I've been gazing at the sun via the PST a lot lately, and am interested in having a go at imaging through it.
How long can you capture the Sun for before the changes become too great for stacking?
I normally try to get around 1000 frames for stacking....
With my double stacked SM60 and x2.5 Powermate I need exposures of around 1/120s for the surface features...so this gives about 10sec in total; for the proms I need down to 1/11 sec exposure and this can cause problems with fast moving edges of the proms.
General answer.... a few seconds....
IMHO - no, not worth the effort!
I machined up a special adaptor to hold the two PST etalons and got it working...BUT trying to get a repeatable positioning of the etalons/ sweet spot was so sensitive - it was a real PITA!
I gave up....tooooo much effort for little return.
Having said that, there is a guy in Hong Kong who had more patience than me and did get it to work pretty well.
HTH