Hi,

I currently have a stage 1 PST mod (90mm Evostar) and am just about to embark on the stage 2 adventure.

I was thinking if perhaps using the mod with binoviewers so I was wondering if I should go for a BF10 or BF15. Is there any difference (apart from the size of the filter and the price? ) What would you recommend?

I have also started imaging with a Chameleon so my mod would be used for both observing and imaging.

Thanks

Steve

[Merlin66]

I'd go for at least the BF15.

The binoviewers will need some backfocus spacing behind the BF. Remember the distance from the PST etalon to the final focus is fixed at 200mm.

You'll need to carefully work out the spacings.....